Key Concepts in Chemistry 9781774691489

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Key Concepts in Chemistry

Key Concepts in Chemistry

Rainer Roldan Fiscal

www.arclerpress.com

Key Concepts in Chemistry Rainer Roldan Fiscal

Arcler Press 224 Shoreacres Road Burlington, ON L7L 2H2 Canada www.arclerpress.com Email: [email protected]

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ABOUT THE AUTHOR

Rainer Roldan Fiscal is an Associate Professor I at the Laguna State Polytechnic University, Philippines. He finished Bachelor of Secondary Education major in General Science, Master of Arts in Teaching Science and Technology and Doctor of Philosophy in Education major in Educational Leadership and Management. He teaches Biological and Physical Science courses and Advanced Methods of Research both in the undergraduate and graduate teacher education programs. He presented his papers in national and international conferences in the Philippines and abroad like Malaysia, Thailand, and Vietnam. He published research articles in several international journals and some of them have citations.

TABLE OF CONTENTS

List of Figures ........................................................................................................ix List of Abbreviations ...........................................................................................xiii Preface...............................................................................................................xvii A ............................................................................................................... 1 B.............................................................................................................. 25 C ............................................................................................................. 36 D ............................................................................................................. 74 E .............................................................................................................. 88 F ............................................................................................................ 102 G ........................................................................................................... 113 H ........................................................................................................... 122 I............................................................................................................. 136 J............................................................................................................. 144 K............................................................................................................ 145 L ............................................................................................................ 148 M........................................................................................................... 158 N ........................................................................................................... 171 O ........................................................................................................... 180 P ............................................................................................................ 188 Q ........................................................................................................... 212 R............................................................................................................ 214 S ............................................................................................................ 225

T ............................................................................................................ 244 U ........................................................................................................... 252 V ........................................................................................................... 255 W .......................................................................................................... 261 X............................................................................................................ 264 Y............................................................................................................ 266 Z............................................................................................................ 267 Bibliography .......................................................................................... 269 Index ..................................................................................................... 275

viii

LIST OF FIGURES Figure 1. Chemical structure of abscisic acid Figure 2. Image showing chirality Figure 3. Actinomycin Figure 4. Acyl halide Figure 5. Summary of aerobic respiration Figure 6. General Aldol reaction Figure 7. Amino acid Figure 8. Autoclave is used for sterilization Figure 9. Ball Mill Figure 10. Benzene ring Figure 11. Bomb calorimeter Figure 12. Bunsen burner Figure 13. Diagram of bomb calorimeter Figure 14. Carbon atom Figure 15. Representation of carbon cycle Figure 16. Carboxylic acid Figure 17. Cell representation Figure 18. Examples of chemical bonds Figure 19. Chiral phosphoric acid Figure 20. An image representing chitin Figure 21. Chloramine (NH2Cl) Figure 22. Choline-cation-3D-balls Figure 23. Chromatography tank Figure 24. Clathrate compound Figure 25. Coal tar Figure 26. An image representing Coenzyme A (CoA) Figure 27. Collimator Figure 28. Conducting polymer

Figure 29. Conjugated protein Figure 30. Covalent bond Figure 31. Crystallization process Figure 32. An image showing cylinder of CS gas Figure 33. Cyclohexane (C6H12) Figure 34. Cytokinin Biosynthesis Figure 35. DDT (dichlorodiphenyltrichloroethane) Figure 36. Draught because of dehydration Figure 37. Dryer deliquescent Figure 38. Protein denaturation Figure 39. Deuterium Figure 40. Diazonium compound Figure 41. Diazotization mechanism Figure 42. Diffusion in a liquid Figure 43. Dioxins and dioxin-like compounds Figure 44. Magnetic dipole moment Figure 45. Disperse dyes Figure 46. Distillation process Figure 47. Dopamine Figure 48. Elastin bovine Figure 49. Electrochemistry Figure 50. Elevation of boiling point Figure 51. Enzyme action Figure 52. Filter pump Figure 53. Flavonoid Figure 54. Fluorocarbon Figure 55. Industry fossil fuel oil Figure 56. Freezing and boiling point Figure 57. Fructose Figure 58. Gel Figure 59. Gibberellic acid Figure 60. Glucose Figure 61. Halocarbon Figure 62. Heat of reaction x

Figure 63. Hemocyanin Figure 64. Histamine Figure 65. Hydrazone iodination Figure 66. Imine Figure 67. An image showing Kg measuring instrument Figure 68. Packaging of Lanolin cream Figure 69. Melting of ice in a glass Figure 70. Nitric acid in a container Figure 71. Osmosis Figure 72. Periodic Table Figure 73. Water pipette Figure 74. Vacuum distillation Figure 75. Water molecules Figure 76. X-ray of palm

xi

LIST OF ABBREVIATIONS

((CH)4NH)

Pyrrole

(CH3)2SO

Dimethyl Sulfoxide

ABA

Abscisic Acid

AlCl3

Aluminum Trichloride

BOD

Biochemical Oxygen Demand

CCl4

Tetrachloromethane

CF2:CF2

Tetrafluoroethene

CFCs

Chlorofluorocarbons

CH3

Hydrocarbon Group

CH3NH2

Methylamine

CH4

Methane

CO

Carbon Monoxide

CO

Carbonyl Group

CO2 CO

2– 3

Carbon Dioxide Carbonates

CS2

Carbon Disulfide

ESR

Electron Spin Resonance

FH2

Dihydrofolic Acid

FH4

Tetrahydrofolic Acid

GAG

Glycosaminoglycan

GERD

Gastro-Esophageal Reflux Disease

H2SO4

Sulfuric Acid

HBr

Hydrobromic Acid

HBr

Hydrogen Bromide

HCl

Hydrochloric Acid

HCl

Hydrogen Chloride

HCO3–

Hydrogen Carbonates

HDLs

High Density Lipoproteins

HF

Hydrofluoric Acid

HF

Hydrogen Fluoride

HSCS(OR)

Xanthic Acid

HSO– 4

Hydrogen Sulfates

ICME

International Conference on Multimedia and Expo

IR

Infrared

KOH

Potassium Hydroxide

KOH

Potassium Hydroxide

LDL

Low-Density Lipoprotein

LSD

Lysergic Acid Diethylamide

MSG

Monosodium Glutamate

N2

Nitrogen

NAD

Niacinamide Adenine Dinucleotide

NH2Cl

Chloramine

NH2OH

Hydroxylamine

NH3

Ammonia

NH

+ 4

Ammonium Ions

NMR

Nuclear Magnetic Resonance

O3

Trioxygen

OAA

Oxaloacetic Acid

OH

Hydroxyl Group

OH

–

Hydroxyl

ORD

Optical Rotary Dispersion

PBDEs

Polybrominated Diphenyl Ethers

PCB

Polychlorinated Biphenyl

PCl3

Phosphorus Trichloride

PH3

Phosphine

PM

Particulate Matter

HCN

Hydrocyanic Acid

PTFE

Polytetrafluoroethene

PVA

Polyvinyl Acetate

PVC

Polyvinyl Chloride xiv

RIS

Resonance Ionization Spectroscopy

SCP

Single-Cell Protein

SO

2– 4

Sulfates

TCDD

Tetrachlorodibenzo-P-Dioxin

UV

Ultraviolet

VLDLs

Very Low-Density Lipoproteins

xv

PREFACE

Chemistry is the scientific study of the properties and behavior of matter. It refers to that branch of science which deals with the properties, composition, and structure of elements and compounds, how they can undergo changes, and the subsequent energy that is released or absorbed during the process of change. Chemistry deals with not only the subatomic dimension but also with the atoms and their properties, in addition to the different laws regulating their combinations and the different ways in which the knowledge of these properties can be implemented in order to obtain certain objectives. During the course of the 20th century, there was substantial progress in the understanding of the phenomenal and complex chemistry of living organisms, together with a molecular elucidation of health and different diseases. On the other hand, chemistry in the light of recent years, assisted by progressively cultured devices, analyzes materials which are as small as single atoms and as immense and complex as DNA (deoxyribonucleic acid), which consists of millions of atoms. Chemistry revolves around the implementation and consumption of natural substances as well as the establishment of artificial ones. The various chemical processes that trace from the beginnings of civilization are cooking, fermentation, metallurgy, and glassmaking. Some basic aspects of chemistry are organic, inorganic, and analytical chemistry, where Organic chemistry refers to the analysis of the structure, properties, reactions, compositions, as well as the formation of carbon-containing compounds. Nearly all the organic compounds carry carbon along with hydrogen, and they might also incorporate any number of other elements such as nitrogen, oxygen, phosphorus, halogens, silicon, and sulfur. Organic chemistry is initially restricted to the analysis of compounds that are formed by living organisms; it has been expanded so as to incorporate substances that are humanmade, for example, plastics. On the other hand, inorganic chemistry refers to the compounds which carry carbon atoms in them. Therefore, the branch of chemistry that concerns with the research of compounds, which does not comprise atoms of carbon-hydrogen in it, is known as inorganic chemistry. In other words, it is antagonistic to organic chemistry. The substances which do not contain the bonding of carbon-hydrogen are metals, salts, and chemical substances.

Most of the elements are scientifically essential, such as titanium, iron, nickel, and copper, for instance, these are used systematically and electrically. While the transition metals construct numerous useful alloys, with each other as well as with other metallic elements. Talking about analytical chemistry, it refers to the branch of chemistry that deals with the analysis of various substances. The abundance of the materials that takes place on Earth, for example, wood, minerals, coals, or air are a fusion of a lot of different and distinguished chemical substances. Each and every pure chemical substance such as oxygen, water, or iron has a distinguished set of properties that provides it its chemical identity. Analytical chemistry is significant in various dimensions, such as the destruction of the environment has taken place since the time civilization was emerging, and the various issues concerning environmental pollution have expanded with the evolution of the global population. The methods of analytical chemistry are dependent on largely in order to maintain an amicable environment. Chemistry as a field of study deals with several basic concepts and aspects which are mentioned above yet to define it more extensively. It revolves around the mass number and atomic number by providing information about them on different elements. It illustrates the chemical reaction, reactants, and chemical combinations by emphasizing on their significance in everyday life. It also sheds light on the nature of matter, laws of chemical combination, atomic theory, atomic structure, as well as the different concepts and theories associated with them such as the Mole concept. This book will introduce the readers to the field of chemistry, and the various key concepts in chemistry. It is precisely designed for readers or students with no prior experience related to chemistry and its various aspects and touches upon a diversity of fundamental topics. By the end of the book, readers will understand the basic knowledge of chemistry and its various dimensions involved.

Key Concepts in Chemistry

1

A Abscisic Acid (ABA) Abscisic Acid is a type of plant hormone. It is instrumental in performing numerous functions in the developmental stages and processes of a plant, for example, the shedding (abscission) of flowers and fruit and for the beginning of dormancy in buds; thereby its early name; dormin. This compound is also related to controlling the organ size and closing of pores (stoma), i.e., stomatal closure in the leaves of plants suffering loss of water.

Figure 1. Chemical structure of abscisic acid. Source: Image by pixabay.

   It refers to the spatial configuration of atoms of a chiral molecule, as denoted by comparison with a reference molecule or by some sequence rule. The two most frequently used systems for denoting absolute configuration are: the D–L convention and the R–S convention.

Absolute Temperature      !"#$%   Celsius temperature. Absolute temperature, also referred to as thermodynamic temperature, was a fundamental measure of temperature established on & ' %       **/5#   %*/ >  /% <   ? >

   5      > =<   > #J!"#$Q    % Y!"#$ >         zero. In practice substances become solids at these temperatures; however,  ?             Y!"#$Z&

2

Key Concepts in Chemistry

     /Z 5   [ =            \   ]   >          5Z=  ^>5Z^=  _   &`    thermodynamic temperature scale commonly used today on which the unit is the Kelvin.

Absorption Absorption, in chemistry, refers to the chemical process wherein the atoms, molecules, or ions enter a bulk phase, i.e., either liquid or solid material. In simple terms, a phenomenon in which a gas is taken up by a liquid or solid, or in which a liquid is taken up by a solid. It is often found that solids that absorb gases or liquids have a porous structure. A more generic term; sorption is used in cases where the absorption of gases in solids takes place. There is a marked difference between There is a distinction between absorption (in which one substance is assimilated into the bulk of another) and adsorption, i.e., a surface phenomenon, which involves attachment to the surface. %         {  For instance, in the case of a porous solid such as activated charcoal, it may be seen that it absorbs a large quantity of gas, while the process underway could actually be adsorption; on the high surface area of internal pores in the material. The process of absorption simply means that a substance captures energy and further transforms it, for example, when electromagnetic radiation, particles, or sound waves lose energy while passing through a medium. Therefore, absorption involves the conversion or transformation of one form of energy into another.

Accelerator Accelerator, in chemistry, refers to a substance that increases the rate of a chemical reaction. This characteristic makes it similar to a catalyst. It is a common practice to cite catalysts as ‘accelerators’ in some specific industrial applications. For instance, in the process of vulcanization of rubber, accelerators are used to speed up the process with higher effectiveness as also in the polymerization of adhesives. A distinction between catalyst and accelerator can be drawn in the production of composite materials using polyester resins; wherein the

Key Concepts in Chemistry

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catalyst (which triggers the polymerization reaction) and the accelerator (which is an additional substance making the catalyst more effective). The terms promoter and activator are used in a similar way.

Acenaphthene A colorless crystalline derivative of naphthalene and used mostly in the production of certain dyes.

Acetal Acetal is a type of compound formed by the reaction of an alcohol with either an aldehyde or a ketone. The formation of an acetal happens when the hydroxyl group of a hemiacetal becomes protonated and is lost as water. The carbocation that follows is quickly attacked by a molecule of alcohol. Loss of the proton from the attached alcohol forms the acetal. The first step in the formation of an acetal is the formation of an intermediate, known as a hemiacetal. For example, ethanol (acetaldehyde; CH3CHO) reacts with ethanol (C2H$OH) as follows: CH3CHO + C2H$|}~&}5|}=5&}3) (C2H$O). The hemiacetal has a central carbon atom (from the aldehyde) attached to a hydrogen, a hydroxyl group, a hydrocarbon group (CH3), and an alkoxy group (C2H$O). If a ketone is used rather than an aldehyde, the resulting hemiacetal contains two hydrocarbon groups. Like for example, reaction of the ketone R1COR2 with the alcohol R3OH.

Acetyl CoA Acetyl-CoA (acetyl coenzyme A) is a molecule that plays an important role in numerous biochemical reactions in protein, carbohydrate and lipid metabolism. It is particularly responsible for the oxidation of sugars, fatty acids, and amino acids, and in certain biosynthetic pathways. Acetyl-CoA is formed either by oxidative decarboxylation of pyruvate from glycolysis, where glucose is broken down into two three-carbon molecules of pyruvate; which occurs in mitochondrial matrix, by oxidation of long-chain fatty acids, or by oxidative degradation of certain amino acids. The acetyl group of acetyl CoA is subsequently oxidized in the Krebs cycle, to yield reduced coenzymes and carbon dioxide. Acetyl CoA is also produced in the initial oxidation of fatty acids and some amino acids. A few other major functions of Acetyl-CoA are the provision of acetyl groups in the biosynthesis of fatty acids, terpenoids, and other substances.

4

Key Concepts in Chemistry

Achiral In chemistry, it is described as any molecule or ion that does not have chiral properties; i.e., one that does not exhibit optical activity. It refers to any molecule that is symmetric in such a manner that it can be superimposed on its mirror image.

Figure 2. Image showing chirality. Source: Image by Wikimedia.

Acid An acid is referred to as any substance that tastes sour when poured in water, transforms blue litmus paper to red, reacts with metals to release the hydrogen it contains, and reacts with basic substances to form salts. It           >   }~ H+ + A–. More accurately, the hydrogen ion is solvated (a hydronium ion): HA + H2|~}3O+ + A–. Strong acids are completely dissociated in water. Sulfuric acids, nitric acids, hydrochloric acids, phosphoric acid, and trichloroethanoic acid are some of its examples. Weak acids are only partially dissociated. It is commonly observed that most organic carboxylic acids are weak acids. In contrast to acids, bases are those chemical compounds that produce hydroxide ions in water. Bases are either ionic hydroxides (e.g., NaOH) or compounds that form hydroxide ions in water.

Acid Dyes Acid dyes are essentially sodium salts of organic acids used to dye wool, silk and nylon fabrics. They are called so since they are applied from a bath acidified with dilute sulfuric or ethanoic acid.

Key Concepts in Chemistry

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Acidic Acidic refers to having a tendency to release a proton or to accept an electron pair from a donor. In aqueous solutions, the pH is a measure of the acidity, i.e., an acidic solution is one in which the concentration of H3O+ exceeds that in pure water at the same temperature; i.e., the pH is lower than 7. A pH of 7 indicates a neutral solution.

Acidic Hydrogen Acidic hydrogen is a hydrogen atom found in an acid that forms a positive ion as the acid dissociates; it enters into dissociation equilibrium when the molecule is dissolved in a solvent. For example, in ethanoic acid (CH3COOH) the acidic hydrogen is the one on the carboxyl group, –COOH: CH3COOH + H2|~&}3COO– + H3O+.

Acid Value The acid value is the number of milligrams of potassium hydroxide (KOH) necessary to neutralize the fatty acids in 1 gram of sample. It is a measure of the free acid present in fats, oils, resins, plasticizers, and solvents.

Acridine Acridine is a colorless organic crystalline heterocyclic compound with three fused rings. Certain acridines such as proflavine have antiseptic properties, and derivatives of acridine are used as dyes and biological stains.

Acrilan Acrilan is a synthetic acrylic texture fiber made from a polymer with an average molecular weight of -100,000, about 1900 monomer units. It consists of a copolymer of 1-cyanoethene (acrylonitrile; vinyl cyanide) and ethenyl ethanoate (vinyl acetate).

Acrylic Resin A synthetic resin made by polymerizing an amide, nitrile, or ester derivative of 2-propenoic acid (acrylic acid). Acrylic resins (known as ‘acrylics’) are used in a variety of ways. A common example is poly(methyl methacrylate), which is produced by polymerizing methyl methacrylate, CH2:CH(CH3) COOCH3. This is the clear material sold as Plexiglas. Another example

6

Key Concepts in Chemistry

is the compound methyl 2-cyanoacrylate, CH2:CH(CN)COOCH3. This polymerizes very readily in air and is the active constituent of ‘superglue.’ In both these cases, there is a double C=C bond conjugated with the carbonyl C=O bond and the polymerization has a free radical mechanism. The free election is on the carbon atom next to the carbonyl group, which stabilizes the radical. Another example of an acrylic polymer is formed by free-radical polymerization of acrylonitrile (CH2:CHCN) to give poly5  =  5   =`  % the unpaired electron is on the carbon next to the –CN group. Acrylic resins are also used in paints.

Actinic Radiation Actinic radiation implies an electromagnetic radiation that can cause a chemical reaction or that impacts a photographic emulsion; for instance, ultraviolet radiation is actinic.

Actinomycin Actinomycin, also known as Dactinomycin, is a chemotherapy medication that is used to treat a number of different forms of cancer. It simply means any of a number of antibiotics produced by certain bacteria. Actinomycin D is a popular antibiotic of the actinomycin group that exhibits high antibacterial and antitumor activity.

Figure 3. Actinomycin.

Source: Image by Wikimedia.

Key Concepts in Chemistry

7

Action Spectrum A graph that indicates the effect of different wavelengths of radiation, usually light, on a certain process. It is often similar to the absorption spectrum of the substance that absorbs the radiation and therefore is helpful in the identification of that substance. For instance, the action spectrum of photosynthesis is similar to the absorption spectrum of chlorophyll.

Activation Energy It refers to the minimum amount of energy that is required by a system before a chemical reaction can occur, irrespective of whether the reaction is exothermic or endothermic. Activation energy is often considered as an energy barrier that needs to be overcome to allow a chemical reaction to occur.

Active Site Active site refers to the site on the surface of a solid catalyst at which a particular catalytic activity occurs or at which a catalyst is particularly effective. It refers to the region of an enzyme molecule that collaborates with and acts on the substrate. It consists of catalytic amino acids arranged in a configuration specific to a particular substrate or type of substrate. The ones that are in direct combination are the contact amino acids. Other amino acids may be further away but still play a role in the action of the enzyme. These are called auxiliary amino acids. When binding of a regulatory compound occurs on a separate site, it is called the allosteric site, and the enzyme molecule             [ >

Activity Some specific thermodynamic properties of a solvated substance are dependent on its concentration (e.g., its tendency to react with other substances). Real substances show departures from ideal behavior, and a corrective concentration term – the activity – has to be introduced into equations describing real solvated systems.

Acylation In chemistry, acylation, also known as alkanoylation, is referred to as the process of adding an acyl group to a compound. It involves any reaction

8

Key Concepts in Chemistry

that introduces an acyl group (RCO–) into a compound. Acylating agents are compounds such as acyl halides (RCOX) and acid anhydrides (RCOOCOR), which react with such nucleophiles as H2O, ROH, NH3, and RNH2. In these reactions, a hydrogen atom of a hydroxyl or amine group is replaced by the RCO– group. In acetylation the acetyl group (CH3CO–) is used. In benzoylation the benzoyl group (C6H$CO–) is used. Acylation is used to prepare crystalline derivatives of organic compounds to identify them (e.g., by melting point) and also to protect –OH groups in synthetic reactions.

Acyl Halide An acyl halide is a type of chemical compound derived from an oxoacid after replacing a hydroxyl group with a halide group. The general formula of this compound is RCOX, where R represents an alkyl group, while CO is the carbonyl group and X represents the halide, for example chloride. Acyl halides can be prepared by the reaction of a carboxylic acid with a halogenating agent. Commonly, phosphorus halides are used (e.g., PCl$) or a sulfur dihalide oxide (e.g., SOCl2): RCOOH + PCl$~€&|&|&3 + HCl RCOOH + SOCl2~€&|&Q|2 + HCl. The acyl halides have irritating vapors and fumes in moist air. They are very reactive to the hydrogen atom of compounds containing hydroxyl (–OH) or amine (–NH2) groups. For example, the acyl halide ethanoyl chloride (acetyl chloride; CH3COCl) reacts with water to give a carboxylic acid (ethanoic acid).

Figure 4. Acyl halide. Source: Image by Wikimedia.

Addition Reaction An addition reaction in organic chemistry refers to an organic reaction where two or more molecules combine to form a larger molecule. It is a

Key Concepts in Chemistry

9

reaction in which additional atoms or groups of atoms are introduced into an unsaturated compound, such as an alkene, alkyne, aldehyde, or ketone. A simple example is the addition of bromine across the double bond in ethene: H2C:CH2 + Br2~‚}2CCH2Br Additional reactions can occur by addition of electrophiles or nucleophiles.

Adenine Adenine is a nucleobase found in the nucleic acid of DNA and RNA. It is also a constituent of certain coenzymes, and when combined with the sugar ribose, it forms the nucleoside adenosine found in AMP, ADP, and ATP. Adenine is a purine derivative and has a purine ring structure.

Adenosine Adenosine is an organic compound that is present in all human cells. It is     { ƒ\€    „\  bond. It is found in the form of either free nucleoside or in combination in nucleic acids. Phosphate esters of adenosine, such as ATP, are important carriers of energy in biochemical reactions.

Adiabatic Change In an adiabatic change, there is no heat transfer, and no energy enters or leaves the system. An adiabatic process is a type of thermodynamic process which takes place in the absence of heat or mass transfer between the system and its surroundings. In an adiabatic expansion of a gas, mechanical work is done by the gas as its volume increases and the gas temperature falls. For an     >       *† ^#†#Y†^ *†Y#^" ^#%^% ^"    †          

Adsorption Adsorption is a mass transfer process that is a phenomenon of sorption of gases or solutes by solid or liquid surfaces. In simple terms, it is a process in which a layer of atoms or molecules of one substance forms on the surface of a solid or liquid. All solid surfaces take up layers of gas from the surrounding atmosphere). A few common examples of adsorbents are clay, silica gel, colloids, and metals.

10

Key Concepts in Chemistry

Aerobic Respiration Aerobic respiration is simply a chemical reaction that deports energy to the cells. It is the respiration in which free oxygen is used to oxidize organic substrates to carbon dioxide and water, with a high yield of energy. The waste products of aerobic respiration are carbon dioxide and water. Carbohydrates, fatty acids, and excess amino acids are broken down, yielding acetyl CoA and the reduced coenzymes NADH and FADH2. The acetyl coenzyme A enters a cyclic series of reactions, the KREBS CYCLE, with the production of carbon dioxide and further molecules of NADH and FADH2. NADH and FADH2 are passed to the electron-transport  5> >    ˆ >  =%      atoms of free oxygen to form water. Energy released at each stage of the chain is used to form ATP during a coupling process. The substrate is completely oxidized, and there is a high energy yield. There is a net production of 38 ATPs per molecule of glucose during aerobic respiration, a yield of about 19 times that of anaerobic respiration. Aerobic respiration is therefore the preferred mechanism of the majority of organisms.

Figure 5. Summary of aerobic respiration. Source: Image by Wikimedia.

Agent Orange An herbicide and defoliant chemical containing a mixture of two weed killers 5%‰\ƒ %‰%$\=`        for defoliating forest areas in Vietnam by the U.S. military to know where an enemy may be hiding or to destroy enemy crops. Agent Orange derived its name from the color-coded bands painted around the drums holding the

Key Concepts in Chemistry

11

herbicides. Exposure to the highly toxic chemical dioxin, which is present in it, is known to cause many forms of cancer and birth defects.

Alcohol In chemistry, alcohol is any of a class of organic compounds characterized      ?5Š|}=             alkyl group (hydrocarbon chain). The general formula is ROH, where R is a hydrocarbon group. The most common examples of simple alcohols are methanol (CH3OH) and ethanol (C2H$OH). Alcohols have the –OH group attached to a carbon atom that is part of an alkyl group. If the carbon atom is part of an aromatic ring, as in PHENOL, C6H$OH, the compound does not have the characteristic properties of alcohols. Phenylmethanol (C6H$CH2OH) does have the characteristic properties of alcohols (in this case, the carbon atom to which the –OH is attached is not part of the aromatic ring). Alcohols can have more than one –OH group; those containing two, three, or more such groups are described as dihydric, trihydric, and polyhydric respectively (as opposed to alcohols containing one –OH group, which are monohydric.

Aldehyde Aldehyde, any of a class of organic compounds in which a carbon atom shares a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom or group of atoms (designated R in general chemical formulas and structure diagrams). Aldehyde is a chemical compound with a functional group -CHO. The general formula of alkene is CnH2n+1 so the general formula for aldehyde will be CnH2n+1CHO or CnH2nO. Common examples of aldehydes are methanal (formaldehyde; HCHO) and ethanal (acetaldehyde; CH3- CHO). Aldehydes are made by oxidizing a primary alcohol; in the laboratory, potassium dichromate (VI) is used in sulfuric acid. The aldehyde produced can be oxidized further to a carboxylic acid        dichromate(VI) solution used as the oxidizing agent. Reduction (using a catalyst or nascent hydrogen from sodium amalgam in water) produces the parent alcohol. For example, oxidation of ethanol (C2H$OH) gives ethanal (acetaldehyde; CH3CHO).

12

Key Concepts in Chemistry

Aldol Reaction A reaction in which two molecules of aldehyde combine to give an aldol – example given is a compound containing both aldehyde and alcohol functional groups. For example, the aldol reaction has been used in the large-scale production of the commodity chemical pentaerythritol and the synthesis of the heart disease drug Lipitor (atorvastatin, calcium salt). The reaction is base-catalyzed; the reaction of ethanal (acetaldehyde) ˆ?     ?>&}3&}|~&}3CH(OH)CH2CHO.        &      is removal of a proton to give a carbanion, which subsequently attacks the carbon of the carbonyl group on the other molecule: CH3&}||}Y~Y CH2CHO + H2O CH3CHO + –CH2&}|~&}3CH(OH)CH2CHO.

Figure 6. General aldol reaction. Source: Image by Wikipedia.

Alginic Acid Alginic acid, also known as algini, is a complex polysaccharide distributed widely in the cell walls of brown algae that is hydrophilic and forms a viscous gum when hydrated. It is a yellow-white organic solid that is found in brown algae. Alginic acid has various uses, especially in the food industry as a stabilizer and texture agent and in medicine to treat symptoms of stomach ulcers, gastroesophageal reflux disease (GERD), and other conditions caused by excess stomach acid.

Aliphatic Compound Aliphatic compound is any chemical compound belonging to the organic class in which the atoms are connected by single, double, or triple bonds to form nonaromatic structures. While aliphatic compounds are the hydrocarbons that are the open-chain compounds and also closed chains, aromatic compounds are those that have only a closed chain structure.

Key Concepts in Chemistry

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Alizarin An important orange-red organic compound used in the dyestuffs industry to produce red lakes. It occurs naturally in the root of the plant and may also be synthesized from anthraquinone.

Alkali Alkali is any of the soluble hydroxides of the alkali metals—i.e., lithium, sodium, potassium, rubidium, and cesium. Alkalis are strong bases that turn litmus paper from red to blue; react with acids and produce neutral salts; and are caustic and in concentrated form are corrosive to organic tissues. Common examples of alkalis are sodium hydroxide and potassium hydroxide.

Alkaloid Alkaloid is one of the groups of natural organic compounds found in plants. They contain oxygen and nitrogen atoms; most are poisonous. However, they include a number of important drugs with characteristic physiological effects, e.g., morphine, codeine, caffeine, cocaine, and nicotine.

Alkane Alkane is a type of hydrocarbon with the general formula CnH2n+2. Alkanes are saturated compounds, containing no double or triple bonds. Systematic names end in -ane: methane (CH4) and ethane (C2H6) are typical examples. The alkanes are fairly unreactive (their former name, the paraffins, means ‘small affinity’). In ultraviolet radiation, they react with halogens to give a mixture of substitution products. This involves a free-radical chain reaction and is important as a first step in producing other compounds from alkanes.

Alkene Alkene is a type of aliphatic hydrocarbon containing one or more double bonds in the molecule. Alkenes with one double bond have the general formula CnH2n. The alkenes are unsaturated compounds. They can be obtained from crude oil by cracking alkanes. Systematic names end in -ene: examples are ethene (C2H4) and propane (C3H6), both of which are used in plastics production and as starting materials for the manufacture of many other organic chemicals. The former general name for an alkene was olefin.

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Key Concepts in Chemistry

Alkoxide Alkoxide is an organic compound containing an ion of the type RO–, where R is an alkyl group. Alkoxides are formed when a hydrogen atom is removed from a hydroxyl group of alcohol when reacted with a metal. For example, ethanol reacts with sodium to give sodium ethoxide: 2C2H$OH  Œ  ~ &2H$O–Na+ + H2. Alkoxides are ionic compounds containing an alkoxide ion (RO–). They are named according to the parent alcohol; i.e., methanol (CH3OH) gives methoxide CH3O–, ethanol (C2H$OH) gives ethoxides C2H$O–, etc.

Alkylbenzene Alkylbenzene are derivatives of benzene, in which one or more hydrogen atoms are replaced by alkyl groups of different sizes. They are a type of organic hydrocarbon containing one or more alkyl groups substituted

   [   [ 5 ] &Ž}$&}"=     example. The Friedal-Crafts reaction and the Wurtz reaction are methods of generating alkylbenzenes and use alkyl halides as reactants. In industries, huge quantities of methylbenzene are produced from crude oil. Substitution of alkylbenzenes can occur at the benzene ring; the alkyl group directs the substituent into the 2- or 4-position. Substitution of hydrogen atoms on the alkyl group can also occur.

Alkyl Group In organic chemistry, an alkyl group is referred to as a functional group of an organic chemical that contains only carbon and hydrogen atoms, which are arranged in a chain. An alkyl group is formed by removing a hydrogen atom from an alkane or other aliphatic hydrocarbon. For example, the methyl group (CH3–) is derived from methane (CH4).

Alkyne In organic chemistry, an alkyne refers to an unsaturated type of hydrocarbon containing a minimum of one or more carbon triple bonds in its molecule. The most basic alkynes with a single triple bond have the general chemical formula CnH2n–2. The alkynes are unsaturated compounds. The first and simplest member of the alkyne family is ethyne (C2H2), which has two carbon atoms bonded by a triple bond. It can be prepared by the action of

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water on calcium carbide. CaC2 + 2H2|~& 5|}=2 + C2H2. Alkynes were earlier known as acetylenes.

Allosteric Site In the field of biochemistry, allosteric site refers to the particular part of the enzyme formed by various amino acids that provide the modulation of enzymatic activity. A part of an enzyme detaches from the active site to which a specific effector or modulator can be attached. This attachment is reversible and alters the activity of the enzyme. Allosteric enzymes also possess an allosteric site along with their active site. This site is as specific in its relationship to modulators as active sites are to substrates. A few iron enzymatic proteins, for example, hemoglobin, also undergo allosteric effects.

Alpha-Naphthol Test Alpha-naphthol test is a standard biochemical test undertaken to detect the presence of carbohydrates in solution. It is also known as Molisch’s test (after the Austrian chemist H. Molisch, who devised it). The test includes a small amount of alcoholic alpha-naphthol being mixed with the test solution and concentrated sulfuric acid is added alongside. The presence of carbohydrates is indicated by the formation of a violet ring at the intersection of the two liquids.

Amalgam An amalgam is an alloy of mercury with one or more of another metal. Amalgams can be found in both liquid and solid forms. An amalgam of sodium (Na/Hg) with water is used to produce hydrogen gas.

Amination Amination is the process wherein an amino group (–NH2) is introduced into an organic molecule or compound. An example of amination is the conversion of an aldehyde or ketone into an amide by reaction with hydrogen and ammonia in the presence of a catalyst: RCHO + NH3 + H2~€&}2NH2 + H2O.

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Key Concepts in Chemistry

Amine In organic chemistry, amines are defined as compounds or functional groups that contain a nitrogen atom bound to hydrogen atoms or hydrocarbon groups. Amines have the general formula R3N, where R can be hydrogen or an alkyl or aryl group. They can be prepared by reduction of amides or nitro compounds. Amines      %   %      whether one, two, or three of the hydrogen atoms of ammonia have been replaced by organic groups. Since amines are basic, they can form the quaternary ion, R3NH+. Hofmann rearrangement, also called Hofmann degradation, is the reaction of a primary amide with a halogen (chlorine or bromine) in strongly basic (sodium or potassium hydroxide) aqueous medium, which converts the amide to a primary amine. All three types, plus a quaternium salt, can be produced by the Hoffman Degradation.

Amine Salt Amine salt is a salt similar to an ammonium salt, but with organic groups attached to the nitrogen atom. Amine salts are generally made by reacting amines with strong acids; for example, triethylamine ((C2H$)3N) will react with hydrogen chloride to give triethylammonium chloride: (C2H$)3N + HCl ~5&2H3)3NH+Cl–. Salts of this type may have four groups on the nitrogen atom, for example, with chloromethane, tetraethylammonium chloride can be formed: (C2H$)3N + C2H$& ~ 5&2H$)4N+Cl– Sometimes amine salts are named    ? ’\']    %  5&6H$NH2) forms anilinium chloride C6H$NH3 +Cl–. Insoluble alkaloids are frequently used as a main component in medicines in the form of their amine salt (sometimes referred to as the ‘hydrochloride’).

Amino Acid Amino Acid is a derivative of a carboxylic acid in which a hydrogen atom in an aliphatic acid has been replaced by an amino group. Thus, from ethanoic acid, the amino acid 2-aminoethanoic acid (glycine) is formed. The amino acids of special interest are those that occur as constituents of naturally occurring peptides and proteins. All of these have the –NH2 and –COOH groups attached to the same carbon atom; i.e., they are alpha-amino acids. All of them are white, crystalline, soluble in water (but not in alcohol), and, with the sole exception of the simplest member, all are optically active.

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Figure 7. Amino acid. Source: Image by Britannica.

In the human body too, amino acids are responsible for various relevant processes such as tissue growth and building proteins. Therefore, all amino acids are essential in adequate quantities for the human body. In an adult human body, twelve out of the twenty amino acids can be manufactured by the body itself. As these are not a prerequisite in the diet, they are referred to as non-essential amino acids. The rest of the eight amino acids cannot be synthesized by the body and, therefore, have to be ingested in the form of supplements and are known as essential amino acids.

Amino Sugar In organic chemistry, an amino sugar is referred to as a sugar molecule, in which a hydroxyl group (OH) has been replaced by an amino group (NH2). Glucosamine (from glucose) is a common example of amino sugar, found in abundance in many polysaccharides of vertebrates and is a vital component of chitin. Galactosamine or chondrosamine (from galactose) is a major component of cartilage and glycolipids. Amino sugars are a crucial element in the formation of bacterial cell walls.

Ammonia (NH3) Ammonia is a colorless gas, best recognized by its trademark strong odor formed due to the combination of nitrogen and hydrogen atoms. Ammonia has a good cooling capacity and after compression, it forms a colorless liquid, which turns into a white solid when fully cooled.

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Key Concepts in Chemistry

Ammonia gas is highly dissolvable in water (a saturated solution at /Z&    "Ž“”    =]   _      {   contains a proportion of free ammonia. Ammonia also easily dissolves in ethanol. It reacts with acids to form ammonium salts; for instance, it reacts with hydrogen chloride to form ammonium chloride: NH35=}&5=~ NH4Cl(g).

Amphoteric Amphoteric is a molecule or compound that can react as both an acid as well as a basic; and display both properties. The term is generally used for metals that form amphoteric oxides and hydroxides such as zinc, tin, lead, aluminum, and beryllium that can form both cations and complex anions. For example, zinc oxide dissolves in acids to form zinc salts and also dissolves in alkalis to form zincates [Zn(OH)4]2–.

Anabolic Steroid Anabolic steroid is a steroid hormone or synthetic steroid that encourages new tissue growth and development. Treatment of deteriorating illnesses is done using anabolic steroids. They are also utilized in agriculture to increase cattle productivity. People also take them to bulk up their muscles, but this is now largely prohibited in sports.

Anaerobic Respiration Respiration that does not require oxygen and it is observed in yeasts, bacteria, and, in rare occasions, muscle tissue. The organic substratum is not totally oxidized in this form of respiration and the energy production is poor. Glycolysis degrades glucose into pyruvate in the absence of oxygen in animal muscle tissue, generating a tiny amount of energy as well as lactic acid, which may be oxidized subsequently when oxygen becomes available. An example of anaerobic respiration is fermentation that results in certain yeasts producing ethanol and carbon dioxide. This procedure produces only two ATP molecules.

Anhydride A compound created through extraction of water from an acid or, less frequently, a base. Many nonmetal oxides are anhydrides of acids, such as CO2, which is an anhydride of H2CO3 or SO3, which is an anhydride

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of H2SO4. By eliminating H2O from two carboxylic acid groups, organic anhydrides are produced, yielding molecules having the functional group –CO.O.CO–. These are members of the acid anhydrides class of organic compounds.

Anionic Resin An ion-exchange substance that is capable of exchanging anions in the surrounding medium for anions such as Cl– and OH–. These resins are utilized for a variety of analytical and purification applications. They are frequently synthesized by reacting a stable polyphenylethene resin with a quaternary ammonium group (N(CH3)4 +) or a phenolic group (–OH–). A common exchange reaction is: resin–N(CH3)4 +Cl–^|}~YŒ5&}3)4 +OH– + KCl. Anionic resins can be used to separate halide ion combinations. Such mixes can be attached to the resin and separated by elution.

Annulene A ring compound with double and single C–C bonds that alternate. The next annulene larger than benzene is C8H8, which has an eight-membered ring of carbon atoms. Since it is not planar and does not follow the Hückel rule, it is not an aromatic compound. C8H8 is known as cyclo-octatetraene. The number of carbon atoms in the ring determines the higher annulene. The Hückel rule is satisfied by [10]-annulene, however it is not aromatic because the hydrogen atoms inside the ring interact, causing it to be nonplanar. Aromatic characteristics of [18]-annulene, a stable red solid, have been observed.

Anode Anode is the electrode in electrolysis that has a positive potential in relation to the cathode. The anode is the terminal at which electrons move out of any electrical system, such as a discharge tube or electronic device.

Anomer Is any one of the two isomeric forms of a cyclic sugar, varying in the location of the –OH group on the carbon adjacent to the ring’s O atom (the anomeric   =        %                    process possesses a changed state along with a six-membered ring. The free radical is new and more uniform as compared to the original one. Additional polymerization takes place at the electrons that are new and unpaired, which results in the construction of polymers together with butyl (CH3CH2CH2CH2–) side chains.

Bakelite A most usual thermosetting synthetic polymer fabricated through the condensation of phenol (C6H$OH) along with methanal (formaldehyde, HCOH). It is a classic instance of a phenolic resin (or phenol-formaldehyde resin) and was regarded as one of the first functional synthetic polymers which also has many uses. The reaction which occurs between phenol and methanal requires certain specific conditions like it happens under acid conditions and incorporates electrophilic substitution on the surface of a benzene ring in order to provide a framework of the three-dimensional polymeric structure. Bakelite is given such a name after Leo Hendrik Baekeland (1863–1944), a Belgian-born US chemist, who is known for discovering Bakelite in the year 1909.

Ball Mill A device generally implied in the chemical industry and is responsible for grinding solid material. Ball mills most commonly have gradual rotating steel-lined drums which hold steel balls. The material is compressed by the collapsing action of the balls which occurs in the drum. Hammermill can be juxtaposed here.

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Key Concepts in Chemistry

Figure 9. Ball mill. Source: Image by Flickr.com.

Banana Bond In strained ring mixtures, the bond angles that are supposed to be constructed by means of the hybridization of orbitals are disparate to the angles that are acquired by consolidating the atomic centers. In cases like these, it is often conjectured that the bonding orbital is either twisted or in a shape which is banana-like. For instance, in cyclopropane, the three carbon atoms are

 [ _   % Ž/Z     The sp3 [   >     ? #/‰Z  the orbitals. In consequence, the orbitals extend over each other at an angle, resulting in a banana bond. The term ‘banana bond’ is also implemented in a discrete manner for a polycentric bond of the category available in     > % ? %  5‚2H6).

Band Spectrum A spectrum that emerges as numerous bands of radiations that are discharged or absorbed and it is a band spectrum. Band spectra are attributes of

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molecules, and most of the time, each band can be set into a number of spaced lines that are closely associated to each other. The various bands correspond to transitions of electron orbit present in the molecules and the firmly spaced lines in an individual band, seen under the light of excessiveresolution, are the outcome of distinct vibrational phases of the molecule.

Barrel An assessment or estimation of volume at times implemented in the oil        | _>  #$“ (approximately 29 US gallons).

Base Analog Base analog is basically a purine or pyrimidine, which is artificial and can be integrated into DNA, giving rise to a changed base pairing. Few of the base analogs are applied therapeutically in the form of anticancer drugs.

Base-Catalyzed Reaction A reaction catalyzed through bases. Quintessential reactions that are basecatalyzed are the Claisen condensation and the aldol reaction, in which the initial step is the removal of a proton in order to provide a carbanion base pairing. The association of the two helical segments of DNA through bonds between the bases that is complementary such as adenine pairing along with thymine and guanine pairing with cytosine. The particular attribute of base pairing sanctions accurate duplicates of the chromosomes and therefore maintains the uniform constitution of the genetic material. When the DNA and RNA pairs together, then the uracil of RNA pairs itself with adenine.

Batch Process A process of production whereinthe reactants are catered into the process in permanent quantities (or batches), instead of a continuous flow. At any specific instant all the material, starting from its construction to the end product, has extended to an explicit phase in the process. Such processes demonstrate difficulties of automation in addition to instrumentation and are inclined to be misuse of energy. For such a reason, batch processing is implemented on an industrial scale at the times when little quantities of valuable or tactical materials are needed, for instance, specialist chemicals or pharmaceuticals.

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Key Concepts in Chemistry

Beckmann Thermometer It refers to a type of mercury thermometer constructed in order to measure slight variations in temperature instead of scale degrees. Beckmann thermometers contain a larger bulb as compared to the common thermometers and have a stem having an internal diameter which is tiny, so that in a stem, a scale of $Z& >  "/        stem in such a manner that the bulk of the mercury could be dissociated from      $Z   >     therefore be designed for any specific range. The Beckmann thermometer has usually been implemented in measuring quantities such as lowering of freezing point along with the rise in boiling point.

Benzene (C6H6) Benzene is a liquid hydrocarbon which has no colors and has a characteristic essence. It is an extremely toxic compound, and continuous inhalation of the vapor is proving to be detrimental. It was initially separated from coal tar, and for a lot many years this was the primary origin of the compound. In recent years, its manufacture is made from hexane; petroleum vapor

  >     $//Z&     pressure of 10 atmospheres.

Figure 10. Benzene ring. Source: Image by Pixabay.

The simplest aromatic hydrocarbon is C6H14~&6H6 + 4H2 Benzene. Refer to aromatic compounds, i.e., the class of unsaturated chemical compounds.

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The constitution of benzene was the concern of substantial speculation during the course of the 19th century. The common problem – which is also referred to as the benzene problem – was that of accommodating and adapting the formula of benzene, C6H6, along with its chemical reactions. The experimental formula is similar to that of acetylene, C2H2, and it may be anticipated that benzene would go through similar reactions. Although, benzene does not possess the same behavior of a compound which has double or triple bonds just like Benzene.

Benzene Carbaldehyde A yellow oily aldehyde having a distinguished odor which is like almond (the compound takes place in almond kernels). Benzene carbaldehyde in many cases can be blended in the laboratory by the common techniques of aldehyde fusion. It can be used in the form of food flavoring as well as in the production of dyes and antibiotics, and can be manufactured in no time through the process of chlorination of methylbenzene (that is toluene) on the methyl group and the succeeding polymerization of dichloroethylene: C6H$CH3 + Cl2~&6H$CHCl2 + 2H2|~&6H$CH(OH)2 + 2HCl C6H$CH(OH)2~&6H$CHO + H2O.

Benzenecarboxylic Acid It is basically a white crystalline carboxylic acid that is usually prevalent naturally in some plants. It is widely used as a food preservative. The carboxyl group (–COOH) directs further substitution onto the benzene ring in the three positions.

Benzpyrene Is a cyclic aromatic hydrocarbon having the structure consisting of five fused benzene ring. It arises in coal tar and is created by partial combustion of some organic compounds. Benzpyrene, which is prevalent in tobacco smoke, has marked carcinogenic properties.

Benzyne It is a short-lived intermediate that exists in some reactions. The ring of six carbon atoms comprises two double bonds and one triple bond (the systematic name is 1,2-didehydrobenzene).

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Key Concepts in Chemistry

Bergius Process A process previously used for creating hydrocarbon fuels from coal. A mixture of powdered coal, heavy oil, and a catalyst was heated with hydrogen at extreme pressure.

Beta-Pleated Sheet It is a type of protein structure in which polypeptide chains run close to each other and are held jointly by hydrogen bonds at right angles to the main chain. The structure is bent in regular ‘pleats.’ Fibers involving this sort of structure are generally composed of amino acids with short side chains. The chains may run in a similar direction (parallel) or opposite directions (antiparallel). It is one of the two basic secondary structures of proteins.

Bioassay An experimental technique used for quantitatively measuring the strength of a biologically active chemical by its effect on living organisms. For instance, the vitamin activity of certain substances can be measured with the help of bacterial cultures. The increase in bacterial numbers is matched against that attained with known standards for vitamins.

Biochemical Oxygen Demand (BOD) The amount of oxygen extracted from natural water by microorganisms that decompose organic waste matter in the water. It is thus a measure of the quantity of organic pollutants present. The biochemical oxygen demand is evaluated by measuring the oxygen amount in a sample of water, storing the sample, and then creating the measurement again five days later.

Biotechnology Is the application of technology to biological processes for industrial, medical, and agricultural purposes. For instance, bacteria such as Streptomycin and Penicillium are used to produce antibiotics and fermenting yeasts produce alcohol in wine and beer manufacture. Recent developments in genetic engineering have allowed the large-scale production of blood serum proteins, hormones, and other medically vital products. Genetic modification of farm crops, and also livestock, offers the possibility of enhanced protection against pests, or products having fresh characteristics, such as novel flavors or prolonged storage properties.

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Biotin A water-soluble vitamin usually found, together with vitamins in the B group, in the Vitamin B Complex. It is extensively distributed in natural foods, kidney, egg yolk, liver, and yeast being good sources. Biotin is needed as a coenzyme for carboxylation reactions in cellular metabolism.

Boiling It is the process by which a liquid is transformed into a vapor and gas by heating at its boiling point. At this temperature, the vapor pressure of the liquid is equivalent to the external pressure, and bubbles of vapor can form within the liquid. The boiling point is always identical for a specific liquid at a given pressure (for reference purposes usually taken as standard pressure).

Boiling Point-Composition Diagram It is generally a diagram for a two-component liquid system that represents both the variation of the boiling point and the composition of the vapor phase as the liquid-phase composition is diverse.

Bomb Calorimeter A device that helps in measuring the energy discharged during the combustion of substances (e.g., fuels and foods). It comprises a strong sealed insulated container in which a recognized amount of the substance is ignited in an atmosphere of pure oxygen. The substance undergoes comprehensive combustion at continuous volume and the resultant rise in temperature can be used to compute the energy released by the reaction. Such energy values (calorific values) are generally quoted in joules per kilogram (J kg–1), previously in calories.

Figure 11. Bomb calorimeter. Source: Image by Wikimedia.

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Key Concepts in Chemistry

Bond Energy The energy comprised in forming a chemical bond. For methane, for example, the energy of the C–H bond is one quarter of the energy indulged for the  &‰}~&}4. It is thus one quarter of the heat of atomization. The bond dissociation energy is a distinctive quantity to the bond energy. It is the energy needed to break down a specific bond in a compound, e.g., CH4~ CH3 + H More strictly, the bond enthalpy can be used.

Bragg Equation An equation is used to infer the crystal structure of a material using data obtained from x-rays directed at its surface. The conditions under which a        ?\    ?       5 ‚  =   ?\  {     %  %  wavelength of the x-rays, and d is the distance between the crystal planes.

Bromine A deep red, reasonably reactive element (symbol Br) belonging to the halogens; i.e., group 17 (previously VIIA) of the periodic table. Bromine is a liquid at room temperature (mercury is the only other element having this property). It arises in tiny amounts in seawater, salt deposits, salt lakes, but is much less abundant than chlorine. A number of organobromine compounds are imperative commercially. At one time the chief use of bromine was as 1,2-dibromoethane. This was added to gasoline to join with the lead created by decomposition of the antiknock agent lead tetraethyl. This use has fallen with the diminution in use of leaded gasoline for environmental reasons. Quantities of bromine are used in polybrominated diphenyl ethers (PBDEs), which are effective ˆ            >

Buckminsterfullerene An allotrope of carbon embracing clusters of 60 carbon atoms bound in a highly symmetric polyhedral structure. The C60 polyhedron has a mixture of hexagonal and pentagonal faces related to the panels on a soccer ball. The molecule was named for the American architect Richard Buckminster Fuller 5#ž“$Y#“ž"= 

{{   5> Fuller).

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The C60 polyhedra are casually called buckyballs. The novel method

 {         \        This also yields less steady carbon clusters, such as C70. It can be made more suitably using an electric arc between graphite electrodes in an inert gas. The allotrope is soluble in benzene, from which it can be crystallized to present yellow crystals. This solid form is recognized by the name fullerite.

Buffer A solution which the pH remains rationally constant when alkalis or acids are added to it; i.e., it acts as a buffer against (small) changes in pH. Buffer solutions usually comprise a weak acid and one of its salts derived from a strong base; e.g., a solution of sodium ethanoate and ethanoic acid. If an acid is added, the H+ reacts with the ethanoate ion (from distanced sodium ethanoate) to form undissociated ethanoic acid; if a base is added, the OH– reacts with the ethanoic acid to form the ethanoate ion and water. The efficacy of the buffering action is identified by the concentrations of the acid–anion pair: K = [H+][CH3COO–]/[CH3COOH] where K is the dissociation constant. Phosphate, tartrate, oxalate, borate, and carbonate systems can also be used for buffer solutions.

Bunsen Burner A gas burner is made up of a vertical metal tube with an adjustable air-inlet hole at the bottom. Gas is permissible into the bottom of the tube and the gas-air mixture is cooked at the top. With too little air the flame is sooty and yellow. Properly adjusted, the burner gives a flame with a pale blue inner core of partly burnt gas, and a nearly invisible outer flame where the gas is  ?[       #$//Z&

Figure 12. Bunsen burner. Source: Image by Pixabay.

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Key Concepts in Chemistry

Burette A piece of apparatus used for the extra of variable volumes of liquid in an orderly and measurable way. The burette is a long cylindrical graduated tube of uniform bore tailored with a stopcock and a small-bore exit jet, allowing a drop of liquid at a time to be enhanced to a reaction vessel. Related devices are used to present measured volumes of gas at controlled pressure in the investigation of gas reactions.

Butane (C4H10) A gaseous alkane obtained either from the gaseous fraction of crude oil or by the ‘cracking’ of heavier fractions. It is believed to be the fourth member of the homologous series of alkanes. Butane is simply liquefied under pressure and its central use is as a portable supply of fuel (bottle gas). It is also used in the engineering production of buta-1,3-diene. The isomeric hydrocarbon CH3CH(CH3)CH3 (2-methylpropane) is also recognized by the name isobutane.

Butanedioic Acid A crystalline carboxylic acid, HOOC(CH2)2COOH, that arises in amber and some plants. It forms during the fermentation of sugar (sucrose).

Butanol Either of two alcohols that are resultant from butane: the primary alcohol butan-1-ol (CH3(CH2)2CH2OH) and the secondary alcohol butan-2-ol (CH3CH(OH)CH2- CH3). It is worth noticing that both are colorless volatile liquids used as solvents.

Butanone It is a colorless volatile liquid ketone. It is produced by the catalytic oxidation of butane and used as a solvent.

Butenedioic Acid Either of the two isomers: Transbutenedioic acid (fumaric acid) is a crystalline compound that are prevalent in certain plants, or Cisbutenedioic acid (maleic acid) is used in the production of synthetic resins. It can be transformed into

Key Concepts in Chemistry

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      #/Z&  %   % loses water to give a cyclic acid anhydride (maleic anhydride).

Butyl Rubber A sort of synthetic rubber made by copolymerizing isobutylene (2-methylpropene, CH3:C(CH3)2) with small sums of isoprene (methylbuta-1,3- diene, CH3:C(CH3)CH:CH2). Before the institution of tubeless tires, butyl rubber was taken into use for inner tubes since it is impervious to air. Consequently, halogenated butyl rubbers were industrialized (halobutyls), which could be treated at higher temperature and vulcanized with other rubbers. Both bromobutyls and chlorobutyls are manufactured. These sorts of rubber are used in tubeless tires bonded to the inner surface of the tire. Other uses are in hoses, sealants, and pond liners.

By-Product A substance obtained at the time of manufacturing of a main chemical product. For instance, propanone was earlier manufactured from propan1-ol, but is now attained as a by-product in the production of phenol by the cumene process.

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Key Concepts in Chemistry

C Calcium Carbide Is a white solid that can be formed by heating coke with calcium oxide at

  5///Z&=`    Y&Ÿ&Y   with water to give ethyne (acetylene; C2H2): CaC2 + 2H2|~& 5|}=2 + C2H2 Previously it was an imperative source of ethyne.

Calorie A unit of energy roughly equal to 4.2 joules. It was previously defined as the energy required surging the temperature of one gram of water by one degree Celsius. As the particular thermal capacity of water changes with temperature, this definition is not detailed. The thermochemical or mean calorie (calTH) is described as 4.184 joules. The international table calorie (calIT) is described as 4.1868 joules. Previously the mean calorie was stated        _       /Z&  #//Z&%  #$Z&      _   #‰$Z&  #$$Z&

   The energy content of a substance can be defined as the energy discharged in burning unit mass. Calorific values can be computed using a bomb calorimeter. They are used to express the efficacy of fuels (in megajoules per kilogram). Calorific values are also applicable to foods (in kilojoules per gram or in calories). Here they gauge the energy formed when the food is oxidized in metabolism.

Calorimeter A device or apparatus used to measure the thermal properties such as specific calorific value, heat capacity, etc.

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Figure 13. Diagram of Bomb Calorimeter. Source: Image by Wikimedia.

Camphor (C10H16O) It is a naturally occurring white organic compound having a characteristic of penetrating odor. It is a cyclic compound and a ketone, previously obtained from the wood of the camphor tree but now made synthetically. Camphor is basically used as a plasticizer for celluloid and as an insecticide against clothes moths.

Cannizzaro Reaction The reaction of aldehydes to give alcohols and acid anions in the presence of strong bases and it is generally seen that the aldehydes taking part in the Cannizzaro reaction do not have hydrogen atoms on the carbon attached to the aldehyde group. For example, in the existence of hot aqueous sodium hydroxide: NaOH + 2C6H$&}| ~ &6H$CH2OH + C6H$COO–Na+. This reaction is a disproportionation, comprising both reduction (to alcohol) and oxidation (to acid). Another instance is the reaction of methanal to give       Œ |}}&}|~&}3OH + HCOO–Na+ The reaction were first labelled by the Italian chemist Stanislao Cannizzaro #ž$"

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Carbanion In an organic reaction, it is an intermediate in which one carbon atom transmits a negative charge. Carbanions may be produced by separating a hydrogen ion from a C–H bond using a base, e.g., from ethanal to form –CH2CHO. They can also be created from organometallic compounds in which the carbon atom is bonded to an electropositive metal.

Carbene          €€™&     >        not form bonds. The simplest instance is methylene, H2C: Some intricate carbenes can be isolated, but most are short-lived intermediates in reactions. In a carbine, the carbon atom has two valence electrons that are not composed of bonding, and carbene species are extremely electrophilic. Typically, they can attack carbon-carbon double bonds to produce cyclopropane derivatives. In addition to it, they can attack single bonds in insertion reactions.     %        |Y}   €Y|Y}  €& ~ €Y|Y C(R2)–H They also has the potential to insert into C–H bonds: R–H + R2C: ~ €Y&5€=Y} €   {    {    > ’ ' in organic synthesis and several methods have been industrialized for producing them in the reaction medium.

Carbide It is basically a compound of carbon having a more electropositive element. The carbides of the elements are classified into: š

š

Ionic carbides that comprise the carbide ion C4–. An instance is aluminum carbide, Al4C3. Compounds of this sort react with water to give methane (they were previously also called methanides). The dicarbides are ionic carbon compounds that comprise the dicarbide ion –C:C–. The best recognized instances are calcium dicarbide, CaC2, also recognized as calcium carbide, or simply carbide. Compounds of this sort give ethyne with water. They were previously called ethynides or acetylides. Ionic carbides are formed with extremely electropositive metals. They are crystalline. Covalent carbides that have giant molecular structures, as in silicon carbide (SiC) and boron carbide (B4C3). These are hard high-melting solids. Apart from this, there are other covalent

Key Concepts in Chemistry

š

39

compounds of carbon (CO2, CS2, CH4, etc.) that have covalent molecules. Interstitial carbides that are interstitial compounds of carbon with transition metals. Titanium carbide (TiC) is an instance. These compounds are all hard high-melting solids having metallic properties. Some carbides (e.g., nickel carbide Ni3C) possess the properties intermediate between those of interstitial and ionic carbides.

Carbocation Ion with positive charge which the charge is mostly restricted on a carbon atom. There are basically two types. Carbonium ions usually have five bonds to the carbon atom and a complete outer shell of 8 electrons. The easiest instance would be the carbonium ion CH$+, which could be seen as formed by adding H+ to methane, CH4, in the similar way that the ammonium ion, NH4 +, is formed from ammonia, NH3. There is, although, a distinction between methane and ammonia in that ammonia has a lone pair of electrons, which it can contribute in forming the NH4+ ion. The    &}$+ (and similar ions) is a transient species, generated in the gas phase by electron bombardment of organic compounds and found in a mass spectrum. The carbonium shape is that of a carbon atom having three hydrogens in a plane and one hydrogen above and one below (a trigonal bipyramid).

Carbohydrate Any of a class of compounds arising widely in nature and having the general formula Cx(H2O)y. (Note that while the name proposes a hydrate of carbon, these compounds are in no way hydrates and have no resemblances to classes of hydrates.) Carbohydrates are usually categorized into two main classes: polysaccharides and sugars. Carbohydrates are both stores of energy and     > ]   >   #$  carbohydrate and animals about 1 percent carbohydrate. The body is able to form up polysaccharides from simple units (anabolism) or breakdown the greater units down to more simple units for freeing energy (catabolism).

Carbon Is the first element of group 14 (formerly IVA) of the periodic table. Carbon is a universal component of living matter and the principal deposits of carbon

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compounds are resultant from living sources; i.e., carbonates (limestone and chalk) and fossil fuels (oil, coal, and gas). It also arises in the mineral dolomite. The element forms only 0.032 per cent by mass of the Earth’s crust. Minute quantities of elemental carbon also arise as the allotropes of diamond and graphite and a third allotrope, buckminsterfullerene (C60), also prevalent.

Figure 14. Carbon atom. Source: Image by Pixabay.

Carbonation It is basically a solution of carbon dioxide in a liquid under pressure, as in carbonated soft drinks. The accumulation of carbon dioxide to compounds, example is the inclusion of CO2 into Grignard reagents.

Carbon Black A superbly alienated form of carbon produced by the imperfect combustion of such hydrocarbon fuels as petroleum oil or natural gas. It is mainly used as a black pigment in inks and as filler for rubber in tire manufacture.

Carbon Cycle The passage of carbon compounds in the environment, one of the main natural cycles of an element. Carbon dioxide in the air is used by green plants in photosynthesis (in which it is mingled with water to form starches

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and sugars). Plants are eaten by animals which exhale carbon dioxide, or when animals and plants die, their leftovers decompose with the production of carbon dioxide. Some plants are overcooked or converted to fossil fuels which are burned, again with the carbon dioxide formation.

Figure 15. Representation of carbon cycle. Source: Image by Flickr.com.

Carbon Dating A method of dating – measuring the age of (typically archaeological) materials that comprises matter of living origin. It is centered on the fact   #‰&%      \    $!"/  %     consistently in the atmosphere as an outcome of cosmic-ray action. The 14C becomes incorporated into living organisms. After the death of the organism, the amount of radioactive carbon lessens exponentially by radioactive decay. The ratio of 12C to 14C is thus a measure of the time passed since the death of the organic material. The method is most appreciated for specimens of up to 20,000 years old, though it has been adapted to measure ages up to 70 000 years. For ages of up to about 8000 years the carbon time scale has been standardized by dendrochronology; i.e., by appraising the 12C:14C ratio in tree rings of known age.

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Carbon Dioxide (CO2) A colorless, odorless, non-flammable gas is created when carbon burns in excess oxygen. It is also created by respiration. Carbon dioxide is prevalent in the atmosphere (0.03 percent by volume) and is transformed in plants to carbohydrates by photosynthesis. In the laboratory, it is made by the action of dilute acid on metal    Q %    \   % such as the manufacture of lime or fermentation. The imperative uses are as a refrigerant (solid carbon dioxide, called dry ice) and in carbonated drinks ? ` >    ?     from the combustion of fossil fuels are thought to back to the greenhouse effect. Carbon dioxide is the anhydride of the weak acid carbonic acid that is formed in water: CO2}|~}2CO3

   2) A colorless poisonous flammable liquid made from sulfur and methane (natural gas). The pure compound is nearly odorless, but CS2 usually has a revolting smell due to the existence of other sulfur compounds. It is used as a solvent and in the production of xanthates in making viscose rayon.

Carbon Fibers Are fibers of graphite that are used, for example, to strengthen polymers and they are made by heating stretched textile fibers and have an orientated crystal structure.

Carbonic Acid (H2CO3) It is a dibasic acid that is formed in small amounts in solution when carbon dioxide dissolves in water: CO2 + H2| ~ }2CO2. It forms two series of salts: carbonates (CO32–), and hydrogen carbonates (HCO3–). The pure acid cannot be isolated.

Carbon Monoxide (CO) A colorless flammable toxic gas made by the incomplete combustion of carbon. In the laboratory, it can be made by dehydrating methanoic acid with concentrated sulfuric acid: HCOOH – H2|~&|` % formed by the oxidation of natural gas or of carbon, or by the water-gas reaction. It is a great reducing agent and is used in metallurgy. It is generally

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seen that carbon monoxide is neutral and only sparingly soluble in water. It is not the anhydride of methanoic acid, although under severe conditions, it can react with sodium hydroxide to form sodium methanoate. It forms metal carbonyls with change metals, and its toxicity is because of its potential to form a complex with hemoglobin (in preference to oxygen).

Carboxyhemoglobin A complex formed when carbon monoxide harmonizes to the iron atom in hemoglobin molecules. The product is steady and hemoglobin has a much better affinity for carbon monoxide than for oxygen. The toxic effect of carbon monoxide is because of its potential to block hemoglobin as an oxygen carrier.

Carboxylate Ion The ion –COO– produced by ionization of a carboxyl group. In a carboxylate ion, the negative charge is usually delocalized over the O–C–O grouping and the two C–O bonds have the identical length, intermediate between that of a single C–O and double C=O.

Carboxylic Acid It is a sort of organic compound comprising the carboxyl group. Simple carboxylic acids have the overall formula RCOOH. Many carboxylic acids arise naturally in plants and (in the form of esters) in oils and fats, therefore another name fatty acids. Carboxylic acids with one COOH group are monobasic, those with two, dibasic, and those with three, tribasic.

Figure 16. Carboxylic acid. Source: Image by Wikimedia.

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Carcinogen Carcinogen is any substance that causes living tissues to become cancerous. Chemical carcinogens comprise several organic compounds, e.g., hydrocarbons in tobacco smoke, as well as inorganic ones, e.g., asbestos. Carcinogenic physical agents comprise x-rays, ultraviolet light, and radioactive materials. Some viruses (e.g., hepatitis B) are also carcinogens. Many carcinogens are mutagenic, i.e., they cause transitions in the DNA; dimethylnitrosamine, for instance, methylates the bases in DNA. A potential      [     

Carius Method It is a method in quantitative analysis for defining the amounts of halogens, sulfur, and phosphorus in organic compounds. The compound is heated with concentrated silver nitrate and nitric acid in a sealed tube. The silver compounds formed are weighed and separated.

Carnot Cycle It is the idealized reversible cycle of four operations arising in a perfect heat engine. These are the successive adiabatic compression, adiabatic expansion, isothermal expansion, and isothermal compression of the working substance. The cycle returns to its preliminary pressure, temperature, volume, and transfers energy to or from mechanical work. The efficacy of the Carnot cycle is the maximum achievable in a heat engine.

Carotenoid It is any of a group of yellow, red pigments or orange comprising the xanthophylls and carotenes. They are found in all photosynthetic organisms, where they function largely as accessory pigments in photosynthesis, and in some animal structures, e.g., feathers. They contribute, with anthocyanins, to the autumn colors of leaves because of the green pigment chlorophyll that typically masks the    %  {                ˆ %%   &    >     { \ violet region of the spectrum. Carotenes are hydrocarbons.        „\            carrots whose molecule is divided into two indistinguishable portions to

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yield vitamin A during digestion in vertebrates. Xanthophylls look like carotenoids but embrace oxygen.

Casein It is a phosphorus comprising protein that arises in cheese and milk. It is simply digested by young mammals and is their main source of phosphorus and protein. The protein has been used for making certain items, such as buttons and billiard balls, and has also been used to make glue. These uses have failed due to the competition from synthetic polymers.

Catabolism It is all the metabolic reactions that break down intricate molecules to simpler compounds. The primary objective of catabolic reactions is to offer energy.

Catalyst It is a substance that changes the rate of a chemical reaction without itself being altered chemically in the reaction. The catalyst can, though, undergo physical change; for instance, large lumps of the catalyst can, without loss in mass, be transformed into a powder. Small amounts of catalyst are usually adequate to enhance the rate of     >          a negative catalyst lessens it. Homogeneous catalysts are those that act in the same phase as the reactants (i.e., in liquid systems and gaseous). For instance, nitrogen(II) oxide gas will catalyze the reaction between oxygen and sulfur(IV) oxide in the gaseous phase. Heterogeneous catalysts act in a distinctive phase from the reactants.    %>{5  =   [      of oil (liquid). In raising a reaction rate, a catalyst offers a new pathway for which the rate-determining step has a lesser activation energy in comparison to the uncatalyzed reaction.

Catalytic Converter A device attached to the exhaust system of gasoline-fueled vehicles to eliminate pollutant gases from the exhaust. It comprises a honeycomb structure (to offer maximum area) coated with palladium, platinum, and rhodium catalysts. Such devices can transform oxides of nitrogen to

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nitrogen, carbon monoxide to carbon dioxide, and unburned fuel to water and carbon dioxide.

Catalytic Cracking The conversion, using a catalyst, of long-chain hydrocarbons from the petroleum refining into more useful shorter-chain compounds such as those arising in gasoline and kerosene.

Cationic Resin It is an ion-exchange material that can trade cations, such as Na+ and H+, for ions in the surrounding medium. Such resins can be used for a broader range of purification as well as analytical purposes. They are usually formed by adding a sulfonic acid group (–SO3–H+) or a carboxylate group (–COO–H+) to an stable polyphenylethene resin. A typical exchange reaction is: resin–SO3 –H+ + NaCl = resin–SO3 –Na+ + HCl   >        ?      ?  cations of identical size having the same charge. Such mixtures can be attached to cationic resins and progressive elution will recover them in order of lessening ionic radius.

Cell It is a system having two plates (electrodes) in a conducting liquid (electrolyte). An electrolytic cell is used for making a chemical reaction by passing a current through the electrolyte (i.e., by electrolysis). A voltaic (or galvanic) cell produces an E.M.F. by chemical reactions at each electrode. Electrons are conveyed to or from the electrodes, giving each a net charge.

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Figure 17. Cell representation. Source: Image by Wikimedia.

Cellulose Acetate (Cellulose Ethanoate) It is a polymeric substance that is made by acetylating cellulose using a mixture of ethanoic acid, sulfuric acid, and ethanoic anhydride. It is used in plastics, in acetate rayon, and in acetate film.

Celsius Scale A temperature scale in which the temperature of melting pure ice is taken /Z      #//Z5     =  &5Z&=_>   {>  {    centigrade scale until 1948, when the present name became official. It is named for the Swedish astronomer Anders Celsius (1701–44). Celsius’

  5#!‰= >5% /Z      #//Z   =

Centrifugal Pump A device commonly used for conveying fluids around a chemical plant. Centrifugal pumps generally have a set of blades rotating inside a fixed circular casing. As the blades rotate, the fluid is propelled out of the pump along a pipe. Centrifugal pumps do not yield high pressures, but they have

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the benefit of being comparatively cheap because they are naive in design, work at high speeds, and have no valves. In addition, they are not damaged if a blockage develops.

Centrifuge An instrument for rapid rotation of a container, intended to accelerate the sedimentation of suspensions or the separation of two immiscible liquids.

CGS System A unit system based on the centimeter, gram, and second as the fundamental mechanical units. This system was utilized extensively in early scientific work, but it is now nearly entirely obsolete in favor of SI units.

Chain A chain of atoms is formed when two or more atoms in a molecule create bonds with each other. This chain can either be straight, with each atom introduced at the end of the chain, or it can be branched, with one or more smaller side chains branching off the main chain of atoms.

Chain Reaction A self-sustaining chemical reaction is made up of a series of steps, with each step started by the one before it. The reaction between hydrogen and chlorine is an example: Cl2 ~&š}2&š~}&}š}š&2 ~}&  &š }š ~ }2 &š ~ &2. The breakdown of chlorine molecules into atoms is the first stage of chain initiation, which is preceded by two chain propagation reactions. Two molecules of hydrogen chloride are formed, and the chlorine atom that is expelled is prepared to react with more hydrogen. The final steps, chain termination, bring the reaction to a halt. Certain forms of free-radical polymerization processes rely on chain reactions.

Chalcogens The elements in periodic table group 16 – oxygen, Sulphur, selenium, tellurium, and polonium.

Charcoal Amorphous carbon is produced by heating wood or other organic material in the absence of air. Activated charcoal refers to carbon that has been heated

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to remove the absorbed gas. It is used to absorb gases as well as to remove contaminants from liquids.

Chelate It is a metal coordination complex wherein one ligand coordinates to the same metal ion at two or more sites. The resultant complex is made up of rings of atoms, one of which is a metal atom. 1,2-diaminoethane (H2NCH2CH2NH2), which is capable of binding both of its amine groups to the same atom are an example of a chelating agent. It is a form of a bidentate ligand (meaning it has two “teeth”). Another chelating agent is EDTA, which can form up to six bonds. The term chelate is derived from the Greek word for “claw.”

Chemical Bond It is a link between atoms, resulting in an aggregate with enough stability to be considered an independent molecular species. Covalent bonds, electrovalent (ionic) bonds, coordinate bonds, and metallic bonds are examples of chemical bonding. Hydrogen bonds and van der Waals forces are not considered true chemical bonds.

Figure 18. Examples of chemical bonds. Source: Image by Wikimedia.

Chemical Combination Laws It is a set of chemical laws that emerged in the late 18th and early 19th centuries as a result of the acknowledged necessity of quantitative (rather than qualitative) research of chemical reactions. The laws are as follows: š

the law of conservation of mass (matter);

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Key Concepts in Chemistry

š š š These (1808).

     5=   ] the law of multiple proportions; and the law of equivalent (or reciprocal) proportions. laws were crucial in Dalton’s formulation of his atomic theory

Chemical Dating It is a method to determine the age of an archaeological specimen using chemical analysis in which compositional changes have occurred over time. The amount of fluorine in buried bone, for instance, serves as an indicator of its age since phosphate in the bone has gradually been replaced by fluoride ions from groundwater. Another dating approach is based on the fact that amino acids are optically active in living organisms. After death, a delayed racemization reaction takes place resulting in a mixture of L- and D-isomers. The relative proportions of L- and D-amino acids contained in bones can be used to correctly calculate their age.

Chemical Engineering The branch of engineering involved with designing and maintaining a chemical plant, as well as its resistance to temperature and pressure variations, corrosion, and wear. It allows laboratory procedures that produce grams of material to be expanded up to a large-scale factory that produces tonnes of material. By connecting the proper unit processes and researching variables such as heat and mass transfer, separations, and distillations, chemical engineers are able to design large-scale chemical processes.

Chemical Equation It is a chemical formula-based approach of representing a chemical process. The reactants are presented on the left side of the equation, while the products are given on the right. A directing arrow or arrows, or an equals sign, separates the two segments. A number before a formula (known as a stoichiometric coefficient) specifies the number of molecules of that material involved. The equation must be balanced, which means that the number of atoms in each element must be the same on both sides of the equation.

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Chemical Reaction A reaction that occurs when one or more elements or chemical compounds (the reactants) interact to form a new substance or substances (the products).

Chiral

Figure 19. Chiral phosphoric acid. Source: Image by Wikimedia.

It is a possessing the property of chirality. Lactic acid, for instance, is a chiral compound as it contains two potential structures that are incapable of being superimposed.

Chirality The attribute of occurring in both left and right-handed forms; that is, formations that cannot be superposed. In chemistry, the word refers to the presence of optical isomers.

Chirality Element It is a chirality-inducing component of a molecule. A chirality center, which is an atom connected to four separate atoms or groups, is the most frequent sort of element. This is also known as an asymmetric atom. A chirality axis in a molecule is less common, as in the case of certain substituted allenes of the type R1R2C=C=CR3R4. Due to the nature of the double bonds, the R1 and R2 groups in this compound and the R3 and R4 groups do not lie in the same planes. The chirality axis runs parallel to the C=C=C chain. It is also possible to have molecules with chirality planes.

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Chitin

Figure 20. An image representing chitin. Source: Image by Wikipedia.

A nitrogen-containing heteropolysaccharide is present in the cell walls of most fungi and in certain mammals. It is N-acetylglucosamine polymer. It is made up of multiple glucose units, each with one of the hydroxyl groups replaced with an acetylamine group (CH3CONH). The cuticle of arthropods is impregnated with chitin in its outer layers, making the exoskeleton stiffer. `       {    ˆ?% as well as lightweight and waterproof. The chitinous plates are either    ˆ?  { %   requirements. The plates cannot develop after they have been laid down and are broken down at each molt. Chitin is also present in the hard parts of a variety of different animal species.

Chloramine (NH2Cl)

Figure 21. Chloramine (NH2Cl). Source: Image by Wikipedia.

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A colorless liquid produced by combining ammonia with sodium chlorate (I) (NaOCl). It is made as an intermediate in the hydrazine synthesis process. Chloramine is highly unstable and rapidly degrades into ammonium chloride and nitrogen trichloride.

Chlorination It is the treatment using chlorine, such as using chlorine to disinfect water.

Chlorine It is a green and reactive gaseous element of the halogens, belonging to group 17 (previously VIIA) of the periodic table. It can be found in seawater,   {%   %Œ & ` {  //$$ percent of the Earth’s crust. Chlorine is a strong oxidizer and can only be freed from its salts by strong oxidizing agents like manganese(IV) oxide, potassium permanganate(VII), or potassium dichromate; it should be kept in mind that sulfuric acid is insufficiently oxidizing for liberation of chlorine from chlorides. Chlorine is manufactured industrially by electrolysis of brine, and sometimes, chlorine is retrieved by high-temperature oxidation of waste hydrochloric acid. Chlorine is widely utilized, both as an element in the creation of chlorinated organic solvents, as well as in the production of polyvinyl chloride (PVC), the most common thermoplastic being used nowadays, and as hypochlorites for bleaching.

Chlorobenzene A colorless liquid produced from the catalytic reaction of chlorine and benzene or through the Raschig process. It can be transformed to phenol       5"//Z&  //    =    with sodium hydroxide. It is also employed in the production of other organic molecules.

Chloroethane A gaseous substance formed by adding hydrogen chloride to ethene. Uses include refrigerant and local anesthetic.

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Key Concepts in Chemistry

Chloroethanoic Acid (chloroacetic acid; CH2ClCOOH) A colorless crystalline solid created by utilizing red phosphorus to replace one of the hydrogen atoms in the methyl group of ethanoic acid with chlorine. Given the electron-withdrawing effect of the chlorine atom, it is a stronger acid than ethanoic acid. The synthesis of dichloroethanoic acid (dichloroacetic acid, CHCl2COOH) and trichloroethanoic acid (trichloroacetic acid, CCl3COOH) is done in the same way. The potency of the acid grows as the amount of chlorine atoms present increases.

Chloroethene (Vinyl Chloride; H2C:CHCl) It is a gaseous organic chemical that is involved in the production of PVC (polyvinyl chloride). It is produced through the reaction of ethyne and hydrogen chloride with a mercury(II) chloride catalyst: C2H2  }& ~ H2C:CHCl. Dichloroethane is an alternate source that takes advantage of the available supply of ethene: H2C:CH2+ Cl2~&}2Cl.CH2&~}2C:CHCl.

Choline

Figure 22. Choline-cation-3D-balls. Source: Image by Wikimedia.

It is an amino alcohol that is frequently categorized as a vitamin B complex member. It can be generated in humans from lecithin via bowel putrefaction, but it is needed as an important vitamin by some animals and microbes. It disperses fat from the liver or stops it from accumulating too much. Its ester acetylcholine aids in nerve impulse transmission.

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Chromatography

Figure 23. Chromatography tank. Source: Image by Wikimedia.

A method for separating or analyzing complicated mixtures. There are several related processes, all of which rely on two phases: a mobile phase, which can be a liquid or a gas, and a stationary phase, which can be a solid or a liquid held by a solid. The mobile phase transports the sample to be separated or analyzed through the stationary phase. The stationary phase absorbs or dissolves different components of the mixture to varying degrees,    ˆ  >   The components are separated in this manner. Based on the phases utilized and the nature of the partition process between mobile and stationary phases, there are numerous types of chromatography. The two basic types of chromatography are column chromatography and planar chromatography.

Chromophore A collection of atoms in a molecule that is responsible for the compound’s color. A chromophore is typically a collection of atoms with delocalized electrons.

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CIP System (Cahn–Ingold–Prelog System) It is a technique for generating a sequence rule that is applied in the absolute description of stereoisomers in the R–S convention or the E-Z convention. The rule is to select atoms that are directly bound to a chiral center (or to a double bond). Priority is given to the group in which this atom has the most proton numbers. In HCClBr(NH2), for example, the priority sequence is Br > Cl > NH2 > H. When two atoms have the same substituents, the substituents with the greater proton number take priority. Thus, in C(NH2)(NO2)(CH3) (C2H6), NO2 > NH2 > C2H6 > CH3 is the priority order. The method was named after British chemists Robert Cahn (1899–1981) and Sir Christopher Ingold (1893–1970), as well as Bosnian–Swiss chemist Vladimir Prelog (1906–1998).

Citric Acid A dibasic carboxylic acid that is white and crystalline, and found in plant and animal cells. It can be found in a variety of fruits, notably citrus fruits. The chemical name is 2-hydroxypropane-1,2,3-tricarboxylic acid, while HOOCCH2C(OH)(COOH)CH2COOH is the formula.

Clathrate (Enclosure Compound)

Figure 24. Clathrate compound. Source: Image by Wikipedia.

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It is a compound wherein tiny molecules (guests) are entrapped inside the lattice of a crystalline (host) compound. When suitable host chemicals crystallize in the presence of appropriately sized molecules, Clathrates are generated. While the name “clathrate compound” is in common use, they are not real compounds as no chemical bonds are formed and the guest molecules interact.

Coal A black mineral composed primarily of carbon, and is utilized as a fuel and a source of organic compounds. It is the fossilized remains of plants that grew during the Carboniferous and Permian periods and were buried underground under enormous pressures. Coal is divided into different categories based on the amount of carbon it contains.

Coal Gas It is a fuel gas produced by heating coal with a restricted amount of air. It is mostly made up of hydrogen and methane, with traces of carbon monoxide (which makes the gas highly poisonous). Byproducts include coal tar and coke. Coal gas was a popular fuel in various countries during the nineteenth and early twentieth centuries.

Coal Tar

Figure 25. Coal tar. Source: Image by Flickr.

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Key Concepts in Chemistry

It is a tar which is formed when coal is heated in the absence of oxygen. It is a combination of several organic molecules, including benzene, toluene, and naphthalene, as well as free carbon.

Cocaine An alkaloid derived from the dried leaves of Erythroxylon coca, a South American shrub. It is both a stimulant and a narcotic. Use of cocaine is prohibited in several countries.

Codeine It is derived from morphine, methylmorphine. It is used as an analgesic and has a lower potency than morphine. In the United States, it is a regulated drug.

Coenzyme It is any of a class of molecules (tiny in comparison to the size of an enzyme) that allow enzymes to perform catalytic activity. Niacinamide adenine dinucleotide (NAD) and ubiquinone are two examples (coenzyme Q). In the absence of an enzyme, some coenzymes can catalyze reactions, but the rate of reaction is not as fast as when performed in the presence of a catalyst. Since it undergoes chemical change throughout the reaction, a coenzyme is not considered a true catalyst.

Coenzyme A (CoA)

Figure 26. An image representing Coenzyme A (CoA). Source: Image by Wikipedia.

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A nucleotide with an active –SH group that is easily acetylated to CoAS– COCH3 (acetyl CoA). The two-carbon units that feed the Krebs Cycle are obtained from acetyl CoA. It is formed as a result of glycolysis and the decomposition of fatty acids and some amino acids. It also serves as an important step in the creation of lipids and other anabolic processes.

Cofactor It is a non-protein substance that aids an enzyme in its functions. Cofactors might be cations or organic compounds called coenzymes. In contrast to enzymes, they are typically heat stable. A holoenzyme is formed when a catalytically active enzyme makes a complex with a cofactor. An apoenzyme is an enzyme that does not have a cofactor.

Coherent Units Systems or unit subsets (e.g., SI units), where the units obtained are multiplied or divided together by the base units without any numerical factor.

Collagen Fibrous connective tissue protein commonly found in bone, skin, and cartilage. It is the most prevalent protein found in higher vertebrates. &       "$”%##”  %#” % and trace amounts of certain other amino acids. The amino acid sequence is very regular, with glycine constituting almost every third residue. Collagen is chemically inert and insoluble, implying ionic bonding immobilizes its reactive side groups. Collagen fibrils are extremely complicated and can have a range of orientations varying on the biological function of the connective tissue in question.

Colligative Properties It is a class of properties of solutions that are determined by the number of particles present instead of the type of particles. These properties include: š š š š

The reduction of vapor pressure An increase in the boiling point. A decrease in the freezing point. Osmotic pressure.

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The explanation for these highly associated phenomena is based on intermolecular forces and particle kinetic behavior, which are qualitatively comparable to those used to develop the kinetic theory of gases.

Collimator

Figure 27. Collimator. Source: Image by Wikimedia.

It is a method of creating a parallel beam of radiation to be used in a spectrometer or other device. A lenses and slits system are used.

Colloid Colloid is a heterogeneous system where the interfaces between phases, while not visible, play a vital role in shaping the system’s features. Colloids have three important properties: š

š š

They contain particles, which are often made up of a high number of molecules and comprise the distinguishing unit or disperse phase. The particles are dispersed throughout a continuous medium (the continuous phase).    [          and the medium; the stabilizer is frequently a polar group.

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Particles in the disperse phase generally have sizes in the 10–6– 10–4 mm range.

Colorimetric Analysis It is calculation of the concentration of a colored solute using the intensity of the color through a quantitative evaluation. Standard solutions can be used to compare the test solution.

Combustion It is a reaction with oxygen that generates heat and light. Solids and liquids combust when they emit flammable vapor, which combines with oxygen in the gas phase. Combustion reactions are often characterized by a complex sequence of free-radical chain reactions. Excited atoms, molecules, or ions generate light. It is produced by little incandescent carbon particles in highly luminous flames. The word is sometimes used to describe slow reactions with oxygen, as well as reactions with other gases (for example, certain metals ‘burn’ in chlorine).

Complex (Coordination Compound) It is a substance wherein molecules or ions build coordinate bonds with a metal atom or ion. The coordinating species (known as ligands) possess lone pairs of electrons that they can give to the metal atom or ion. They could be molecules like ammonia or water, or negative ions like Cl– or CN–. The resulting complex could either be neutral or a complex ion. For example: Cu2+ + 4NH3~¤&5Œ}3)4]2+ Fe3+ + 6CN–~¤ 5&Œ=6]3– Fe2+ + 6CN–~ [Fe(CN)6]4–

Component It is a separate chemical substance in a combination that is not undergoing chemical reactions. A mixture of ice and water, for instance, has one component; a mixture of nitrogen and oxygen has two components. When chemical reactions take place between the components of a mixture, the number of components is given as the number of chemical substances present minus the number of equilibrium reactions occurring. As a result, the system N2 + 3H2~Œ}3 is a two-component system.

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Key Concepts in Chemistry

Compound Compound is a chemical reaction that combines atoms from different elements to produce a substance in which the ratio of combining atoms remains constant and is unique to that substance. The constituent atoms cannot be separated physically and the compounds must be generated or modified by a chemical reaction. The presence of a compound does not mean that it is stable. Many compounds have lives shorter than a second.

Concentrated It is a solution with a relatively high solute amount in the solvent. The term is always used relatively. Concentrated sulfuric acid, for example, may contain 96 percent H2SO4, but concentrated potassium chlorate may include as little as 10 percent KClO3.

Concentration Concentration is the amount of substance in a solution per unit volume or mass. The amount of substance (in moles) per cubic decimeter (liter) is referred to as molar concentration. Mass concentration is defined as the mass of a solute per unit volume. The amount of substance (in moles) per kilogram of solute is referred to as molal concentration.

Concerted Reaction This is a reaction that occurs in a single stage as opposed to a number of simple phases. There is a transition state in a concerted reaction where bonds are formed and broken at the same time. The SN2 mechanism in nucleophilic substitution is one example.

Condensation Reaction It is a reaction wherein two molecules are added, followed by the elimination of a smaller molecule, generally water. Condensation reactions (addition– elimination reactions) are common when aldehydes and ketones react with certain nucleophiles. Generally, nucleophilic addition occurs at the carbonyl group’s C atom, followed by water elimination.

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Conducting Polymer

Figure 28. Conducting polymer. Source: Image by Wikipedia,

It is a form of organic polymer that is an electricity conductor in the same way that metals are. Crystalline solids with conjugated unsaturated carbon–carbon bonds are known as conducting polymers. In theory, they offer lighter and less expensive substitutes to metallic conductors.

Conductiometric Titration It is a titration in which the electrical conductance is measured continuously all through the titrant addition and well beyond the equivalence point. In place of the typical end-point determination via indicators, this method is used. The operation takes place in a conductance cell, a component of a resistance bridge circuit. The approach is based on the fact that ions have varying ionic mobilities, with H+ and OH– having especially high values. The approach is particularly beneficial for titrations of weak acid–strong base and strong acid–weak base, where color-change titrations are inconsistent.

  Configuration is the arrangement of electrons around an atom’s nucleus. Configurations are represented using symbols that include: 1. Integer representing the primary quantum number’s value (shell number). 2. Lowercase letter denoting the value of the azimuthal quantum number (l), such as s for l = 0, p for l = 1, d for l = 2, and f for l = 3. 3. Numerical superscript      %  #%"%"$ The ground state electronic configuration which means the most stable or lowest energy state can thus be written as He, 1s2; N, 1s22s22p$. Elements

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are typically shortened by employing an inert gas to represent the ‘core,’ for example, Zr has the configuration [Kr]4d2$2.

Conformation A molecule’s shape that results from the typical rotation of its atoms or groups around single bonds. A conformer (or rotamer) is any of the possible conformations that can be generated, and there will be an unlimited number of these possibilities, varying in the angle between specific atoms or groups on nearby carbon atoms. The term “conformer” is often used more specifically to refer to hypothetical conformations with low energies, such as the boat and chair conformations of cyclohexane. Consider the dihedral angle between a bond from one carbon atom and a bond from the other carbon atom when evaluating conformations about a single bond.

Conjugated Compounds with alternating double and single bonds in their structure. But1,3-ene (H2C:CHCH:CH2) is an example of a conjugated compound. The electrons in the double bonds in such compounds delocalize over a portion of the molecule.

Conjugated Protein

Figure 29. Conjugated protein. Source: Image by Wikipedia,

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A protein which, when hydrolyzed, produces amino acids as well as other organic and inorganic compounds. These are simple proteins that have been fused with non-protein groups (prosthetic groups).

Constant-Boiling Mixture A basic finding with most liquids is that the vapor phase above a liquid is richer in the more volatile component (a variation from Raoult’s law). As a result, most liquid mixes exhibit a consistent increase in boiling point as the liquid is further distilled. A point is attained in distillation when a steady boiling mixture or azeotrope distils over. Further fractionation of        ¥ 5#//Z&=     5 !ž"Z&=    ?   [   ?     boiling points, with the azeotrope containing 4.4 percent water and boiling !ž#Z&

Continuous Process It is a manufacturing process wherein the raw materials are fed into the plant on a continuous basis. As they pass through the machine, the reactions take place, resulting in a constant flow of product. Only a little amount of material is present at any given time in the process, yet material from all stages of the reaction is present. Example of a continuous process is the fractional distillation of crude oil. Such processes are generally simple to automate and can thus be employed to develop a product at a low cost. The downsides of continuous processing include that it usually caters to a high demand, and the plant is expensive to establish and cannot typically be used for other purposes.

Continuous Spectrum A spectrum made of a continuous range of radiated or absorbed light. Hot solids produce continuous spectra in the infrared and visible ranges.

Coordinate Bond (Dative Bond) A covalent bond where the bonding pair is seen as being formed by the donation of a lone pair from one species to another species that acts as an electron acceptor. The definition covers examples such as the ‘donation’ of the ammonia molecule’s lone pair to H+ (an acceptor) to create NH4+ or to Cu2+ to create [Cu(NH3)4]2+.

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Coupling It is a chemical reaction that occurs when two groups or molecules come together. The formation of azo compounds is one such example.

Covalent Bond

Figure 30. Covalent bond. Source: Image by Wikipedia.

A bond created between two atoms by the sharing of an electron pair. The covalent bond is generally shown as a line, so H–Cl denotes that there is an electron pair produced by electrons of opposing spin between the hydrogen atom and the chlorine atom, meaning that the binding forces are strongly localized between the two atoms. Molecules are made up of atoms that are held together by covalent bonds with energies of the order of 103 kJ mol–1. Modern bonding theory views electron pairing as the interaction of electron (atomic) orbitals, and the covalent bond is described in terms of both ‘bonding’ and ‘antibonding’ molecular orbitals.

Covalent Radius It is the presumed radius of an atom, when involved in a covalent bond. This is just half the measured internuclear distance for homonuclear diatomic molecules (e.g., Cl2). Substitution strategies are employed for heteroatomic compounds. For example, the internuclear distance of bromine fluoride (BrF) is approximately 180 pm, so using 71 pm for fluorine’s covalent radius (from F2), 109 pm for bromine is attained. 114 pm is the accepted value.

Creosote A colorless and oily liquid distilled from wood tar that contains phenols and is used as a disinfectant. Creosote oil, a dark brown liquid extracted from

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coal tar and used to preserve timber, also bears the name. It also contains phenols, as well as some methylphenols.

Critical Point The temperature and pressure parameters under which a liquid heated in a closed vessel becomes indiscernible from the gas or vapor phase. By exerting pressure at temperatures below the critical temperature (Tc), the substance can be liquefied; at temperatures over Tc, this is not feasible. Each material has a critical point; for example, carbon dioxide has a critical point "##Z& !"/   

Critical Pressure The lowest pressure required to cause a gas to liquefy at its critical temperature.

Critical Temperature It is the maximum temperature at which a gas can be liquefied by exerting pressure but above which no amount of pressure will result in liquefaction. Q   %        ? 5"##Z&=     5#‰‰Z&=% > critical temperatures beyond room temperature and have been observed in the liquid state for many years. For gases with extremely low critical   5  ? % ? Y##žZ&    Y#‰ŽZ&=% liquefaction proved substantially more difficult

Crown Ether A compound with a large ring made up of –CH2–CH2–O– units. For example, the formula for 18-crown-6 is C12H24O6 (six CH2CH2O units). The rings of these compounds are not planar; the name derives from the molecule’s structure. These cyclic ethers’ oxygen atoms can align to central metal ions or other positive ions (e.g., NH4+). Crown ethers have a variety of applications in analysis, mixture separation, and as catalysts. Cryptands are related chemicals that have ether chains connected by nitrogen atoms to form a three-dimensional cage structure. They behave similarly to crown ethers, but create more firmly bonded complexes.

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Crystal It is a solid substance with a distinct geometric shape. A crystal has definite edges and fixed angles between its faces. If the faces can reflect light, the crystal will sparkle. The regular groupings of particles (atoms, ions, or molecules) in the crystal induce the constant angles. When a huge crystal is fractured, smaller crystals arise. In the solid state, the atoms, ions, or molecules of a substance create a distinct regular array. The angles and faces of these particles have a direct relationship to their arrangement.

Crystal Habit It is the structure of a crystal. The habit is determined by how the crystal developed, i.e., the relative rates of development of distinct faces.

Crystalline It is denoting a material that crystallizes. Even if crystalline substances do not occur as geometrically regular crystals, they have a regular interior arrangement of atoms. Lead and other metals are crystalline, for instance. These compounds are made up of clumps of microscopic crystals.

Crystallite It is a tiny crystal with the capacity to develop in size. In mineralogy, it is commonly used to describe specimens containing accumulations of many minuscule crystals of undefined chemical composition and crystal structure.

Crystallization

Figure 31. Crystallization process. Source: Image by Wikipedia.

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It is the formation of crystals. Crystallization tends to take place when a substance begins to cool from a gaseous or liquid state to a solid state. A solution saturated with a solute will also crystallize.

Crystallography It is the analysis of crystal formation, structure, and characteristics.

Crystalloid A substance which is not a colloid and so cannot penetrate a semipermeable membrane.

Crystal Structure A crystal’s specific repeating arrangement of atoms, molecules, or ions. The term ‘structure’ denotes the interior arrangement of particles rather than their exterior appearance.

Crystal System A crystal classification determined by the shape of its unit cell. If the unit cell is a parallelepiped having lengths a, b, and c and the angles between   <5  =%„5   =% †5   =%     ]<„†“/Z

CS gas

Figure 32. An image showing cylinder of CS gas. Source: Image by Wikipedia.

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It is a white organic chemical which is a nasal irritant and is employed as a tear gas in powder form for crowd control.

Cumene Process An industrial procedure for producing phenol from isopropyl benzene (cumene), which is produced by passing benzene vapor and propene             5$/Z&  "/   = &6H6 + CH2:CH(CH3= ~ &6H$CH(CH3). Air oxidizes isopropyl benzene to form a ‘hydroperoxide’: C6H$C(CH3) 2–O–O–H. Dilute acid hydrolyzes this to phenol (C6H$OH) and propanone (CH3COCH3), both of which are useful by-products.

Curie A radioactivity unit equal to the amount of a specific radioactive substance that produces 3.7 × 1010 disintegrations each second, which is the number of disintegrations generated by one gram of radium.

Cyanocobalamin (Vitamin B12) It is one of the vitamins of the water-soluble B group. It has a complex organic ring structure with a single cobalt atom at the core. Animal-derived foods are the only significant dietary source. As the vitamin is essential for the production of red blood cells, a lack of it results in pernicious anemia.

Cyanohydrin An additional compound generated by the reaction of an aldehyde or ketone     €&}5|}=5&Œ=5    = €€™&5|}= (CN) (from a ketone) are the general formulas. Cyanohydrins hydrolyze quickly to hydroxycarboxylic acids. For example, 2-hydroxypropanonitrile (CH3- CH(OH)(CN)) is hydrolyzed to 2-hydroxypropanoic acid (CH3CH(OH)(COOH).

Cyclic Compound A compound made up of atoms arranged in a ring. The compound is homocyclic when all of the atoms in the ring are the same whereas it is heterocyclic when different atoms are involved.

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Cycloalkane It is a saturated cyclic hydrocarbon with the general formula CnH2n that consists of a ring of carbon atoms, each bearing two hydrogen atoms. Cyclopropane (C3H6) and cyclobutane (C4H8) are both extremely reactive and possess strained rings. Other cycloalkanes have characteristics similar to alkanes, but are often less reactive than their equivalent alkane.

Cyclohexane (C6H12)

Figure 33. Cyclohexane (C6H12). Source: Image by Flickr.

A colorless liquid alkane used as a solvent and in the manufacturing of hexanedioic acid (adipic acid) for the synthesis of nylon. Cyclohexane is produced by reforming longer chain hydrocarbons occurring in crude oil fractions.

Cyclopentadiene A cyclic hydrocarbon produced by the cracking of petroleum. The molecules are composed of a five-membered ring with two carbon-carbon double bonds and one CH2 group. It is a non-benzenoid aromatic that makes the  >   &$}$Y      

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Cytidine (Cytosine Nucleoside) A nucleoside produced when cytosine is bonded to D-ribose through a „\  

Cytochrome It is a class of heme-containing conjugated proteins that serve as intermediates in the electron-transport chain. There are four major classes, denoted by the letters a, b, c, and d.

Cytokinin

Figure 34. Cytokinin Biosynthesis. Source: Image by Wikimedia.

It is a group of plant hormones that promotes cell proliferation, nucleic acid metabolism, and root-shoot connections. Cytokinin are frequently purine derivatives, such as kinetin (6-furfuryl aminopurine), a synthetic cytokinin commonly employed in research, and zeatin, a purine derivative occurring in maize cobs.

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Cytosine A nitrogenous base that is present in DNA and RNA. The ring structure of cytosine is pyrimidine.

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D D-Block Elements It is the transition elements of the first, second, and third long periods of the periodic table, i.e., Sc to Zn, La to Hg, and Y to Cd. They are so known because in general they have inner d-levels with configurations of the type (n – 1)dxns2 where x = 1–10.

DDT (Dichlorodiphenyltrichloroethane)

Figure 35. DDT (dichlorodiphenyltrichloroethane). Source: Image by Wikipedia.

It is a colorless crystalline organic compound that was once extensively used as an insecticide. It is extremely steady and tends to accrue in the soil, and passes up the food chain to amass in the fatty tissues of carnivorous animals. Its systematic name is 1,1-bis(4-chlorophenyl)- 2,2,2-trichloroethane.

Decomposition It is the process in which a compound is wrecked down into compounds with simpler molecules.

Decrepitation It is the process in which a crystalline solid produces a crackling noise on heating, generally due to the loss of water of crystallization.

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Degenerate It is describing different quantum states that have the same energy. For example, the five d orbitals in a transition metal atom all have the identical energy but distinctive values of the magnetic quantum number m. Differences in energy arise if a magnetic field is pertained or if the arrangement of ligands around the atom is not symmetrical. The degeneracy is then said to be ‘lifted.’

Degradation It is basically a type of chemical reaction comprising the decomposition of a molecule into simpler molecules, generally in stages. The Hofmann Degradation of amides is an instance.

Dehydration

Figure 36. Draught because of dehydration. Source: Image by Pixabay.

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Removal of water from a substance. Removal of the elements of water (for instance oxygen and hydrogen in a 2:1 ratio) from a compound to form a new compound. An instance is the dehydration of propanol to propene over hot pumice: C3H7|}~&}3CH:CH2 + H2O.

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Deionization It is the elimination of ions from a solution. The typical method is to use an ion-exchange resin. The term is usually applied to the purification of tap water; deionized water is inexpensive to produce in comparison to the distilled water and is passable for several applications.

Deliquescent

Figure 37. Dryer deliquescent. Source: Image by Wikimedia .

It is describing a solid compound that absorbs water from the atmosphere, ultimately forming a solution.

Delocalization It is a spreading out of bonding electrons in a molecule over the molecule.

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Delocalized Bond It is a type of bonding in molecules that arises in addition to sigma bonding. The electrons forming the delocalized bond are not restricted between two atoms; i.e., the electron density of the delocalized electrons is extended over numerous atoms and may extend over the whole molecule. The electron density of the delocalized bond is extended by means of a delocalized molecular orbital and may be observed as a series of pi bonds extending over numerous atoms, for instance the C–O pi bonds in the carboxylate ion and pi bonds in butadiene.

Denaturation

Figure 38. Protein denaturation. Source: Image by Wikimedia.

It is the transition in structure that arises when a protein is heated. These changes are permanent and affect protein’s properties.

Denatured Alcohol It is an alcohol (ethanol) that has been contaminated by the accumulation of small amounts of substances to make it unfit for drinking. Ethanol treated in

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this way may still be useful for several objectives (e.g., as a solvent) but not have taxes or restrictions on its sale.

Depression of Freezing Point It is a colligative property of solutions in which the freezing point of a given solvent is lessened by the existence of a solute. The extent of the reduction is proportional to the molal concentration of the solute. The depression varies only on the concentration and is liberated from solute composition. The proportionality constant, Kf, is known by the name freezing point                 ¦  ^&%  ¦ is the lowering of the temperature and CM is the molal concentration; the unit of Kf is kelvin kilogram mole–1 (K kg mol–1). Although narrowly allied to the property of boiling-point elevation, the cryogenic method can be applicable to measurement of relative molecular mass with substantial precision. A known weight of pure solvent is gradually frozen, with stirring, in an appropriate cold bath and the freezing temperature measured with the help of a Beckmann thermometer.

Derivative It is a compound that could be created from another compound by chemical reaction. Normally, the term is applied to a compound that has a structural resemblance to the parent compound; for instance, chlorobenzene (C6H$Cl) is a derivative of benzene (C6H6).

Derived Unit A unit defined in terms of base units, and not unswervingly from a standard value of the quantity it measures. For instance, the newton is a unit of force expressed as a kilogram meter second–2 (kg m s–2).

Desiccator It is a piece of laboratory apparatus that is used for drying solids or for keeping solids free of moisture. Normally, a desiccator is an air-tight container in which a hygroscopic material (e.g., silica gel or calcium chloride) is being kept to absorb moisture from the atmosphere.

Destructive Distillation It is the process of heating an organic substance   %  that it partially or wholly decomposes to yield volatile products, which are

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successively condensed. The destructive distillation of coal was the process for manufacturing coal tar or coal gas. At one time, methanol was made by the destructive distillation of wood.

Detergent Any of a group of substances that advance the cleansing action of solvents, specifically water. The majority of detergents, comprising SOAP, have the same basic structure. Their molecules have a hydrocarbon chain (tail) that does not entice water molecules. The tail is believed to be hydrophobic (water hating). Attached to this tail is a small group (head) that eagerly ionizes and entices water molecules. It is said to be hydrophilic (water loving). Detergents lessen the surface tension of water and thus advance its wetting power. Since the detergent ions have their hydrophilic heads anchored in the water and their hydrophobic tails protruding above it, the water surface is broken up, allowing the water to spread over the material to be wiped and penetrate between the dirt and material. With the aid of   %  ˆ   The hydrophobic tails of the detergent molecules ‘dissolve’ in oils and grease. The protruding hydrophilic heads repel each other triggering the oil       %  ˆ         More newly synthetic detergents, usually originated from petrochemicals, have been developed. Unlike soaps these detergents do not form insoluble scums with hard water.

Deuterated Compound It is a compound in which one or more that 1H atoms have been substituted by deuterium (2H) atoms.

Deuterium

Figure 39. Deuterium. Source: Image by Pixabay.

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It is a naturally arising stable isotope of hydrogen in which the nucleus comprises one proton and one neutron. The atomic mass is thus roughly twice that of 1H; deuterium is believed to be the ‘heavy hydrogen.’ Chemically it behaves almost identically to hydrogen, making analogous compounds, although reactions of deuterium compounds are usually slower in comparison to those of the corresponding 1H compounds. This is made use of in kinetic studies where the rate of a reaction may be contingent upon the transfer of a hydrogen atom.

Dextrose It is the dextrorotatory naturally arising form of glucose, D-(+)-glucose. Because other stereochemical forms of glucose have no consequence in biological systems the term ‘glucose’ is generally used interchangeably with ‘dextrose’ in biology.

Diazonium Compound

Figure 40. Diazonium compound. Source: Image by Wikipedia.

A compound of the sort ArN2 +X–, where X– a negative ion, and Ar is an aromatic group. Diazonium salts are made by diazotization. They can be isolated but are very unstable, and are typically prepared in solution. The – N2 + group renders the benzene ring vulnerable to nucleophilic substitution (rather than electrophilic substitution).

Diazotization It is the response of an aromatic amine (e.g., aniline) with nitrous acid at low  5 $Z&=&6H$NH2 + HNO2~&6H$N+N + OH– + H2O. The acid is arranged in situ by reaction between sodium nitrite and nitric acid. The resulting diazonium ion is vulnerable to attack by nucleophiles and offers a method of nucleophilic substitution onto the benzene ring.

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Figure 41. Diazotization mechanism. Source: Image by Wikimedia.

Dibasic Acid It is an acid that has two basically acidic hydrogen atoms, such as sulfuric acid. Dibasic acids can give growth to two series of salts. For instance, sulfuric acid (H2SO4) forms hydrogen sulfates (HSO4–), and sulfates (SO42–).

Diffusion

Figure 42. Diffusion in a liquid. Source: Image by Wikimedia.

It is the movement of a gas, solid or liquid, as an outcome of the random thermal motion of its particles (molecules or atoms). A drop of ink in water, for instance, will gradually spread throughout the liquid. Diffusion in solids arises very gently at usual temperatures.

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Dimer A compound (or molecule) created by association or combination of two molecules of a monomer. Cyclopentadiene, for instance, exists as a dimer at room temperature. On heating it dissociates.

Dimethylbenzene An organic hydrocarbon that is prevalent in the light-oil fraction of crude oil. It is used broadly as a solvent. There are three isomeric compounds with this formula and name, distinguished as 1,2-, 1,3-, and 1,4-dimethylbenzene in relation to the positions of the methyl groups on the benzene ring.

Dinucleotide It is a compound of two nucleotides that are associated by their phosphate groups. Imperative instances are the coenzymes FAD and NAD.

Dioxin

Figure 43. Dioxins and dioxin-like compounds. Source: Image by Wikipedia.

It is any of an associated group of highly toxic chlorinated compounds. & ˆ          2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)        \         %‰%$\% and may subsequently arise as an impurity in some types of weedkillers. The defoliant known as AGENT ORANGE used in Vietnam comprised enormous amounts of TCDD. Dioxins cause birth defects and skin disease (chloracne). Dioxins have been liberated into the atmosphere as a result of

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explosions at herbicide manufacturing plants, most remarkably at Seveso, Italy, in 1976.

Dipole A system in which two equal and opposite electric charges are detached by a determinate distance. Polar molecules have permanent dipoles. Induced dipoles can also arise.

Dipole Moment

Figure 44. Magnetic dipole moment. Source: Image by Wikimedia.

It is a quantitative measure of polarity in either a bond (bond moment) or a molecule as a whole (molecular dipole moment). The unit is the debye (equivalent to 3.34 × 10–30 coulomb meters). Molecules such as HF, NH3, H2O, and C6H$NH2 possess dipole moments; CCl4, C6H6, N2, and PF$ do not. The molecular dipole moment can be projected by vector addition of individual bond moments if the bond angles are renowned. The possession of a dipole moment opens the pathways for direct interaction with electric             

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Direct Dyes A group of dyes that are typically azo-compounds derived from benzidene or benzidene derivatives. They are mainly used to dye viscose rayon, cotton, and other cellulose fibers directly, using a neutral bath comprising sodium sulfate or sodium chloride as a mordant.

Disperse Dyes

Figure 45. Disperse dyes. Source: Image by Wikipedia.

`  \ %  %   %  applicable to acetate rayon fabrics. The dye, along with a dispersing agent, is     ‰$Y$/Z&    ‚         %       The orange/ yellow shades are nitroaryl amine derivatives and the green to bluish shades are derivatives of 1-amino anthraquinone.

Displacement Pump It is a commonly used device that is used for conveyance of liquids and gases around chemical plants. It works on the principle of the bicycle pump: a piston elevates the pressure of the fluid and, when it is high enough, a valve opens and the fluid is discharged through an outlet pipe. As the piston moves back the cycle continues and the pressure falls. Displacement pumps can be used to produce extreme high pressures but because of the system of valves, they are more pricey in comparison to other sorts of pump.

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Disproportionation A chemical reaction in which there is instantaneous oxidation and reduction of the same compound. The cannizzarro reaction is an instance in organic chemistry.

Distillation

Figure 46. Distillation process. Source: Image by Pixabay.

It is the process of boiling a liquid and condensing the vapor. Distillation can be used to purify liquids or to distinct components of a liquid mixture.

DNA (Deoxyribonucleic Acid) It is a nucleic acid that is usually found in the chromosomes, which comprises the hereditary information of organisms. The molecule is made up of two antiparallel helical polynucleotide chains coiled around each other to give a double helix. It is also recognized as the Watson-Crick model after Francis &{ § ¥       #“$"

Dopamine It is a catecholamine precursor of norepinephrine and epinephrine. In mammals it is found in the highest proportion in the corpus striatum of the brain, where it functions as an inhibitory neurotransmitter. High levels of dopamine are allied with Parkinson’s disease in humans.

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Figure 47. Dopamine. Source: Image by Wikipedia.

Double Bond A covalent bond between two atoms that comprises two pairs of electrons, one pair being the single bond equivalent (the sigma pair) and the other forming     %  5¨ =`    two lines, for instance H2C=O.

Double Salt When corresponding quantities of certain salts are mixed in aqueous solution and the solution evaporated, a salt may form, for instance; FeSO4. (NH4)2SO4.6H2O. In aqueous solution the salt may behave as a mixture of the two individuals. These salts are known by the name double salts to differentiate them from complex salts, which produce complex ions in solution.

Dryers Devices used in chemical processes to eliminate a liquid from a solid by evaporation. Drying equipment is categorized by the method of conveying heat to a wet solid. This can be by direct contact between the solid (direct dryers) and hot gases, heat transfer by conduction through a retaining metallic wall (indirect dryers), or through infrared rays (infrared dryers).

Drying Oil It is a natural oil, such as linseed oil, that toughens in air. Such oils comprise unsaturated fatty acids that polymerize on oxidation.

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Dye It is basically a coloring material for fabric, leather, etc. Most dyes are now synthetic organic compounds (the first such was the dye mauve synthesized     #ž$Ž  ¥  {= ƒ       organic compounds comprising conjugated double bonds – the bond system accountable for the color is called the chromophore.

Dynamite It is a high explosive that is created by absorbing nitroglycerine into an earthy material such as diatomite (kieselguhr). Solid sticks of dynamite are much safer to hold in comparison to the highly sensitive liquid nitroglycerine.

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E    It is the process in which a crystalline hydrated solid instinctively loses water of crystallization to the air. A powdery deposit is formed gradually.

Elastin

Figure 48. Elastin bovine. Source: Image by Wikipedia.

A structural protein that is prevalent in mammalian connective tissues,        ©        ]  % valine, and alanine are the other main residues.

Electrochemical Equivalent The mass of an element discharged from a solution of its ion when a current of one ampere streams for one second during electrolysis.

Electrochemistry It refers to the study of the formation and behavior of ions in solutions. It comprises electrolysis and the production of electricity by chemical reactions in cells.

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Figure 49. Electrochemistry. Source: Image by Wikimedia.

Electrode It is any part of an electrical device or system that collects or emits electrons or other charge carriers. An electrode may also be used to deflect charged particles by the activities of the electrostatic field that it produces.

Electrode Potential It is a measure of the tendency of an element to make ions in solution. For instance, a metal in a solution involving M+ ions may dissolve in the solution as M+ ions; the metal then has an excess of electrons and the solution an extra of positive ions – thus, the metal becomes negative with respect to the solution. Otherwise, the positive ions may advance electrons from the metal and be deposited as metal atoms. In this case, the metal becomes charged positively in relation to the solution. In either case, a potential distinction is developed between solution and solid, and an equilibrium state will be attained at which further reaction is barred. The equilibrium value of this possible alteration would give a sign of the propensity to form aqueous ions.

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Electrolyte It is a liquid comprising positive and negative ions that conducts electricity by the flow of those charges. Electrolytes can be solutions of acids or metal salts (‘ionic compounds’), generally in water. Instead, they may be molten ionic compounds – again the ions can move easily through the substance. Liquid metals (in which conduction is by free electrons in comparison to ions) are not categorized as electrolytes.

Electromagnetic Radiation It is an energy propagated by magnetic fields and vibrating electric. Electromagnetic radiation forms a whole electromagnetic spectrum, contingent on frequency and varying from high frequency radio waves to low-frequency gamma rays. Electromagnetic radiation can be believed to be as waves (electromagnetic waves) or as streams of photons. The wavelength and frequency are related by: > = c.

    The energy is freed when an atom (or group or molecule) gains an electron in the gas phase to form a negative ion. It is thus the energy of: A + e– ~Y  > >   5    > =       given out. Usually, the molar enthalpy is given for this process of electron   5¦}=}  ª  5§ Y#=% %  typical convention, a negative value suggests that energy is discharged.

       These are compounds in which the number of electrons accessible for bonding is inadequate for the bonds to comprise traditional two-electron covalent bonds. Diborane, B2H6, is an instance in which each boron atom has two terminal hydrogen atoms bound by traditional electron-pair bonds and in addition the molecule has two hydrogen atoms bridging the boron atoms (B–H–B). In each bond there are only two electrons for the bonding orbital.

Electron Diffraction It is a technique that is used to define the structure of substances, mainly the shapes of molecules in the gaseous phase. A beam of electrons focused through a gas at low pressure yields a series of concentric rings on a photographic

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plate. The dimensions of these rings are allied to the interatomic distances in the molecules.

Electronegative It is describing a molecule or atom that attracts electrons, creating negative ions. Instances of electronegative elements comprise the halogens (chlorine etc.), which willingly form negative ions (F–, Cl–, etc.).

Electronegativity Electronegativity is a measure of the propensity of an atom in a molecule to entice electrons to itself. Elements to the right-hand side of the periodic table     > 5>    $   ‰=]      \       >5/žY#$=       known by the name electropositive elements. Distinctive electronegativities of atoms in the identical molecule give rise to polar bonds and occasionally to polar molecules. As the concept of electronegativity is not exactly stated it cannot be measured precisely and several electronegativity scales exist. Although the actual values contrast, the scales are in good comparative agreement.

Electron Spin Resonance (ESR) It is an identical technique to nuclear magnetic resonance, but applicable to unpaired electrons in a molecule (rather than to the nuclei). It is considered as a powerful method of studying free radicals. ESR is also used in inorganic chemistry to study transition-metal complexes.

Electron-Transport Chain It is a chain of chemical reactions comprising enzymes and proteins, resulting in the creation of ATP and the transfer of hydrogen atoms to oxygen to form water. The enzymes and other proteins are, in eukaryotic cells, positioned in the inner membrane of the mitochondria and are gathered into discrete complexes. The abridged coenzyme NADH gives up two electrons to the first component in the chain, NADH dehydrogenase, and two hydrogen ions (H+) are freed from the matrix of the mitochondria into the intermembrane space. The electrons are conveyed along the chain to a carrier molecule (ubiquinone). Ubiquinone passes them to the next intricate that comprises

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cytochromes b and c1. Another carrier (cytochrome c) conveys the electrons     ?        [    oxidase to lessen an oxygen atom that combines with two H+ ions to form water.

Electronvolt A unit of energy equal to 1.6021917 × 10–19 joule. It is described as the energy needed to move an electron charge across a possible difference of one volt. It has been used to measure the kinetic energies of ions or elementary particles, or the ionization potentials of molecules.

Electrophile It is an electron-deficient molecule or ion that takes part in an organic reaction. The electrophile can be either a positive ion (H+, NO2+), a molecule that can admit an electron pair (SO3, O3), or an electron-deficient group (e.g., a carbene). The electrophile attacks negatively charged areas of molecules that normally arise from the existence in the molecule of a polar or group bond or single or of pi-bonds.

Electrophilic Addition It is a reaction comprising the accumulation of a small molecule to an unsaturated organic compound, across the atoms combined by a double or triple bond with an electrophile as the initial attacking species. The reaction is commenced by the attack of the electrophile on the electron rich area of the molecule. The mechanism of electrophilic accumulation is thought to be ionic, as in the addition of HBr to ethene.

Electrophilic Substitution It is a reaction comprising substitution of an atom or group of atoms in an organic compound with an electrophile as the attacking substituent. Electrophilic substitution is extremely common in aromatic compounds, in which electrophiles are swapped onto the ring. An instance is the nitration of benzene: C6H6 + NO2+~&6H$NO2 + H+ The nitrenium ion (NO2+) is formed by mixing sulfuric acids and concentrated nitric: HNO3 + H2SO4~}2NO3+ + HSO4– H2NO3+~Œ|2+ + H2O.

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Electrophoresis It is the use of an electric field (formed between two electrodes) to cause charged particles of a colloid to move through a solution. The technique is used to distinct and recognize colloidal substances such as proteins, carbohydrates, and nucleic acids. Several experimental arrangements are used. One simple technique uses a strip of adsorbent paper soaked in a buffer solution with electrodes placed at two points on the paper. This technique is sometimes known by the name electrochromatography. In gel electrophoresis, used to separate DNA fragments, the medium is a layer of gel.

Electrovalent Bond A binding force between the ions in compounds in which the ions are created by complete convey of electrons from one element to another element or radical. For instance, Na + Cl become Na+ + Cl–. The electrovalent bond ascends from the excess of the net attractive force between the ions of opposite charge over the net repulsive force between ions of similar charge. It is generally seen that the magnitude of electrovalent interactions is of the order 102–103 kJ mol–1 and electrovalent compounds are normally solids with rigid lattices of closely packed ions.

Element Element is a substance that cannot be decomposed chemically into more simple substances. It is usually seen that the atoms of an element all have the similar proton number (and thus the same number of electrons, which governs the chemical activity). At present there are almost 114 reported chemical elements, although research is ongoing all the time to synthesize new ones. The elements from hydrogen (p.n. 1) to uranium (92) all occur logically, with the exclusion of technetium (43) that is produced unnaturally by particle bombardment. Technetium and elements with proton numbers higher than 84 (polonium) are radioactive.

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Elevation of Boiling Point

Figure 50. Elevation of boiling point. Source: Image by Wikipedia.

A colligative property of solutions in which the boiling point of a solution is elevated comparative to that of the pure solvent. The elevation is unswervingly proportional to the number of solute molecules introduced                      proportionality constant, kB, is known by the name boiling-point elevation constant or occasionally the ebulioscopic constant.

Elimination Reaction It is a reaction comprising the eradication of a small molecule, e.g., hydrogen or water chloride, from an organic molecule to give an unsaturated compound. An instance is the removal of a water molecule from an alcohol to make an alkene. An elimination reaction is usually in competition with a substitution reaction and the predominant product will be contingent upon the reaction conditions. The reaction of bromoethane with sodium hydroxide could produce either ethanol (by substitution of the Br with OH) or ethene (by elimination of HBr). The earlier product predominates if the reaction is carried out in an alcoholic solution and the final if the solution is aqueous.

Elution The elimination of an adsorbed substance in a chromatography column or ion-exchange column with the help of a solvent (eluent), giving a solution

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called the eluate. The chromatography column can selectively adsorb one or more than one component from the mixture. In order to make sure the efficient recovery of these components, graded elution is used. The eluent is altered in a steady manner starting with a nonpolar solvent and slowly replacing it by a more polar one. This will wash the strongly polar components from the column.

Emulsion It is a colloid in which a liquid phase (small droplets with a diameter range 10Y$–10–7 cm) is disseminated or suspended in a liquid medium. Emulsions are categorized as lyophobic (solvent-repelling and usually unbalanced) or lyophilic (solvent attracting and usually stable).

Enantiomer (Enantiomorph) This is a compound whose structure is not superimposable on its mirror image; one of any pair of optical isomers.

Endorphin One of a group of peptides formed in the brain and other tissues that are freed after injury and have pain-relieving effects akin to those of opiate alkaloids, such as morphine. They comprise the enkephalins that comprise just five amino acids. Other larger endorphins arise in the pituitary, while some are polypeptides, found largely in adrenal gland, pancreas, and other tissues.

Endothermic It is basically describing a process in which heat is absorbed (i.e., heat flows from outside the system, or the temperature tumbles). The dissolving of a salt in water, for example, is usually an endothermic process.

Energy It is a property of a system; a measure of its capability to do work. Energy and work have the identical unit: the joule (J). It is suitable to split energy into potential energy (‘stored’ energy) and kinetic energy (energy of motion). Names are given to several distinctive forms of energy (electrical, chemical, nuclear, etc.); the only real distinction lies in the system under discussion. For instance, chemical energy is the kinetic and potential energies of electrons in a chemical compound.

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Energy Level It is one of the discrete energies that an atom, molecule, ion, etc., can be in accordance with quantum theory. Thus, in an atom there are some definite orbits that the electrons can be in, corresponding to definite electronic energy levels of the atom. Likewise, a vibrating or rotating molecule can have separate vibrational and rotational energy levels.

    It is a diagram that traces the transition in the energy of a system throughout the course of a reaction. Energy profiles are attained by plotting the possible energy of the reacting particles against the reaction coordinate. To attain the reaction, coordinate the energy of the entire interacting system is plotted against position for the molecules. The reaction coordinate is the route for which the energy is a minimum.

Enzyme

Figure 51. Enzyme action. Source: Image by Wikipedia.

It is basically a macromolecule that catalyzes biochemical reactions. Enzymes act with a given compound (the substrate) to produce a multifaceted, which then forms the products of the reaction. The enzyme itself is unaffected in the reaction; its existence permits the occurrence of reaction. The names of most enzymes end in -ase, added to the substrate (e.g., lactase) or the reaction (e.g., hydrogenase).

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Enzyme Technology It is believed to be the branch of biotechnology that exploits enzymes for industrial purposes. For instance, rennet (impure rennin) is produced on a large scale to make junkets and cheese. Enzymes are also used to resolve the concentration of reactants or products in explicit reactions catalyzed by them.

Epimerism A form of isomerism shown by carbohydrates in which the isomers (epimers) >         Y|}          between degrees Celsius (C) and degrees Fahrenheit (F) the given formula is &J$5 Y"=J“`  © ƒ    5#ŽžŽY#!"Ž=% a German physicist, who in the year 1714, suggested a scale of this type.

Faraday A section of electric charge equivalent to the charge needed to emit one mole

     \  >      “Ž‰ž$" coulombs. The unit was named after Michael Faraday (1791– 1867) who was a British chemist and physicist.

Fehling’s Solution It is a solution that is used to test for the aldehyde group (–CHO). It is made freshly and is a mixture of copper (II) sulfate solution along with alkaline potassium sodium 2,3-dihydroxybutanedioate (tartrate). While heating the aldehyde, the mixture becomes oxidized into a carboxylic acid, and with it a red precipitate of copper(I) oxide and copper metal is generated. The tartrate is available to complex with the copper (II) ions that is original in order to prevent precipitation of copper (II) hydroxide. It is named after the German chemist H. C. (Hermann von Fehling).

Fermentation A chemical reaction that is produced by the means of microorganisms (molds, bacteria, or yeasts) and the most usual example is the construction of ethanol that comes from sugars: C6H12O6~&2H$OH + 2CO2

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Ferredoxins It is a cluster of red-brown proteins which has emerged in green plants, most of the bacteria and specific animal tissues. They carry nonheme iron in connection with sulfur which is present at the active site. They act as a hefty reducing agent (that is, very negative redox potentials) and play a major role as the carriers of electrons, for instance in photosynthesis and nitrogen fixation. They have also been detached from mitochondria.

Ferrocene Ferrocene refers to an orange crystalline solid. It is a classic example of a sandwich compound, whereby an iron (II) ion is interrelated to two cyclopentadienyl ions. The bonding incorporates overlap of d orbitals present on the iron with the pi electrons which are in the cyclopentadienyl ring. The compound can experience substitution reactions which can take place on the rings, which possess an aromatic character. The systematic  {  \¨\   5``=

Filler Filler is a solid material which is implemented to modify the physical properties or lessen the value of synthetic compounds, for example rubbers, plastics, resins and paints. More such compounds that are used as fillers are Slate powder, glass fiber, mica, and cotton.

Filter Pump

Figure 52. Filter pump. Source: Image by Flickr.

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Refers to a type of vacuum pump in which a jet of water is passed through a nozzle forcefully which contains air molecules out of the system. Filter pumps are incapable of producing pressures lower than the vapor pressure of water. They are implemented in the laboratory for carrying out >   %  %      _ a low-grade vacuum.

Filtration The process of withdrawing dangled particles from a fluid by carrying out or forcing the fluid by means of a porous material (the filter). The fluid that goes through the filter is called the filtrate. In laboratory filtration, the use of filter paper or sintered glass is usually done.

Fine Organic Chemicals Carbon compounds, for example dyes and drugs, are constructed only in little quantities. Their major requirement is that they must possess an   %       “$”  are produced for special purposes, for instance, for use in spectroscopy, pharmacology, as well as in electronics.

Fine Structure Fine structure is firmly spaced lines which emerge at high resolution and take place in a spectral line or band. Fine structure may be an outcome of either the vibration of the molecules or by the electron spin. Hyperfine structure that appears at very high resolution is the result of the atomic nucleus impacting the plausible energy levels of the atom.

First-Order Reaction Refers to the reaction in which the rate of reaction is in proportion to the concentration of one of the or separate reacting substances. In the reacting substance the concentration is increased to the power one; that is rate = k[A]. For instance, the decomposition of hydrogen peroxide refers to a firstorder reaction; that is rate = k[H2O2].

Fischer–Tropsch Process A technique of constructing a mixture of hydrocarbons by making the use of hydrogen as well as carbon monoxide (2:1 ratio) crossing over catalysts

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{{       //Z& ?%      alcohols and carbonyl compounds, can be purified in order to make fuels that is further used in diesel and gasoline engines. For the same reason it was implemented by Germany during World War II. In recent years, the process is one way of making SNG.

Flare Stack It is a chimney at the apex of which gases that are not useful are burnt either in an oil refinery or in other chemical plants.

Flash Photolysis A method for exploring free radicals in gases and the gas is kept at low pressure in a long glass or quartz tube, and an immersion spectrum taken by making the use of a beam of light which goes down the tube. The gas is put through a very brief exceptional flash of light out of a lamp present outside the tube, generating free radicals, which are demonstrated by their spectra. Measurements of the magnitude of spectral lines can be done with time by employing an oscilloscope, and the kinetics of very reactions that are very fast and can therefore be investigated.

Flash Point The lowest temperature at which adequate vapor is radiated by a flammable liquid to erupt in the existence of a spark.

Flavanone It is refers to a type of flavonoid. Flavanone glycosides are established in flowering plants.

Flavonoid

Figure 53. Flavonoid. Source: Image by Wikipedia.

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One of a common group of plant compounds containing the C6–C3– C6 chemical skeleton that includes C6 which is a benzene ring. They are a     \        They are categorized according to the C3 portion and incorporates the          ]    > ˆ >     ˆ >     ]  %%        ]     ˆ > %  % and leukoanthocyanidins, are the examples of water soluble and mostly found in the cell vacuole.

Flavoprotein Refers to a protein which is joined together in which a flavin (FAD or FMN) is connected to a protein component. The enzymes called the Flavoproteins are found in the electron-transport chain.

Flocculation Refers to the amalgamation of the particles of a finely split up precipitates, for example, a colloid, into greater particles or clumps that are submerged and can be effortlessly filtered off.

Fluidization It is the suspension of a finely dissected solid in a liquid or gas which is upward-flowing. This suspension imitates various properties of liquids, like enabling objects to ‘float’ in it. Fluidized beds so formulated are essential in the chemical industry.

Fluorescein It is a fluorescent dye which is applied as an absorption indicator. It contains a yellow solution along with green fluorescence.

Fluorescence The absorption of energy done by atoms, molecules, etc., subsequently by rapid emission of electromagnetic radiation to such an extent that the particles make changes so as to lower energy states. See phosphorescence.

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Fluorine It is a little greenish-yellow extremely reactive gaseous element which belongs to the halogens (group 17 of the periodic table, formerly VIIA). It takes place remarkably as fluorite (CaF2) and cryolite (Na3AlF3) but its traces are also extensively dispensed with various other minerals. It is a little         %     //Ž$”  the crust of the Earth. The excessive reactivity of the element detains its isolation. Fluorine in recent times is constructed through electrolysis of molten KF/HF electrolytes, by applying copper or steel apparatus. Its preparation by traditional chemical techniques is not possible. Fluorine is greatly electronegative and demonstrates a strong electron extracting effect present on adjacent bonds therefore CF3COOH is a powerful acid (while CH3COOH is not).      ˆ       only be applied in apparatus which are purpose-built; gloves and face covers    [       ˆ      exposure must be managed as a hospital emergency.

Fluorocarbon

Figure 54. Fluorocarbon. Source: Image by Wikipedia.

               ˆ    rather than hydrogen atoms. Fluorocarbons are unreactive and nearly all are stable up to extreme temperatures. They can be used in various places,

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for example, in aerosol propellants, oils as well as greases and synthetic polymers for example PTFE.

Fluxional Molecule A molecule in which the essential atoms transform their relative positions so randomly at room temperature that the general notion of structure is insufficient; that is no particular structure lives for a prolonged period for about 10–2 seconds and the comparative positions become identical. For instance, ClF3  YŽ/Z&    \ ’'     

 temperature the fluorine atoms are demonstrated as moving quickly over the surface of the chlorine atom in a phase of exchange and are efficiently indistinguishable.

Foam It is a diffusion of bubbles of gas in a liquid, commonly balanced by a Surfactant. Solid foams, for example enlarged polystyrene or foam rubber, are constructed by permitting liquid foams to set.

Folic Acid It is one of the water-soluble B-groups of vitamins. The prime nutritional sources of folic acid are leafy vegetables, liver, broccoli and kidney. Insufficiency of the vitamin displays itself in anemia in a similar way to vitamin B12 deficiency, while insufficiency at the time pregnancy escalated the risk of birth deficiencies in children. Folic acid is crucial in metabolism in different coenzyme forms, all of which are particularly concerned with the shift and use of the single carbon (C1) group. Prior to functioning in this way folic acid must be lessened to either dihydrofolic acid (FH2) or tetrahydrofolic acid (FH4). It is essential when it comes to the growth and reproduction of cells, taking part in the synthesis of purines and thymine.

Fossil Fuel It is a mineral fuel that takes the form underground from the remnants of living organisms. Fossil fuels incorporate coal, natural gas, petroleum and peat.

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Figure 55. Industry fossil fuel oil. Source: Image by Pixabay.

Fraction This refers to a mixture of liquids with identical boiling points gathered by fractional distillation.

Fractional Crystallization It is the crystallization of one constituent from a mixture in solution. When two or more materials are available either in a liquid or in solution, on cooling to a reduced temperature one substance will favorably construct crystals, leaving the other substance in the liquid (or submerged) state. Fractional crystallization can therefore be applied so as to purify or differentiate substances if the accurate conditions are known. Fractional distillation (fractionation) is distillation occurs with partial reflux, by implementing a long vertical column which is known as the fractionating column.

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It makes use of the fact that the vapor state above a liquid mixture is commonly richer when it comes to the more volatile component. If the     ˆ?  {    _   %        the complete dissociation of two or more volatile liquids. Fractionation is the basic process for constructing petroleum from crude oil. Dissimilar to   ˆ?%            loss, and exceptional designs are implemented to expand the liquid-vapor interface.

Free Energy It is an evaluation of the ability of a system to carry out useful and essential work. See Gibbs function; Helmholtz function.

Free Radical It is an atom or group of atoms having a single unpaired electron. Free radicals are generated by diffusing a covalent bond; for instance: CH3&~ CH3š&š      \  Œ  all the free radicals are highly reactive and can be balanced and isolated only under exceptional conditions. They can be analyzed by electron spin resonance.

Freezing Mixtures Two or more substances assorted together in order to construct a low temperature. The most common example for this is a mixture of sodium     5Y/Z&=

Freezing Point

Figure 56. Freezing and boiling point.

Source: Image by Wikipedia.

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Refers to the temperature at which a liquid is in the state of equilibrium with its solid state at standard pressure and lower to which the liquid freezes

     {  _  quantitatively equal to the melting point of the solid.

Friedel–Crafts Reaction It is a class of reaction in which an alkyl or acyl group is exchanged on a benzene ring. In Friedel– Crafts alkylation the reactant is a haloalkane, and an alkylbenzene is manufactured: CH3Cl + C6H6~&6H$CH3 + HCl. When it comes to the Friedel–Crafts acylation the reactant is an acyl halide and the end result is an aromatic ketone: CH3COCl + C6H6~&6H$COCH3 + HCl.     {    #//Z&     as a catalyst. This receives a lone pair of electrons from the halogen atom present on the haloalkane or acyl halide, which gives a positive charge on the associated carbon atom as an outcome. The reaction then becomes electrophilic substitution. It is also attainable to make the use of alkenes (for alkylation) and acid anhydrides (for acylation). It is named after Charles Friedel (1832– 99) who was a French chemist and the US chemist James Crafts (1832–99).

Fructose

Figure 57. Fructose. Source: Image by Wikipedia.

It is a sugar which emerges in fruit juices, honey, as well as cane sugar. It is a ketohexose, living in a pyranose state when free. In amalgamation (for example, in sucrose) it lives in the furanose form.

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Fucoxanthin It is a xanthophyll pigment of diatoms, brown algae, along with the golden-brown algae. The light which is captivated is applied with extreme efficiency in photosynthesis, the energy first being shifted to chlorophyll a. It contains three absorption peaks shielding the blue and green segments of the spectrum.

Fuel Cell It is a type of cell in which fuel is transformed into electricity, directly. In one form, hydrogen gas and oxygen gas are sustained to the surfaces of two porous nickel electrodes submerged in the solution of potassium hydroxide. The oxygen reacts to form hydroxyl (OH–) ions, which it breaks into the solution, leaving the electrode with a positive charge. The hydrogen becomes responsive with the OH– ions in the solution in order to form water, abjuring electrons to leave a negative charge on the other electrode. Large fuel cells can produce tens of amperes. Generally, the E.M.F. is approximately 0.9 volt   Ž/”

Fundamental Units The units of length, mass, in addition to time that constructs the foundation of most systems of units. In SI, the basic units are the meter, the kilogram, and the second.

Furan It is heterocyclic liquid organic compounds. Its five-membered ring has four carbon atoms along with one oxygen atom. The structure is the attribute of some monosaccharide sugars (furanoses).

Fusel Oil It is a mixture of alcohols having high-molecular weight in addition to some esters and fatty acids, constructed from alcoholic fermentation and acquired during distillation. It is applied as a source of higher alcohols.

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G Galactose It is a sugar which is located in lactose and a lot of polysaccharides. It becomes aldohexose, isomeric along with glucose.

Gas Refers to the state of matter where the forces of attraction in between the particles of a substance are minute. The particles are free to move and gases and have no proper shape or volume. The atoms or molecules of a gas are in a constant recurrent state of motion and are constantly colliding with each other together with the walls of the containing vessel. These collisions or crashing with the walls construct the pressure of a gas.

Gas Chromatography A type of chromatography extensively applied for the separation and analysis of mixtures. Gas chromatography appoints a column loaded with either a solid stationary state (gas–solid chromatography or GSC) or a solid covered with a nonvolatile liquid (gas–liquid chromatography or GLC). The whole column is set down in a thermostatically regulated heating jacket. A volatile sample is instituted into the column by implementing a syringe, and a carrier gas, for example, hydrogen or nitrogen, is progressed through it.           ˆ?  Some of the constituents will cling more rapidly to the stationary state as compared to others, either due to the fact that they become associated with the surface of the solid or because they disintegrate in the liquid. The time taken for various components to move across the column is characteristic of         [

Gas Laws Laws associated with the temperature, pressure, as well as volume of a fixed mass of gas. The prominent gas laws are Boyle’s Law and Charles’ Law. The laws are not accepted precisely by any real gas, but many usual gases accept them under specific conditions, mainly at high temperatures and low pressures. A gas that would accept the laws on top of all pressures and temperatures is said to be ideal or a perfect gas.

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Gasohol An alcohol (ethanol) acquired through the process of industrial fermentation of sugar for its use as a motor fuel. In Brazil, it has been constructed on a far-reaching level.

Gas oil One of the main fragments which is acquired from petroleum through distillation, implemented as a fuel for diesel engines.

Gel

Figure 58. Gel. Source: Image by Wikimedia.

A lyophilic colloid that is generally sturdy but might be instigated to partially coagulate under given conditions (for example, reducing the temperature). This generates a pseudo-solid or smoothly deformable jellylike mass, known as a gel, in which convoluting particles circle the whole dispersing medium. These gels at times can be further subdivided into elastic gels (for instance, gelatin) and rigid gels (such as, silica gel).

Gelatin A pale-yellow protein acquired from the bones, hides, and skins of animals. It takes the shape of a colloidal jelly when disintegrated in hot water and is applied in the food industry, for the purpose of making capsules for different

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medicinal drugs, in the form of an adhesive and sizing medium, along with photographic emulsions.

Gel Filtration It is a form of column chromatography where a gel is applied in the form of stationary medium. Constituents pass through pores in the gel at an amount which relies on the dimensions of their molecules. The method is applied to discrete proteins.

Gem Positions Positions on the same atom in a molecule, for instance, 1,1-dichloroethane (CH3CHCl2), in which the two chlorine atoms are on the identical carbon, is a gem dihalide.

Gibberellic Acid

Figure 59. Gibberellic acid. Source: Image by Wikipedia.

           with GA1 and GA2 it was secluded from Gibberella fujikuroi, which is a fungus that is accountable for infecting rice seedlings resulting in their tall growth which is abnormal.

Gibberellin A plant hormone incorporated mainly in shoot extension. Gibberellins are diterpenoids; their molecules contain the gibbane skeleton. More than thirty have been secluded, the first and one of the most usual being gibberellic acid, GA3.

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Gibb’s Function A thermodynamic function explained by G = H – TS where H is the enthalpy, T the thermodynamic temperature, and S refers to the entropy. It is functional for identifying the conditions which are of chemical equilibrium for reactions for continual temperature and pressure (G is a minimum). It is named after Josiah Willard Gibbs (1839–1903) who was a US mathematician and physicist, and was the one who first established the theory and concept of chemical thermodynamics.

Globulin It is one of a group of proteins that are indissoluble in water but will easily dissolve when it comes to neutral solutions of specific salts. They usually contain glycine and solidify when heated. Three categories of globulins   >  

      5     > nonprotein material. † globulins are produced in reticuloendothelial tissues, lymphocytes, and plasma cells and nearly all of them consist of antibody activity.

Glove Box A sealed box having gloves suited to ports on one side and possessing transparent top, applied for either safety reasons or to tackle with materials in a motionless or sterile atmosphere.

Glucose

Figure 60. Glucose. Source: Image by Wikipedia.

It is a monosaccharide which takes place widely in nature in the form of D-glucose. It takes palace as glucose units in sucrose, starch, and cellulose.

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`      { \   \ release systems.

Glue An adhesive of which there are different types of it. Moist solutions of starch and ethyl cellulose are applied as pastes for the purpose of sticking paper; conventional wood glue is produced by boiling animal bones (refer to gelatin); rapid drying adhesives are produced by disintegrating rubber or a synthetic polymer in a volatile solvent; and some polymers, for example, epoxy resins and polyvinyl acetate (PVA), are themselves used in the form of glues.

Glutathione This refers to a tripeptide of cysteine, glutamic acid, and glycine, extensively dispensed in existing tissues. It contributes in most of the oxidation–reduction reactions, because of the reactive thiol group (–SH) being effortlessly oxidized to the disulfide (–S–S–), and performs as an antioxidant, together with a coenzyme to numerous enzymes.

Gluten A mixture of proteins discovered in wheat flour. It mainly consists of two major proteins (gliaden and glutelin), the proteins being available in more or less equal quantities. Most of the people are sensitive to gluten (celiac disease) and it is mandatory for them to have a gluten-free diet.

Glycan A polysaccharide produced of more than 10 monosaccharide residues. A homoglycan is made up of a single type of sugar5%«“$”=   the glycans act both as structural units (for example, cellulose in plants and chitin in invertebrates) as well as energy stores (for example, starch in plants and glycogen in animals). The most usual homoglycans are constructed of D-glucose units which are known as glucans.

Glyceride An ester formulated between glycerol (propane-1,2,3-triol) and either one or additional carboxylic acids. Glycerol contains three alcohol groups, and if all three groups have created esters, the compound becomes a triglyceride.

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Naturally the fats and oils that take place are triglycerides of long-chain carboxylic acids (therefore, the name ‘fatty acid’). The prominent carboxylic acids constructing glycerides in fats and oils are: š š š

octadecanoic acid (stearic acid), which is a saturated acid CH3(CH2)16COOH. hexadecenoic acid (palmitic acid), refers to a saturated acid CH3(CH2)14COOH. cis-9-octadecenoic acid (oleic acid), that is an unsaturated acid. CH3(CH2)7CH:CH(CH2)7COOH.

Glycogen It is a polysaccharide which is the prime and foremost carbohydrate store of animals. It consists of many glucose units associated in the same manner to starch. Glycogen is quickly hydrolyzed in a stepwise way to glucose itself. It is deposited immensely in the liver and in muscle but is discovered extensively distributed in the body.

Glycolipid A sugar which contains lipid with one or more sugar residues associated to a lipid through a glycosidic link (or ester link in prokaryotes). Glycolipids play a major and crucial structural part in cell membranes, in which the sugar remnants are extracellular. Animal glycolipids are obtained from sphingosine, an amino alcohol having a long chain of unsaturated hydrocarbons. In glycolipids, the amino group of sphingosines is connected to a chain of fatty acids by means of an amide bond and the chief group of hydroxyls is associated with a sugar residue. The easiest glycolipid (in animal cells) is called the cerebroside, which possesses one sugar residue (which can be either glucose or galactose). Glycolipids having branched chains of sugar residues are called the gangliosides. Both the chains, that is, the fatty acid chain and sphingosine chain are hydrophobic whereas the sugar remnants are hydrophilic, constructing glycolipids amphiprotic.

Glycolysis This refers to the transformation of glucose into pyruvate, along with the release of some amount of energy which is in the form of ATP. Glycolysis takes place in cell cytoplasm. It capitulate two molecules of ATP and two

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of NADH2 per molecule of glucose. In conditions that are anaerobic, breakdown extends no further and pyruvate is transformed into ethanol or lactic acid for the purpose of storage or elimination. In aerobic conditions, glycolysis is succeeded by the Krebs Cycle. The rate of glycolysis is regulated by the enzyme phosphofructokinase, which is responsible for catalyzing a significant irreversible reaction. There exist two other reactions that are irreversible and are catalyzed through hexokinase and pyruvate kinase.

Glycosaminoglycan (GAG) One of a group of compounds, most of the times called mucopolysaccharides, comprising of long chains that are unbranched and of reiterating disaccharide sugars, one of the two sugar remnants being an amino sugar – either N-acetylglucosamine or N-acetyl galactosamine. These constituents are available in connective tissue; they incorporate heparin and hyaluronic acid. Most glycosaminoglycans are connected to protein in order to form proteoglycans (sometimes called mucoproteins).

Glycoside It is a mixture in which the ring form of a sugar is associated with few of the other organic groups. The link in a glycoside takes place at the anomeric carbon atom. If in case, the hydroxyl group at this carbon is eliminated, then the outcome is a glycosyl group. If this group is connected to another organic group by means of an oxygen atom, then in that case the end product of the compound is an O-glycoside. The linkage ring–O–organic group is a glycosidic link. A simple instance of a glycoside would be the compound constructed by replacing the anomeric –OH group in a sugar through the methoxy group, –OCH3         beta in accordance to whether the organic group is either below or above the ring at the anomeric carbon. If the glycosyl group is connected by means of      %  %Q\ %&\ % etc. Compounds in which the glycosyl group is associated through nitrogen (that is N-glycosides) are also known as glucosamines. If the sugar is called the glucose, the compound is known as glucoside. Glycosides take place in plants and incorporate many functional substances.

Glyoxylate Cycle It is a mitigation of the Krebs cycle taking place in few of the microorganisms, algae, and higher plants in areas where fats are being quickly metabolized,

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for example, in germinating fat-rich seeds. Acetyl groups established from the fatty acids are moved through the glyoxylate cycle, with the eventual construction of largely carbohydrates.

Granulation A process for expanding particles in order to ameliorate the flow attributes of solid reactants and products in the processes of industrial chemicals. The bigger a particle and the freer in a solid from fine materials, the easier it becomes for it to flow. Dry granulation generates pellets from dry materials that are smashed into the desired size. Wet granulation incorporates the inclusion of a liquid to the material, and the paste that is the outcome is released and dried prior to cutting to the desirable size.

Gravimetric Analysis It is a technique of quantitative analysis where the final analytical assessment is made by the process of weighing. There are a lot of differences in the technique but in essence they all comprises of: š š

taking an explicitly weighed representatives into solution; precipitation as a familiar compound through a quantitative reaction; š the procedures of digestion and coagulation; š     ]  š drying and weighing in a form of a pure compound.             _   >    ?      \   

Gray The SI unit of immersed energy dose per unit mass develops from the channel of radiation of ionizing through living tissue. One gray refers to energy absorption of one joule per kilogram of mass. The unit is named after ¬}© 5#“/$YŽ$=%   ‚     

Group In the periodic table, it is a series of chemically identical elements that carry the same electronic configurations. A group is therefore a column of the periodic table. In organic chemistry, an arrangement of atoms that provides

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a particular kind of property on a molecule and allows it to be positioned in a specific class, for example, the aldehyde group –CHO.

GTP (Guanosine Triphosphate) It is a nucleoside triphosphate taking place in all cells in the form of a coenzyme for different prime processes. Most of the time, it bestows energy through undertaking hydrolysis to GDP (guanosine diphosphate) in addition to a phosphate group, a reaction catalyzed by an enzyme or various other components containing GTPase activity. In the synthesis of protein, GTP is important for the gathering of ribosomes and extension of the polypeptide chain. It is also essential and needed for the gathering of microtubules, for the transport of protein enclosed in cells, and for the passing on messages to different components of the cell in signal transduction.

Guanidine It is a vigorously basic crystalline organic compound that can be nitrated in order to make a strong explosive. It is also applied in constructing dyestuffs, medicines as well as the polymer resins.

Guanosine (Guanine Nucleoside) A nucleoside available in DNA and RNA and comprises guanine associated  ƒ\ >  „\  

Gum This refers to one of a group of substances that dilate in water in order to formulate gels or sticky solutions. Identical compounds that make slimy solutions are known as mucilage. Gums and mucilages are not chemically separable. Nearly all are heterosaccharides, which are large, complex, mobile, and sometimes highly-branched molecules.

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H Halocarbon

Figure 61. Halocarbon. Source: Image by Flickr.

This refers to a chemical compound that has carbon atoms chained with halogen atoms and (often) hydrogen atoms. The halocarbons incorporate haloalkanes like tetrachloromethane (CCl4) as well as the haloforms (CHCl3, CHBr3, etc.). There are different types of halocarbons that are                   %      ˆ    5& &= >  %ˆ %      crucial in the form of refrigerants, aerosol propellants, and in constructing rigid plastic foams.

Haloform It is any of the four compounds CHX3, in which X is a halogen atom (F, fluoroform; Cl, chloroform; Br, bromoform; I, iodoform). The methodical names are as follows: trifluoromethane, trichloromethane, tribromomethane, and triiodomethane.

Haloform Reaction Refers to a reaction of a methyl ketone with NaOX, where X is Cl, Br, or I, to provide a haloform along with sodium chlorate(I), for instance: RCOCH3 "Œ |&~€&|&&3 + 3NaOH RCOCl3Œ |}~Œ |&|€&}&3. The reaction can be implemented in order to construct carboxylic acids (from the NaOCOR), and is mainly useful when R is an aromatic group. The reason for this is that the starting ketone, RCOCH3, can be manufactured by Friedel–Crafts acetylation.

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Halogenating Agent A compound applied to bring the halogen atoms into a molecule. Given examples are phosphorus trichloride (PCl3) and aluminum trichloride (AlCl3).

Halogenation Refers to a reaction in which a halogen atom is initiated into a molecule. Halogenations are identified as chlorinations, brominations, fluorinations, etc., in accordance with the element involved. There are various methods. š š š

Direct reaction with the element by making the use of either high temperature or ultraviolet radiation: CH4 + Cl2~&}3Cl + HCl Inclusion to a double bond: H2C:CH2 }&~&2H$Cl Reaction of a hydroxyl group together with a halogenating agent, for example, PCl3: C2H$|}~&2H$Cl + OH–.

Halogens A group of elements (that is, group 17, formerly VIIA, of the periodic table) consisting of fluorine, chlorine, iodine, and bromine in addition to the shortlived radioactive element astatine. Nearly all the halogens consist of outer valence shells that are one electron short of a configuration of rare-gas. Due to this, the halogens are distinguished by high electron accordance and extreme electronegativities, fluorine that is predominantly known as the most electronegative element.

Hammer Mill A tool used in the chemical industry which is used for crushing and grinding materials that are solid and at high speeds to a particular given size. The collision between the particles, grinding plates, and grinding hammers crumbles the particles. Hammer mills can be applied for a large variety of soft material as compared to other types of grinding equipment.

Hardening (of Oils) The transformation of liquid plant oils into a phase which is more solid for use in margarine by hydrogenation using a nickel catalyst. In vegetable oils the fatty acids present (as glycerides) have double bonds (that is, they are unsaturated). The hydrogenation process raises the quantity of unsaturated

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material, expanding the melting point, yet still the unsaturated fatty acids are still left.

Heat Energy shifted as an outcome of a variation in temperature. The term is at times loosely used to refer to internal energy (that is, the average of kinetic and potential energy of the particles). It is usually used in chemistry to elaborate such quantities as heat of combustion, heat of neutralization, etc. These are actually called the molar enthalpies for the transformation,  >     ¦}­          circumstances, while the subscript M denotes that the enthalpy transition is carried out for one mole. The unit is most commonly the kilojoule per  5{§ Y#=‚    %¦} >  ?   reaction.

Heat Exchanger It is a tool that permits the heat from a hot fluid to be shifted into a cool fluid in the absence of the fluids to come into association. The normal disposition is for one of the fluids to go along in a coiled tube by means of a jacket having the second fluid. Both the heating and cooling impact may be helpful in saving the energy which is used in a chemical plant as well as in controlling the process.

Heat of Atomization The energy needed in separating one mole of a substance into atoms.

Heat of Combustion The energy released at the time when one mole of a substance inflates when oxygen is in excess.

Heat of Crystallization When one mole of a substance crystallizes from a drenched solution of this substance, the amount of energy released is the heat of crystallization.

Heat of Dissociation The energy needed to separate one mole of a substance into its component elements.

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Heat of Formation The energy transforms when one mole of a substance is established from its constituents.

Heat of Neutralization The energy released after the neutralization of one mole of an acid or base.

Heat of Reaction

Figure 62. Heat of reaction. Source: Image by Wikimedia.

The change in energy when molar amounts of provided substances is responsive completely.

Heat of Solution The energy transforms when one mole of a substance is submerged in a given solvent to dilution which is infinite (in practice, to formulate a dilute solution).

Helmholtz Function Refers to a thermodynamic function defined by F = U – TS where U stands for the internal energy, T for the thermodynamic temperature, and S is the entropy. It is an evaluation of the ability of a system in order to carry out

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useful work in the process of isothermal. The function is named after the German physiologist and physicist called Hermann Ludwig Ferdinand von Helmholtz (1821– 94).

Heme It is an iron having porphyrin which is the prosthetic group in hemoglobin, myoglobin, and few of the cytochromes.

Hemicellulose It refers to one of a group of mixtures that forms the amorphous matrix of the cell walls in plants along with pectic substances (and at times, in mature cells, together with lignin, gums, as well as mucilage). They are heteropolysaccharides in nature, that is, the polysaccharides constructed from more than one variety of sugar, for most of the parts, the hexoses (mannose and galactose) in addition to the pentoses (xylose and arabinose). They differ immensely in constituents between species. In a few seeds (for example, the endosperm of dates) hemicelluloses acts as a food store.

Hemin It refers to the hydrochloride form of heme. Hemin is said to be the crystalline form in which heme can be secluded and analyzed in the laboratory. The iron available is the trivalent phase (iron (III)). Hemin can be constructed to crystallize through the process of heating hemoglobin mildly along with acetic acid and sodium chloride. Variations of crystal forms are predominant.

Hemocyanin

Figure 63. Hemocyanin. Source: Image by Wikipedia.

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A blue color copper-containing blood pigment developed in many mollusks and arthropods. Hemocyanin is said to be the second most abundant blood pigment following hemoglobin and plays roles that are similar in performance as the carriers of oxygen in the blood. It is a pigment taking place in the blood of some of the invertebrates, identical in structure to hemoglobin.

Hemoglobin Refers to the pigment of the red blood cells found in humans and various other vertebrates that is accountable for the transfer of oxygen from the lungs to the other tissues. It is composed of a basic protein, globin, associated with four heme groups. Heme is a multiplex compound which contains an iron atom. The most significant attribute of hemoglobin is its capacity to amalgamate reversibly with one molecule of oxygen per iron atom in order to formulate oxyhemoglobin, which carries a bright red color. The iron is available in the divalent phase (iron (II)) and these stay uniform along with the binding of oxygen. There are differences in the polypeptide chains, producing various types of hemoglobin in disparate species. The binding of oxygen relies on the partial pressure of oxygen; high pressure helps in the construction of oxyhemoglobin and low pressure assists the liberation of oxygen.

Heparin A polysaccharide that obstructs the construction of thrombin from prothrombin that prevents the clotting of blood. It is applied in the aspects of medicine in the form of an anticoagulant.

Heptane (C7H16) A liquid alkane which contains no color and it is acquired from petroleum refining. It is applied in gasoline and in the form of a solvent.

Heterocyclic Compound It is a mixture that carries a ring which has more than one type of atom. Usually, heterocyclic compounds are said to be organic compounds with the minimum of having one atom in the ring that is surely not a carbon atom. The most common examples of this are Pyridine and glucose. The noncarbon atom is known as a hetero atom.

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Heterogeneous It is associating to more than one state. A heterogeneous compound, for example, has two or more definite phases. Heterogeneous catalysis incorporates a catalyst that is a distinct phase as compared to that of the reactants (commonly gaseous reactants moved through a solid catalyst).

Heterolytic Fission (Heterolysis) It refers to the diffusing of a covalent bond, in a way that both electrons of the bond persist together with one fraction. A negative ion as well as a  >  €®~€®Y

Hexamethylenetetramine (Hexamine; C6H12N4) Refers to a white crystalline organic compound produced through condensing methanol along with ammonia. It is applied as a fuel for outspanning stoves, in vulcanizing rubber, and also as a urinary disinfectant. In order to generate high explosive cyclonite, it can be nitrated.

Hexane (C6H14) A liquid alkane acquired from the light segment of crude oil. The prime use of hexane is done in gasoline in the form of a solvent.

Hexanedioic Acid A crystalline organic dicarboxylic acid which has no color that takes place in rosin. It is applied in the production of nylon.

Histamine

Figure 64. Histamine. Source: Image by Wikipedia.

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An amine formulated from the amino acid histidine through decarboxylation and generated mostly in connective tissue as a reaction to injury or allergic reaction. It results in contraction of smooth muscle, energizes gastric secretion of hydrochloric acid and pepsin, in addition to this it dilates blood vessels, which reduces blood pressure and gives rise to ˆ   % %     

Hofmann Degradation It is a technique of establishing primary amines out of the acid amides. The amide is refluxed with aqueous sodium hydroxide and bromine, that is: RCONH2 + NaOH + Br2~€&|Œ}‚Œ ‚}2O RCONHBr + OH– ~€&|ŒY‚}2|€&|ŒY‚~€YŒ&|‚– RNCO + 2OH–~ RNH2 + CO22– The reaction is a debasement in the manner that a carbon atom is withdrawn from the amide chain. It is named after August Wilhelm von Hofmann who was a prominent German chemist.

Holoenzyme A complex substance which is catalytically active and it is composed of an apoenzyme along with a coenzyme. The prior is accountable for the particularity of the holoenzyme although the latter demonstrates the behavior of the reaction.

Homocyclic Compound It is a compound having a ring constructed of the same atoms. The most common example of a homocyclic compound is Benzene.

Homogeneous Connected to a single phase, is a homogeneous compound, for example, consisting of only one state. In homogeneous catalysis, the catalyst possesses the identical phase in the form of the reactants. Homologous series A group of organic compounds having the same fundamental and operating group and containing a regular structural framework so that an individual member of the series varied from the next one by a permanent number of atoms. The members of a homologous series might be identified by a general formula. For instance, the homologous series of alkane alcohols CH3OH, C2H$OH, C3H7OH, has a usual formula CnH2n+1OH. Each member varied by CH2 from the other. Any two consecutive members of a pattern are known as homologs.

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Host–Guest Chemistry Refers to the branch of supramolecular chemistry where a molecular structure performs as a ‘host’ and accounts for holding an ion or molecule (the ‘guest’). The guest might be coordinated to the host or may be captivated by its structure. For instance, calixarenes are mixtures containing cup-shaped molecules that may take up guest molecules.

HPLC Refers to the liquid chromatography which is of high-performance; a sensitive analytical method, identical to the chromatography of gas-liquid but applying a liquid carrier. The carrier is particularly chosen for the specific substance to be discovered or determined.

Humectant A hygroscopic material applied for sustaining moisture levels. Glycerol, mannitol, and sorbitol are usually proving useful in foodstuffs, tobacco, etc.

Hydrate A compound correlated with water molecules. When water is tied up in a mixture it is called the water of crystallization.

Hydrazone

Figure 65. Hydrazone iodination.

Source: Image by Wikimedia.

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This refers to a type of organic compound having the C: NNH2 group, constructed by the reaction which takes place between an aldehyde or ketone as well as hydrazine (N2H4). The by-products of hydrazine were conventionally used to construct crystalline products, which carry high melting points that can be useful to characterize the initial aldehyde or ketone. Phenylhydrazone (C6H$NH.NH2), for example, gives out phenylhydrazones.

Hydride It is a mixture of hydrogen. Ionic hydrides are formulated with extremely electropositive elements and possess the H– ion (hydride ion). Non-metals construct covalent hydrides, like in methane (CH4) or silane (SiH4). The boron hydrides have insufficient electron covalent mixtures. Most of the transition metals dissolve hydrogen in order to form interstitial hydrides.

Hydrobromic Acid (HBr) A liquid which has no color and it is formulated by mixing hydrogen bromide in water. It denotes the typical attributes of a robust acid and it is an extreme reducing agent.

Hydrocarbon It is any mixture having only the elements that is carbon and hydrogen. Examples are the alkanes, alkynes, alkenes along with the aromatics for instance, benzene and naphthalene.

Hydrochloric Acid (HCl) A colorless liquid which is also fuming and it is formed through adding hydrogen chloride in water. Separation into ions is far reaching and hydrochloric acid depicts the typical attributes of a strong acid. Hydrochloric acid is applied in producing dyes, drugs, in addition to photographic materials.

Hydrocyanic Acid (Prussic Acid; HCN) An extremely poisonous yet feeble acid formulated when hydrogen cyanide gas disintegrates in water. Its salts are referred to as cyanides. Hydrogen cyanide is implemented in constructing acrylic plastics.

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!  !"# A liquid which has no color and it is constructed by dissolving hydrogen fluoride in water. It is a feeble acid, but will disintegrate most silicates and therefore can be applied to engrave glass. As it has the interatomic distance in HF comparatively small, the bond energy which is H–F is extremely high and hydrogen fluoride does not prove to be a good donor of protons. It does, however, make hydrogen bonds.

Hydrogen This refers to a gaseous element which is without any colors. Hydrogen possesses few similarities with the alkali metals (group 1) as well as the halogens (group 17), but is not generally categorized in any specific group of the periodic table. This element is present in abundance in the Universe and is regarded as the ninth most ample element in the crust of the Earth and atmosphere (by mass). It takes place generally in the form of either water or petroleum products; traces of molecular hydrogen are discovered in few of the natural gases present in the upper atmosphere. Symbol is as follows: H; m.p. 14.01 K; b.p. 20.28 K; d. 0.089 88 kg m–35/Z&=]#]€#//!“

Hydrogenation It is the reaction of a mixture with hydrogen. In organic chemistry, hydrogenation commonly stands for the addition of hydrogen to numerous bonds, sometimes with the assistance of a catalyst. Unsaturated natural liquid vegetable oils could be hydrogenated to construct fats that are saturated semisolid– a reaction applied in constructing different types of margarine.

Hydrogen bond Refers to an intermolecular bond in between the molecules where hydrogen is tied to a vigorous electronegative element. Bond polarization through the electronegative element X results in a positive charge on hydrogen ®¯YY}¯]    >       electronegative elements of adjoining molecules. The hydrogen bond is    ®¯YY}¯°®¯YY}¯°     '    /#$Y/}  bonding may take over the formulation of dimers (for instance, in carboxylic acids) and is implemented to elucidate the irregular extreme boiling points of H2O and HF. Hydrogen bonding is crucial in most of the biochemical

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systems. It takes place between bases mainly in the chains of DNA. It also takes place between groups of C=O and N–H in proteins, where it is accountable for sustaining the secondary structure.

Hydrogen Bromide (HBr) A sharp-smelling gas which is colorless and it is highly soluble in water. It is formed by direct combination of hydrogen along with bromine in the presence of a platinum catalyst or by the phosphorus tribromide reaction with water. It is soluble in water and provides hydrobromic acid.

Hydrogen Chloride (HCl) This refers to a gas which possesses no color that has an immense irritating odor and fumes resolutely in moist air. It is established by the action of concentrated sulfuric acid on sodium chloride. The gas is constructed industrially through the process of burning in chlorine, a stream of hydrogen. It is not specifically reactive but will take shapes of dense white clouds of ammonium chloride at the time of mixing it with ammonia. It is highly soluble in water and ionizes nearly all entirely in order to provide hydrochloric acid. Hydrogen chloride is applied in the production of compounds that are organic chlorine, for example, polyvinyl chloride (PVC).

Hydrogen Fluoride (HF) A liquid which contains no color formulated through the reaction of concentrated sulfuric acid on calcium fluoride. It gives rise to the toxic corrosive fumes and disintegrates rapidly in water in order to provide hydrofluoric acid. Hydrogen fluoride is unusual for hydrogen halides as the separate H–F units are connected into many substantial units, constructing uneven chains and rings. This is the outcome of hydrogen bonds that formulate in between the hydrogen in addition to the extremely electronegative fluoride ions. Hydrogen fluoride proves to be useful on a wide-scale in the form of a catalyst in the petroleum industry.

Hydrogen Ion It is a positively charged hydrogen atom, H+, i.e., a proton. Hydrogen ions are produced by all acids in water, in which they are hydrated to hydroxonium (hydronium) ions, H3O+. See acid; pH.

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Hydrogen Peroxide (H2O2) A syrupy liquid containing no color most commonly used in solution in water. However, it is uniform when pure, on contact with bases for instance, manganese (IV) oxide it provides oxygen, the manganese (IV) oxide performing as a catalyst: 2H2O2 ~ }2O + O2. Hydrogen peroxide can perform in the form of an oxidizing agent, transforming iron (II) ions to iron (III) ions, or even as a reducing agent together with potassium manganate (VII). It is applied as bleach and also in rocket fuel. The toughness of solutions is commonly provided as volume strength – the volume of oxygen (dm3) at STP provided by decomposition of 1 dm3 of the solution.

Hydrogensulfate Refers to an acidic salt or ester of sulfuric acid (H2SO4), whereby only one of the hydrogen atoms of an acid has been shifted by either a metal or by organic radical. An instance for this is sodium hydrogensulfate, NaHSO4.

Hydrogen   It is refers to a highly poisonous gas which contains no color and has an odor of bad eggs. Hydrogen sulfide is formulated by reacting hydrochloric acid along with iron (II) sulfide. It is tested for by fusing with lead nitrate, along with which it provides a black precipitate. Its aqueous solution is feebly acidic. Hydrogen sulfide lowers iron (III) chloride to iron (II) chloride, constructing hydrochloric acid together with yellow precipitate of sulfur. Hydrogen sulfide precipitates indissoluble sulfides, and is applied in the analysis which is qualitative. It blazes with a blue flame in oxygen in order to produce sulfur (IV) oxide along with water. Natural gas possesses a little hydrogen sulfide, which is withdrawn prior to the supply to the consumer.

!   It is an acidic salt or ester of sulfurous acid (that is H2SO3), where only one of the hydrogen atoms of an acid has been shifted by a metal or organic radical. The most common instance for this is sodium hydrogensulfite, NaHSO3.

Hydrolysis It is a reaction that takes place between a compound and water. An instance of this is the hydrolysis of an ester to provide a carboxylic acid along with an alcohol: CH3COOC2H$+ H2|~&}3COOH + C2H$OH.

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Hydroxyl Group A group (–OH) having hydrogen as well as oxygen, attributes of alcohols and phenols, and few of the hydroxides. It must not be confused with the (OH–) that is hydroxide ion.

Hyperconjugation The association of sigma bonds along with pi bonds. It is often explained in context of resonance framework of the type: C6H$CH3~&6H$CH2 –H+ so as to define the connection of the methyl group with the pi electrons of the benzene ring present in methylbenzene (toluene).

Hypertonic Solution It is a solution that contains osmotic pressure which is higher as compared to some other solution.

Hypotonic Solution It is a solution that consists of an osmotic pressure which is lower as compared to some other solution.

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I Ignis Fatuus Ignis fatuus is a light sometimes seen over marshy ground. It’s caused by methane produced by rotting vegetation, which is ignited by the presence of a small quantity of impulsively flammable phosphine (PH3).

Ignition Temperature Ignition temperature is the lowest temperature to which a particular substance can be heated before it ignites (without the use of a spark or flame). It is normally known as the auto ignition temperature.

Imide Refers to an organic compound comprising the group –CO.NH.CO–, i.e., a –NH group attached to two carbonyl groups. Simple imides have the common formula R1.CO.NH.CO.R2, in the formula R1 and R2 are alkyl or aryl groups. The group is recognized as the imido group, and this group can form part of a ring in cyclic imides.

Imine

Figure 66. Imine. Source: Image by Wikimedia.

Imine is an organic compound having the group C=N–, in which there is a double bond between the carbon and the nitrogen. A general formula for imines is R1R2C=N–R3, in the formula R1, R2, and R3 are hydrocarbon groups or hydrogen. They can be prepared by the reaction of aldehydes and ketones with primary amines. For instance, propanone (acetone; CH3COCH3) with ethylamine (C2H6NH2): CH3COCH3 + C2H6NH2~5&}3)2C=N–C2H6 + H2| ª          R1, R2, or R3 are aryl groups. Related compounds like oximes, hydrazones,

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and semicarbazones, in that the nitrogen is attached to an electronegative group, are stable enough and can be isolated.

Immiscible It is describing two or more liquids that will not mix, for example oil and water. After being shaken together and left to stand immiscible liquids form distinct layers.

Indene Indene is colorless combustible hydrocarbon. It has a benzene ring fused to a five-membered ring.

Indicator It is a compound that reversibly changes color depending on the availability or non-availability of a chemical element. In acid–base indicators the color relies upon the solution’s pH value in which it is dissolved. Examples of acid– base indicators are Methyl orange and phenolphthalein. Redox titrations need either a particular indicator that identifies one of the components of the chemical reaction (for example. starch for iodine, potassium thiocyanate for Fe3+) or true redox indicators in that the transition potential of the indicator between oxidized and reduced forms is important. The transition potential of a redox indicator is analogous to the transition pH in acid– base systems. Complex metric titrations need indicators that are complex with metal ions and change in color between the free and the complex state.

Indigo A blue organic dye happens (as a glucoside) in plants of the genus Indigofera. It is derived from indole, and is nowadays made synthetically.

Indole A colorless solid organic compound which is arises in coal tar as well as many plants, and is the basis of indigo and of several plant hormones. The indole molecule consists of a benzene ring fused to a pyrrole ring.

Inductive Effect Inductive effect is the effect in which substituent atoms or groups in an organic compound can attract (–I) or push away electrons (+I), creating

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polar bonds. Electron-attracting groups contain –NO2, –CN, –COOH, and the halogens. Electron releasing groups contain –OH, –NH2, –OR, and R, where R is an alkyl group. The reactivity of other parts of a molecule can be influenced by this effect. For instance, an electron-attracting group substituted on a benzene ring extracts electrons and creates the ring less susceptible to electrophilic substitution. More susceptible ring can be made by an electron-releasing group.

Infrared (IR) Electromagnetic radiation has longer wavelengths than visible radiation. The range of wavelength is approximately 0.7 μm to 1 mm. There are many materials transparent to visible light that are opaque to infrared, containing glass. Rock salt, quartz, germanium, or polyethene prisms and lenses are appropriate for use with infrared. Infrared radiation is formed by movement of charges on the molecular scale; i.e., by vibrational or rotational motion of molecules. `               and absorption spectra are used extensively in recognizing compounds. &       5&Y&%&&%&|%= > vibrational frequencies that correspond to bands in the infrared spectrum. `    [        compounds by classifying the availability of certain groups. They are   [   ’'         smaller wavelengths, infrared absorption corresponds to transitions between      %  [      molecules (by their moment of inertia).

Inner It is describing a ring compound that is formed, or considered as formed, by one portion of a molecule reacting with another. For instance, a lactam is an inner amide and a lactone is an inner ester.

Inorganic Chemistry The stream of chemistry is related with elements other than carbon and with the preparation, properties, and reactions of their compounds. Some simple carbon compounds are treated in inorganic chemistry, comprising carbon oxides, carbon disulfide, carbon halides, hydrogen cyanide, and some simple salts, like the cyanides, cyanates, carbonates, and hydrogen carbonates.

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Insertion Reaction Insertion reaction is defined as a reaction in which an atom or group is inserted between two other groups.

Insoluble Insoluble is defined as a compound which has a very low solubility (in a definite solvent).

Intermediate š š

A compound that requires further chemical treatment to create a    A transient chemical entity in a complex reaction.

Intermolecular Force Intermolecular force is defined as force of attraction between molecules, as illustrated from a force within the molecule (a chemical bond). Forces of attraction between molecules are the outcome of interactions between dipoles. For example: hydrogen bond; Van der Waals force.

Internal Energy Internal energy is defined as the energy of a system which is the sum of the kinetic and potential energies of its constituent particles (e.g., atoms and molecules). In case if the temperature of a substance is increased, by transferring energy to it, the internal energy increases (the particles move faster). In the same way, work done on or by a system is the reason for an increase or decrease in the internal energy. The first law of thermodynamics derives the relationship between heat, work, and internal energy. In some cases, the internal energy of a system is lightly pronounced as ‘heat’ or ‘heat energy.’ But strictly, this is not correct; heat is the transfer of energy as an effect of a difference in temperature.

Inversion The spatial rearrangement of atoms or groups of atoms in a dissymmetric molecule, giving rise to a product with a molecular configuration that is a mirror image of that of the original molecule.

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Iodine Iodine is a dark-violet volatile solid element belonging to the halogens (group 17, formerly VIIA, of the periodic table). It happens in seawater and is concentrated by numerous marine organisms in the form of iodides. Substantial deposits also occur in the form of iodates. There are so many organic iodine compounds.

Iodoethane Iodoethane is a colorless liquid haloalkane prepared by reaction of ethanol with iodine in the availability of red phosphorus.

Iodomethane (Methyl Iodide; CH3I) Iodomethane is a liquid haloalkane prepared by reaction of methanol with iodine in the availability of red phosphorus.

Ion Ion is defined as an atom or molecule which has a negative or positive charge because of dropping or acquiring one or more electrons.

Ion Exchange Ion exchange is a method which happens in certain insoluble materials that comprise ions equipped with ions in the surrounding medium. Zeolites, which are the first ion-exchange materials, were utilized for water softening. These have generally been substituted by synthetic resins prepared of an inert backbone material, for example polyphenylethene, to which ionic groups are weakly connected. In the case that the ions exchanged are positive, the resin is a cationic resin. An anionic resin exchanges negative ions. At the point when all present ions have been exchanged (for example sodium ions replacing calcium ions) the material can be redeveloped by passing concentrated solutions for example sodium chloride) through it. The calcium ions are then substituted by sodium ions. Ion-exchange methods are [            

Ionic Crystal A crystal made out of ions of two or more elements. The positive and negative ions are organized in certain arrangements and are held together by electrostatic attraction. A typical example of it is Sodium chloride.

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Ionic Radius Ionic radius is a measure of the effective radius of an ion in a compound. In case of an isolated ion, the perception is not very significant, as the ion is a nucleus enclosed by an ‘electron cloud.’ Values of ionic radii can be allocated, though, based on the distances between ions in crystals.

Ionic Strength For an ionic solution an amount can be introduced which emphasizes the     `±²i zi2 in the equation m stands for molality and z for the ionic charge. The summation is continued over all the various ions in the solution.

Ionization Ionization is the process of producing ions. There are numerous methods in which ions might be formed from atoms or molecules. In some chemical reactions, ionization happens by electrons transfer; for instance, sodium atoms and chlorine atoms react to form sodium chloride that have sodium ions (Na+) and chloride ions (Cl–). Some molecules can ionize in solution; acids, for instance, form hydrogen ions as in the reaction H2SO4~}+ + SO42– The ‘driving force’ for ionization in a solution is solvation of the ions by molecules of the solvent. H+, for instance, is solvated as a hydroxonium (hydronium) ion, H3O+.

Ionization Potential The energy essential for removal of an electron from an atom (or molecule

 =   %% _   ~ M+ + e–. It provides a degree of the ability of metals to form positive ions. The second ionization potential is the required energy for the removal of         ~2+ + 2e–. Ionization potentials specified in this manner are positive; frequently they are given in electronvolts. Ionization energy is the required energy to ionize one mole of the substance, and is generally specified in kilojoules per mole (kJ mol–1).

Ionizing Radiation It refers to radiation of adequately high energy to cause ionization. It might be short-wavelength electromagnetic radiation (ultraviolet, x-rays, or gamma rays) or streams of particles.

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Ion Pair A positive ion and a negative ion in close proximity in solution and detained by the force of attraction between their charges.

Isoenzyme It is an enzyme that occurs in various structural forms inside a single species. The isomeric forms all have the same molecular weight but differing structural patterns and qualities. Huge numbers of other enzymes are known to have isomeric forms; for instance, lactate dehydrogenase has five forms. Dissimilarities in the isoenzyme constitution of individuals can be illustrious by electrophoresis.

Isocyanide Test Isocyanide test is a test for the primary amine group in organic compounds. In an alcoholic solution of potassium hydroxide, the sample is warmed with trichloromethane. If a primary amine is present, the resulting isocyanide (RNC) has a typical odor of bad onions (and is very poisonous): CHCl3 + 3KOH + RNH2~€Œ&"^&"}2O

Isoelectronic Isoelectronic is defined as compounds in which the same number of electrons. For instance, carbon monoxide (CO) and nitrogen (N2) are isoelectronic.

Isomerism It is the presence of two or more chemical compounds having the same molecular formula but dissimilar structural formulae or dissimilar spatial arrangements of atoms. The different forms are identified as isomers. For instance, the compound C4H10 might be butane (with a straight chain of carbon atoms) or 2-methylpropane (CH3CH(CH3)CH3, with a branched chain). Structural isomerism is the kind of isomerism in that the structural formulae of the compounds differ. There are two major types. In one the isomers are not the same types of compounds. For instance: the compounds ethanol (C2H$OH) and methoxymethane (CH3OCH3), in both cases the formula is C2H6O but not the same functional groups. In the other kind of structural isomerism, the isomers differ in the position of a functional group in the molecule. For instance, the primary alcohol propan-1-ol (CH3CH2CH2OH) and the secondary alcohol

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propan-2-ol (CH3- CH(OH)CH3) are isomers; in both cases the molecular formula is C3H7OH.

Isothermal Change It is a process that happens when the temperature is constant. During an isothermal process, the system is in thermal equilibrium with its surroundings. For instance, a cylinder of gas in contact with a constant-temperature box might be compressed gradually by a piston. The work acts as energy that flows into the reservoir to retain the gas at the same temperature. Isothermal changes are differentiated with adiabatic changes, in that no energy arrives or leaves the system, and the temperature of the system is      ` ?      ˆ          ˆ    % >            >      these ideals.

Isotope One of two or more species of the same element but their mass numbers is different since of differing numbers of neutrons in their nuclei. The nuclei essentially have the same number of protons (an element is categorized by its proton number). Isotopes of the same element have very similar qualities as they have the same electron configuration, but differ to some extent in their physical qualities. An isotope which is not stable is called a radioactive isotope or radioisotope.

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J Jones Oxidation The reaction is that a secondary alcohol is oxidized to a ketone utilizing sodium chromate(VII) (Na2Cr2O7) in dilute sulfuric acid. The reaction comprises the creation of an intermediate chromate ester of the type R2HC–O–CrO3H.

Joule Joule is the SI unit of energy and work; joule is equal to the work done when the point of use of a force of one newton moves one meter in the direction of action of the force. 1 J = 1 N m. The joule is the unit of all types of energy.

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K Kairomone A chemical messenger emitted by an individual of a species and affecting a response in an individual of another species. This might be injurious to the producer of the kairomone, for instance various parasites are attracted to their hosts by an excreted kairomone.

Keratin One of a group of fibrous unsolvable sulfur-containing proteins (scleroproteins) originates in ectodermal cells of animals, as in hair, horns,  ¬   {    { { < {  „{  <{  >  %  „ keratins have a beta pleated sheet structure.

Ketene (keten) Ketene is a member of a group of organic compounds, common formula R2C:CO, in the formula R is hydrogen or an organic radical. The simplest member is the colorless gas ketene, CH2:CO; the other ketenes are colored since the double bonds presented. Ketenes are not stable and react with other unsaturated compounds to provide cyclic compounds.

Keto–Enol Tautomerism A variety of tautomerism is that a compound having the –CH2–CO– group (the keto form) interconverts with one having –CH=CH(OH)– (the enol) by hydrogen migration.

Ketone Ketone is a type of organic compound with the common formula RCOR, having two alkyl or aryl groups bound to a carbonyl group. They are prepared by oxidizing secondary alcohols (same as aldehydes are prepared from primary alcohols). Common examples are propanone (acetone, CH3COCH3) and butanone (methyl ethyl ketone, CH3COC2H$). The chemical reactions of ketones are the same as in many ways to those of aldehydes. The carbonyl group is polarized, and has positive charge on the carbon and negative

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charge on the oxygen. Therefore, nucleophilic addition can happen at the carbonyl group. Ketones thus: š

Go through additional reactions with hydrogen cyanide and

 5=  š Go through condensation reactions with hydroxylamine, hydrazine, and their derivatives. š Are reduced to (secondary) alcohols. They are not, though, simply oxidized. Strong oxidizing agents give a mixture of carboxylic acids. They do not react with Fehling’s solution or Tollen’s reagent, and do not simply polymerize.

Ketone Body One of a group of organic elements made in fat metabolism, and generally in the liver. Examples of ketone bodies are acetoacetic acid and acetone. Ketone bodies are the key fuel basis for resting skeletal muscle. In case if the body has less or no carbohydrate as a respiratory substrate, ketosis arises, in that more ketone bodies are made than the body can utilize.

Kilogram

Figure 67. An image showing Kg measuring instrument. Source: Image by Pxfuel.

Kilogram is the SI unit of mass, equivalent to the mass of the international sample of the kilogram that is a section of platinum–iridium reserved at Sèvres in France.

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Kilowatt-Hour Kilowatt-hour is a unit of energy, frequently electrical, equivalent to the energy transmitted by one kilowatt of power in one hour. The value of Kilowatt-hour is 3.6 × 106 joules.

Kinetics Kinetics is a stream of physical chemistry related with the study of rates of chemical reactions and the consequence of physical circumstances which impact the rate of reaction, for example; temperature, light, concentration, etc. The measurement of these rates in various circumstances provides facts on the mechanism of the reaction, i.e., on the structure of processes by which reactants are converted into products.

Krebs Cycle A complex and nearly universal cycle of reactions in that the acetyl group of acetyl CoA is oxidized to carbon dioxide and water, with the formation of a huge quantity of energy. It is the final common way for the oxidation of carbohydrates, fatty acids, and amino acids. It needs oxygen, and eukaryotes occur in the mitochondrial matrix. 2-carbon acetate reacts with 4-carbon oxaloacetate to form 6-carbon citrate, which is after that decarboxylated to reconstitute oxaloacetate. Some ATP is made by direct coupling with cycle reactions, but major making is coupled to the electron transport chain by the generation of reduced coenzymes, NADH and FADH2.

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L Label Label is a stable or radioactive ISOTOPE utilized to examine a chemical reaction. Labeling is a general way of examining chemical reaction mechanisms. A typical example is the hydrolysis of an ester to provide a carboxylic acid and an alcohol, like in: H2O + CH3COOCH3~&}3COOH + CH3OH It is likely to examine the mechanism by utilizing an ester enriched with the isotope 18O. In the case if the 18O is on the oxygen attached to the carbonyl, it is found that it ends up in the alcohol rather than the acid: H2O + CH3CO18|}~&}3COOH + CH3 18OH This, and same trials utilizing labeled water and labeling of the carbonyl oxygen, support to mechanism establishment.

Lactam Lactam is a category of organic compound having the –NH.CO– group as part of a ring in the molecule. Lactams can be viewed as formed from a straight-chain compound which has an amino group (–NH2) at molecule’s one end and at the other end a carboxylic acid group (–COOH); i.e., from an amino acid. The reaction of the amine group with the carboxylic acid group, with elimination of water, leads to the cyclic lactam that is therefore an internal (or inner) amide. Lactams can be in an alternative tautomeric form in that the hydrogen atom has drifted from the nitrogen onto the O of the carbonyl. This, the lactam form, contains the group –N=C(OH)–.

Lactone Lactone is a category of organic compound having the group –O.CO– as part of a ring in the molecule. A lactone can be viewed as made from a compound with an alcohol (–OH) group on one end of the chain and on the other end a carboxylic acid (–COOH) group. The lactone then results from reaction of the –OH group with the –COOH group; meaning of that, it is an internal ester.

Lactose Lactose is a SUGAR originating in milk. It is a disaccharide. It is a sugar composed of galactose and glucose subunits.

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Ladenburg Benzene An improper structure for benzene in that the six carbon atoms are at the corners of a triangular prism. It is so-called Albert Ladenburg (1842–1911). The actual compound, known as prismane, was created in 1973.

Lake A pigment made by precipitating an organic dyestuff on an inorganic oxide, hydroxide, or salt.

Lamellar Compound Lamellar compound is a compound having a crystal structure made of thin plates or layers. Silicates form many compounds with distinct layers. Classic examples are talc (Mg3(OH)2Si4O10) and pyrophyllite (Al2(OH)2Si4O10).

Lanolin

Figure 68. Packaging of Lanolin cream. Source: image by open beauty facts.

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Lanolin is a yellowish viscous material found from wool fat. It comprises cholesterol and terpene compounds, and is utilized in cosmetics, in ointments as well as in treating leather.

Laser It is an abbreviation for Light Amplification by Stimulated Emission of Radiation. A laser device generates high-intensity, monochromatic, coherent beams of light. In the procedure of laser, the molecules of a sample (like ruby doped with Cr3+ ions) are endorsed to an excited state. As the sample is in a cavity between two reflective surfaces, while a molecule releases impulsively, the photon so produced ricochets backward and forward. In this technique other molecules are stimulated to emit photons of equal energy. In a case if one of the reflective surfaces is moderately transmitting this radiation can be tapped.

Latent Heat Latent heat is the heat evolved or absorbed at the time a substance changes its physical state, for example, in fusion the latent heat is the heat absorbed when a substance changes its physical state from a solid to a liquid.

Latex Latex is a liquid found in various flowering plants enclosed in special cells or vessels termed laticifers (or laticiferous vessels). It is a complex variable substance which might have terpenes (for example. rubber), resins, tannins, waxes, alkaloids, sugar, starch, enzymes, crystals, etc. Usually, it is milky in presence but might be colorless, orange, or brown. Function of it is obscure, yet may be involved in wound healing and a repository for excretory substances. Marketable rubber originates from the latex of the rubber plants Ficus elastica and Hevea brasiliensis. Opium originates from alkaloids found in the latex of the opium poppy.

Lattice Lattice is a three-dimensional arrangement of points. It is used in describing the positions of the particles such as atoms, molecules and ions, in a crystalline solid. The structure of the lattice can be examined by the application of x-ray diffraction techniques.

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Leaching It is a process of washing out of a soluble material from an insoluble solid by making use of a solvent. This is usually carried out in batch tanks or by dispersing the crushed solid in a liquid.

Lead Tetraethyl Lead tetraethyl is a poisonous liquid. It is insoluble in water, though soluble in organic solvents. It is basically made by the reaction of an alloy of lead and sodium with chloroethane. The end-product is obtained by the technique of steam distillation. Earlier, it was extensively used as an additive in internalcombustion engine fuel in order to increase its octane number and thus prevent pre-ignition or knocking.

Leaving Group It is a group that leaves a molecule in elimination or substitution reaction. The nature of the leaving group is a key factor in the progress of a reaction.

Liebig Condenser It is a simple type of laboratory condenser. It comprises a straight glass tube, in which the vapor is condensed. Also, it is a surrounding glass jacket through which cooling water flows. It is named after the German chemist Justus von Liebig.

Ligand Ligand is a molecule or ion that forms a coordinate bond to a metal atom or ion in a complex.

Light It is a form of electromagnetic radiation which is able to be detected by the human eye. Its wavelength ranges between 400 nm (far red) to about 700 nm (far violet). The boundaries are not precise as individuals vary in their capability of detecting extreme wavelengths.

Lignin It is one of the main structural materials of vascular plants. It is one of the main constituents of wood, along with cellulose. Lignified tissues include

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xylem and sclerenchyma. Lignin is deposited during secondary thickening

  ?    >>  $Y"/”  $/”   > `  ?>      is derived from sugars through aromatic alcohols.

Lignite   

            ‰$”           moisture content.

Ligroin A mixture of hydrocarbons obtained from petroleum and highly used as a   >`     ž/ #/Z&

Line Spectrum It is a spectrum which is composed of a number of discrete lines equivalent to single wavelengths of emitted or absorbed radiation. Line spectra are mainly produced by atoms or monatomic ions present in gases. Each line corresponds to a change in electron orbit, with absorption or emission of radiations.

Linoleic Acid An unsaturated carboxylic acid that is present in linseed oil and various other plant oils. It contains two double bonds.

Linseed Oil Oil extracted from the seeds of flax or linseed. It gets hard on exposure to air, as it contains linoleic acid. Most often, it is used in enamels, putty, paints, and varnishes.

Lipid A collective term which is used to define a group of substances present in cells that are characterized by their solubility in their organic solvents such as benzene and ether, and their absence of solubility in water. In terms of function as well as structure, the group is rather heterogeneous. In addition, they perform following biological functions-

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š š š

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They form basic structural units of cellular membranes as well as cytologically distinct subcellular bodies such as mitochondria and chloroplasts; They are compartmentalizing units for metabolically active proteins that are mainly localized in membranes; They are a store of chemical energy and carbon skeletons; and They are primary transport systems of nonpolar material through    ˆ %         lipid hormones, for example, the steroid hormones and lipid vitamins.

Lipoic Acid Lipoic acid is a sulfur containing fatty acid. It is mainly found in a wide range of natural materials. It is really significant as a coenzyme for some of the dehydrogenase enzymes, especially pyruvate dehydrogenase, which catalyzes the dehydrogenation of pyruvic acid to form acetyl-CoA. Further, lipoic acid is characterized with the water-soluble B vitamins. It has not yet been demonstrated to be needed in the diet of higher animals.

Lipopolysaccharide It is a conjugated polysaccharide in which the noncarbohydrate part is a lipid. Lipopolysaccharides are a constituent of the cell walls of certain bacteria.

Lipoprotein It is a kind of conjugated protein which is formed by the combination of a protein with a lipid. In the blood of humans and other mammals, cholesterol, phospholipids and triglycerides, linked with different kinds of plasma proteins to form lipoproteins. These are particles with diameters ranging  !$ !/%    `  %  largest lipoproteins are the very low-density lipoproteins (VLDLs) that are   >      /”  ¬ \ lipoproteins (LDLs) are formed in plasma from VLDLs and comprise more  $/”         >    tissues. An excess of LDLs in the blood is a key factor in the development of fatty arterial deposits as well as cardiovascular disease. High density   5}ƒ¬=%    /”  %      plasma lipoproteins. They function in transporting cholesterol from tissues to the liver.

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$%  & ' Abbreviated as LNG and it is liquid methane obtained from natural gas and is used as a fuel.

$%     ' Abbreviated as LPG and it is a mixture of liquefied hydrocarbon gases (especially propane) that is extracted from petroleum. Most often, it is used as a fuel for heating as well as internal combustion engines.

Liquid Liquid is a state of matter in which the particles of a particular substance are loosely bound by the intermolecular force. The weakness of the intermolecular force allows the movement of particles and as a result, liquids can change their shape within a fixed volume. The liquid state lacks the order of the solid state. Therefore, amorphous materials, such as glass, in which the particles are disordered and can move relative to each other, and they can also be classed as liquids.

Liter A unit of volume defined as 10–3 meter3; i.e., 1000 cm3. The milliliter (ml) is hence the same as the cubic centimeter (cm3). Though, the name is not suggested for precise measurements as the liter was formerly defined as the >   {     ‰Z&    this definition, one liter is the same as 1000.028 cubic centimeters.

Lithium Tetrahydridoaluminate(III) A kind of white solid produced by the action of lithium hydride on aluminum chloride, hydride being in excess amount. It reacts violently with water. It is also known as a powerful reducing agent. It reduces ketones and carboxylic acids to their corresponding alcohols. In the field of inorganic chemistry, it is used in the preparation of hydrides.

Litmus Litmus is a natural pigment that changes color while coming in contact with   {  > } ž"%   } ‰$ is red. Therefore, it gives a rough indication of the acidity or basicity of a solution. Litmus is used both in solution and as litmus paper.

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Lixiviation It is the process of separating soluble components from a mixture by washing them out with water.

Localized Bond It can be defined as a bond in which the electrons contributing to the bond remain between the two atoms concerned, that is, the bonding orbital is localized.

Lone Pair Lone pair is a pair of valence electrons that have opposite spin. They are located together on one atom, which means they are not shared as in a covalent bond. Lone pairs occupy similar positions in space to bond pairs and are highly responsible for the shapes of molecules. A molecule with a lone pair can donate the pair of electrons to an electron acceptor, such as H+ or a metal ion, to form coordinate bonds.

Low-Density Lipoprotein (LDL) ¬ƒ¬       %      /Y$     `  found in blood plasma and helps in transporting cholesterol to tissue cells. It is bounded by a single layer of phospholipid and free cholesterol, which further encloses a core of cholesterol esterified to a long-chain fatty acid. These are single large proteins called apo-B, embedded in the surface layer, which assists in binding of the LDL to cell-surface receptors. LDLs are transported into cells by a process called receptor-mediated endocytosis. The cholesterol is incorporated into cell membranes or stored as lipid droplets. High concentrations of LDLs in the blood have been linked with an increased risk of atherosclerosis, that is, ‘hardening of the arteries.’

Lowering of Vapor Pressure It can be described as a colligative property of solutions in which the vapor pressure of a solvent is lowered when a solute is introduced. When both solute and solvent are volatile, the effect of increasing the solute concentration is to lower the partial vapor pressure of each component. When the solute is a solid of negligible vapor pressure, the dropping of the vapor pressure of the solution is directly proportional to the number of species being introduced instead of their nature and the proportionality constant is considered as a

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general solvent property. As a result, the introduction of the same number of moles of any solute results in the same lowering of vapor pressure, if dissociation does not take place. The effect is doubled, if the solute dissociates into two species on dissolution. The kinetic model for the lowering of vapor pressure considers the solute molecules as occupying part of the surface of the liquid phase and thus, restricting the escape of solvent molecules.

Luminescence The emission of radiation from a substance in which the particles have absorbed energy and gone into excited states. Later, they return to lower energy states with the emission of electromagnetic radiation. If the luminescence remains even after the source of excitation is removed, then it is known as phosphorescence; if not, it is known as fluorescence.

Lutein It is the most common of the xanthophyll pigments. It is mainly found in green leaves and certain algae, such as the Rhodophyceae.

Lux It is the SI unit of illumination, which is equal to the illumination produced by a luminous flux of one lumen falling on a surface of one square meter. Mathematically, 1 lux = lm / m2.

Lyophilic In the shorter term, it is solvent attracting. When the solvent is water, the word hydrophilic is mostly used. The terms are applied to: š

š

Ions or groups on a molecule- In aqueous or other polar solutions ions, any of the polar groups are lyophilic. For an instance, the –COO– group on soap is the lyophilic (hydrophilic) part of the molecule. The dispersed phase in colloids- In lyophilic colloids, the    >        >%    colloids are usually stable.

Lyophobic In a shorter term, it is solvent repelling. When the solvent is water, the word hydrophobic is often used. The terms are applied to:

Key Concepts in Chemistry

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š

157

Ions or groups on a molecule- In aqueous or other polar solvents, the lyophobic group will be the nonpolar. For instance, the hydrocarbon group on a soap molecule is the lyophobic (hydrophobic) part. The dispersed phase in colloids- And lyophobic colloids, the dispersed particles are not solvated while, on the other hand, the colloid is easily solvated. Gold and sulfur sols can be the examples.

Lysergic Acid Diethylamide (LSD) The initials LSD come from the German form of its chemical’s name, Lysergic Saure-Diathylamide. It is a synthetic organic compound. It has physiological effects that are similar to those produced by alkaloids in some of the fungi. Even if ingested in small quantities, it produces hallucinations and mental disturbances.

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M Macromolecular Crystal A crystal is made up of atoms that are linked together via covalent bonds to form massive three-dimensional or two-dimensional structures. An example would be a diamond.

Magnetism The study of the nature and causes of magnetic force fields, as well as how they impact various objects. Moving charge produces magnetic fields, either on a large scale (as in a current in a coil generating an electromagnet) or on a microscopic scale (moving charges in atoms). It is universally believed that the magnetism of the Earth and that of other planets, stars, and galaxies are caused by the same phenomenon. Substances can be categorized according to how samples interact with fields. The type of atom causes different sorts of magnetic activity. Diamagnetism, which occurs in all substances, is caused by electron orbital mobility. Paramagnetism is caused by electron spin and is a characteristic of materials having unpaired electrons. It is especially relevant in transition-metal chemistry, where complexes frequently comprise unpaired electrons. Magnetic measurements often provide insight into the bonding in these complexes. The strongest effect, ferromagnetism, also includes electron spin and the alignment of magnetic moments in domains.

Malic Acid A colorless crystalline carboxylic acid occurs in unripe fruits. It has an apple flavor and is used in food flavorings.

Maltose A sugar present in cereal seeds that are germinating. It is a disaccharide that is made up of two glucose molecules. Maltose is an essential component in the hydrolysis of starch by enzymes. It is then hydrolyzed to make glucose.

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Mannitol A soluble hexahydric alcohol found in a variety of plants and fungi. It is utilized in pharmaceuticals and as a sweetener (especially in foods for people with diabetes). It is a sorbitol isomer.

Mannose A simple sugar that is present in various polysaccharides. It is an isomeric aldohexose containing glucose.

Manometer A pressure gauging device A U-shaped glass tube with mercury or another liquid is an example of a simple kind. The difference in liquid heights indicates the pressure difference between the tube’s arms.

Mass Mass is a measurement of the amount of matter in a subject. A body’s mass is calculated in two ways: its inertial mass defines its inclination to resist change in motion, and its gravitational mass determines its gravitational attraction to other masses. The kilogram is the SI unit of mass.

Mass Action It is the principle that the rate of a chemical reaction at a consistent temperature is directly proportional to the active mass of the reactants, where the active mass is taken as a solution concentration or the gas reaction partial pressure. The law of mass action states, with reference to the reaction A + ‚~ %  {¤³¤‚³ ¤³       of A, [B] for the concentration of B, and k is the constant dependent on the reaction. Active mass as a concentration or partial pressure is only true if the reacting molecules have no interaction or interference. Typically, in order to get the real active mass, the concentration must be multiplied by an activity coefficient.

Mass Spectrometer An apparatus to produce and analyze ions based on the charge/mass ratio. J. §  5#ž$ŽY#“‰/=% ‚ %     > ions from a discharge tube that were redirected by parallel electric and magnetic fields at right angles to the beam in his early experiments. Every

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ion type produced a parabola on a picture plate (a mass spectrograph). The ‚       ¥    5#ž!!Y#“‰$=       enhance its design. The ions are commonly generated by ionizing a gas with electrons in current devices. From this ion source the positive ions are propelled to a high vacuum area. The ion stream is bent and focused here by a mixture of                     ions fall on a detector. As a result, the ions can be examined based on their mass, yielding a mass spectrum of the material.

Matrix It is a prolonged solid phase containing particles of a separate solid phase.

Mechanism It is a detailed account of the events that occur during a chemical reaction. It is a theoretical framework that explains the outcome of bonding electrons and shows which bonds are established and which are broken. For example, in the chlorination of methane to produce chloromethane: š š š

Q#&&~& Q&š&}4~}&&}3 Step 3: CH3š&&~&}3Cl + Cl

Melamine A white solid organic compound with a six-membered heterocyclic ring comprising alternate carbon and nitrogen atoms and three amino groups connected to the carbons. Melamine resins, which are essential thermosetting polymers, are produced by condensation polymerization with methanal or other aldehydes.

Melting (Fusion) It is the process of converting a solid to a liquid using heat or pressure.

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Figure 69. Melting of ice in a glass. Source: Image by Wikimedia Commons.

Melting Point Refers to the temperature of a solid at the standard pressure, at which it is in equilibrium with its liquid phase and above which the solid melts. For a certain solid, this temperature is always the same. Ionically bound materials often contain significantly higher melting temperatures than those with covalent or intermolecular interactions.

Membrane It is a thin, malleable sheet of tissue or another substance that serves as a barrier. The membrane might be natural (as in cells or skin) or synthetic variations of natural materials (such as cellulose derivatives or rubbers). Membranes are placed atop porous materials, such as porcelain, in many physicochemical experiments to give mechanical strength. Membranes are permeable to some extent in general. Membranes can be created to allow other molecules and micromolecular substances to pass through. Concentration variations at a membrane result in a variety of membrane-equilibrium research, including osmosis, dialysis, and    %  

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Metabolism It refers to the biological reactions that occur within cells. Metabolites refer to molecules that participate in these events as either a reactant or a product. Some are made within the organism, whereas others must be consumed as food. Metabolic reactions are typically carried out in tiny steps that form a metabolic route. This involves catabolism, the breakdown of molecules to provide energy, and anabolism, the formation of more complex molecules and structures from simpler molecules.

Metallic Bond A bond established between atoms of a metallic element in its zero-oxidation state and an array of atoms with similar properties. Each atom outside electrons is thought to contribute to an “electron gas” that fills the entire crystal of the metal. The strength of the metallic bond is provided by the attraction of the positive atomic cores to the negative electron gas.

Metallocene A sandwich compound that consists of a metal atom or ion coordinated to two cyclopentadienyl ions. The most common example is Ferrocene (Fe(C$H$)2).

Metalloid Is any of a group of chemical elements with characteristics that fall in between metals and nonmetals. Germanium, arsenic, and tellurium are a few examples.

Metastable Species The excited state of an atom, ion, or molecule with a relatively lengthy lifetime before it returns to its ground state. Some chemical processes employ metastable substances as intermediates.

Metastable State Is a state of a system or body that appears to be in stable equilibrium but can settle into a lower energy state if disturbed. Supercooled water, for example, _   /Z&5   =€ [ happens when a little crystal of ice or dust (for example) is injected.

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Meter The SI base unit of length, given as the distance covered by light in vacuum  #J5““ !“ ‰$ž ´ #/ž=          #“ž"     #“Ž!    _  #Ž$/!Ž"!" >  vacuum correlating to the 86Kr atom’s transition between levels 2p10 and $$

Methanal An aldehyde that is colorless and gaseous. It is produced through the

?     5 $//Z&   >  =&}3OH + O2~ 2HCOH + 2H2O. The substance is utilized in the production of UREA– FORMALDEHYDE RESINS. Formalin is a water-based solution of    5‰/”= `           > > When a methanal aqueous solution is evaporated, a polymer – polymethanal – is formed: –O–CH2–O–CH2–O–CH2–. This was originally known as paraformaldehyde.

Methane An alkane that is gaseous. Natural gas is 99 percent methane, and it serves as a critical starting material for the organic-chemicals sector. Methane can be directly chlorinated to make the more reactive chloromethanes, or it can be ‘reformed’ through partial oxidation or steam to yield mixes of carbon oxides and hydrogen. Methane is the simplest organic chemical and the first member of the homologous sequence of alkanes.

Methanoic Acid A liquid carboxylic acid produced by Sulfuric acid reacting with sodium methanoate (NaOOCH). It is a powerful reducing agent. Methanoic acid is the chemical responsible for ant and nettle stings.

Methanol A colorless liquid alcohol used as a solvent and in the production of methanal (formaldehyde) for the plastics and pharmaceutical industries. Methanol was first created through the distillation of wood. It is now produced using the catalytic oxidation of methane via natural gas.

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Methylamine It is a colorless flammable gas with an ammonia-like odor. It is the most basic primary amine, and it is used to make herbicides and other organic compounds.

Methylated Spirits ˜      5  ? “$”=%5  /$”=%  a blue dye added to it. This denatures the ethanol, allowing it to be sold without excise duty for use as a fuel and solvent.

Methylbenzene A colorless liquid hydrocarbon that is structurally and chemically similar to benzene. Since methylbenzene is less harmful than benzene, it is more commonly employed, particularly as a solvent. TNT (trinitrotoluene) production involves large volumes of methylbenzene. Methylbenzene can be procured by fractional distilling of coal tar or manufactured from methylcyclohexane (a component of some crude oils): C6H11CH3~&6H$CH3 + 3H2. At high temperatures and pressures, aluminum and molybdenum oxide catalyst are used.

Methyl Cyanide It is a pleasant-smelling toxic colorless liquid organic nitrile and a polar solvent that is commonly used to dissolve both inorganic and organic molecules.

Methyl Methacrylate It is the methyl ester of methacrylic acid, which is utilized in the production of acrylic polymers such as Plexiglas (polymethylmethacrylate).

Methyl Orange An acid–base indicator that is red in solutions with a pH less than 3 and yellow in solutions with a pH more than 4.4. Methyl orange is appropriate for titrations of acids with relatively weak bases, such as sodium carbonate, because the transition range is majorly on the acid side.

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Methylphenol A benzene ring with both methyl and hydroxyl groups substituted on it. There are three isomers, each with the methyl group in the 2–, 3–, and 4– positions. Coal tar can be used to create a mixture of the isomers. It is employed as a germicide (known as Lysol).

Methyl Red It is an acid–base indicator which is red in solutions with a pH less than 4.2 and yellow in solutions with a pH more than 6.3. It is frequently used for the same types of titrations as methyl orange, but its transition range is closer to neutral (pH7) than that of methyl orange. The two molecules have a similar structure.

Methyl Salicylate It is the methyl ester of salicylic acid found in several plants. It is absorbed by the skin and used to treat rheumatic symptoms. It is also utilized as a flavoring agent in many cuisines and used in perfumes.

Metric System A unit system based on the meter and the kilogram that employs multiples and submultiples of ten. Scientific metric systems of units include SI units, C.G.S. units, and M.K.S. units.

Microwaves It is a type of electromagnetic radiation with wavelengths ranging from about 1 mm (where it combines with infrared) to about 120 mm (bordering on radio waves). Microwaves are generated by a variety of electronic devices and are frequently transmitted over short distances via rectangular-sectioned tubes known as waveguides. Microwave spectra can reveal information about the rotational energy levels of specific molecules.

Migration š š

The transfer of an atom, group, or double bond from one location in a molecule to another. `  > 

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Mineral Acid It is an inorganic acid, particularly one that is widely utilized commercially. Hydrochloric, nitric, and sulfuric acids are a few examples.

Mirror Image A shape that is similar to another except that its structure is inverted, as if seen via a mirror. An object cannot be projected on its mirror image if it is not symmetrical. The left hand, for example, is a mirror copy of the right hand.

Miscible Refers to the combinations of chemicals which produce only one phase upon mixing; that is, substances that dissolve in each other.

Mixed Indicator It is a combination of two or more indicators to reduce the pH range or increase the color change, etc.

Mixture Mixture refers to two or more compounds that create a system with no chemical bonding between them. The molecules of the substances are mixed in homogeneous mixes (e.g., solutions or gas mixtures), and there is only one phase. Different phases can be observed in heterogeneous mixtures (for example, gunpowder or certain metals). Mixtures vary from chemical compounds in the following ways: š š

The chemical properties of a mixture’s components are the same as those of pure substances. The mixture can be separated mechanically or physically (through distillation or crystallization).

mmHg (millimeter of mercury) A former pressure unit expressed as the pressure required to support a onemillimeter-high column of mercury under specific conditions. It is equivalent to 133.322 4 Pa and is nearly identical to a torr.

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Molar (1) A physical quantity expressed as a fraction of the amount of substance. The amount of substance will nearly always be expressed in moles. For instance, volume (V) divided by the number of moles (n) equals molar volume Vm = v/n. (2) A solution containing one mole of solute per cubic decimeter of solvent

Molarity It is a measurement of solution concentration determined by the number of molecules or ions present instead of the mass of solute in any given volume of solution. The molarity (M) of a substance is the number of moles of solute    5=/$            /$´5#"$$=}&3 of solution.

Mole It is the SI base unit of amount of substance, given by the amount of substance comprising as many elementary entities as there are atoms in 0.012 kilogram of 12C. Atoms, molecules, ions, electrons, photons, and other elementary entities must be stated. The amount of substance is proportional to the number of entities, with the Avogadro number serving as the proportionality     Ž//‰$´#/"       mole of an element with relative atomic mass A will be A grams – this mass was originally known as one gram-atom of the element.

Molecular Crystal It is a crystal wherein molecules, rather than atoms, occupy the lattice points. Molecular crystals have low melting points since the forces holding the molecules together are weak. When the molecules are tiny, the crystal structure resembles a densely packed configuration.

Molecularity The number of reacting molecules in a chemical reaction’s various steps. Therefore, a unimolecular step has molecularity 1, a bimolecular step has molecularity 2, and so on. The molecularity of a reaction is always an integer, although the order of a reaction may not always be. The molecularity of a reaction reveals nothing about the mechanism through which it occurs.

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Molecular Sieve A material that allows molecules of a narrow size range to pass through, allowing volatile mixtures to be segregated. In their molecular structure, zeolites and other metal aluminum silicates can be made with pores of consistent sizes. Some molecules penetrate these pores and become caught when a sample is passed through a column packed with granules of this substance. The remainder of the mixture flows through the column’s interstices. Heat can be used to free the trapped molecules. In chemistry and biochemistry laboratories, molecular-sieve chromatography is broadly ©     >    > The sieve is a polysaccharide-based continuous gel. Molecules bigger than the greatest pore size are completely eliminated from the column in this situation.

Molecular Spectrum It is the spectrum of absorption or emission that a molecule exhibits. Molecular spectra are typically band spectra.

Molecule A particle created by combining atoms in a whole-number ratio. A molecule of an element (with the same combining atoms, such as O2) or of a compound (with different combining atoms, such as HCl) maintains the properties of that element or compound. As a result, any amount of a substance is a collection of numerous similar molecules. The typical molecular size ranges from 10–10 to 10–9 m. Many natural product molecules are so enormous that they are referred to as giant molecules (macromolecules); they can contain thousands of atoms and have complex structural formulas that demand extremely advanced procedures to locate.

Mole Fraction It refers to the number of moles in a mixture of a given component divided by the total number of moles in each component. Component A’s mole fraction is nA/(nA + nB + nC +...), where nA denotes the number of moles of A, and so on.

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Monobasic Acid Acid with one acidic hydrogen alone and an example is ethanoic acid, CH3COOH.

Monosaccharide A sugar incapable of hydrolysis in order to produce simpler carbohydrates with lower carbon content, examples include glucose and fructose.

Monosodium Glutamate (MSG) A white crystalline solid substance derived from soya-bean protein. It is a sodium salt of glutamic acid that is used as a taste enhancer in Chinese cuisine. In certain individuals, monosodium glutamate might induce an allergic response.

Mordant It is an inorganic chemical that is used to fix dye in fabric. The mordant (for example, aluminum hydroxide or chromium salts) precipitates in the fibers of the fabric, and the dye subsequently absorbs in the particles.

Morphine An alkaloid found in opium, from the poppy Papaver somniferum. It is used to treat significant pain. A derivative is the drug heroin.

Multicenter Bond It is a two-electron bond created by the overlap of orbitals from many atoms (usually 3). Bridging in diborane is thought to occur as a result of the overlap of a sp3 hybrid orbital from each boron atom with the 1s orbital on the hydrogen atom. This type of multicenter bond is known as a two-electron three-center bond.

Multiple Bond It is a bond between two atoms that involves more than one pair of electrons, such as a double or triple bond. This additional bonding is caused by the convergence of atomic orbitals perpendicular to the internuclear axis, which results in an increase in electron density above and below the axis.

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Such bonds are known as pi bonds. (The bond along the axis is known as a sigma bond.)

Mutarotation Change in the optical rotation of a solution over time as a result of an optical isomer converting into a new one.

Myoglobin A globular protein composed of a heme group along with a single polypeptide chain. It takes place in muscle tissue, acting as storage for oxygen.

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N NAD (Nicotinamide Adenine Dinucleotide) NAD is a nicotinic acid derivative that works as a coenzyme in electrontransfer processes (e.g., the electron-transport chain). Its function is to transport hydrogen atoms; its reduced form is written NADH.

NADP Nicotinamide adenine dinucleotide phosphate is a coenzyme that functions similarly to NAD. NADPH is the reduced form that works as an electron donor in several synthetic reactions.

Nanotube A tubular structure of a few nanometers in diameter (1nm = 10–9 m). Carbon structures known as bucky tubes, which have a structure akin to buckminsterfullerene, are examples of nanotubes. Nanotubes have sparked interest as potential microscopic probes in experiments, semiconductor materials, and as a component of composite materials. Nanotubes can also be created by connecting amino acids together to form tubular polypeptide structures.

Naphtha A hydrocarbon combination derived from coal and petroleum. It has a    !/Y#Ž/Z&     >      material in the production of a variety of other organic compounds.

Naphthalene (C10H8) It is a white crystalline substance with a characteristic mothball odor. Naphthalene is obtained by fractional crystallization and is found in both the middle- and heavy-oil fractions of crude oil. It is used to make benzene1,2-dicarboxylic anhydride (phthalic anhydride), which is then used to make plastics and dyes. Naphthalene has a benzene-like structure, with two six-membered rings fused together. The reactions are typical of aromatic compounds.

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Nascent Hydrogen It is a highly reactive form of hydrogen that is thought to exist for a brief period of time between its production (e.g., by the action of dilute acid on magnesium) and its emergence as bubbles of regular hydrogen gas. Part of the free energy of the manufacturing reaction is thought to remain with the hydrogen molecules for a brief time. Nascent hydrogen can be utilized to create phosphorus, arsenic, and antimony hydrides, which are not easily produced from regular hydrogen.

Natural Gas Gas obtained from subsurface reserves and frequently related with petroleum         5  ž$”=   >   hydrocarbons (ethane, propane, and butane).

Neighboring-Group Participation A consequence in an organic reaction in which groups nearing the point of reaction influence the rate of reaction or the stereochemistry of the products in some manner.

Neoprene A form of synthetic RUBBER produced through the polymerization of 2-chlorobuta-1,2,-diene (H2C:CHCCl:CH2). Natural rubbers are less resistant to oil, chemicals, and temperature than synthetic rubbers.

Neutralization In volumetric analysis, it is the stoichiometric reaction of an acid and a base. Indicators are used to detect the neutralization or end point.

Neutron Diffraction It is a method of determining structure for solids, liquids, and gases which employ neutrons’ quantum mechanical wave nature. Thermal neutrons with > {   //$*  >  >     0.1 nanometer rendering them excellent for studying the atomic structure of matter. Given that a neutron has a nonzero magnetic moment it interacts with both nuclear magnetic moments and unpaired electron magnetic moments. This characteristic is very useful for determining the locations of hydrogen    `    ?\ 

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as x-rays interact with electrons and are thus weakly dispersed by hydrogen atoms. Protons scatter neutrons strongly therefore neutron diffraction may easily determine protons’ positions.

Neutron Number The number of neutrons in an atom’s nucleus, calculated as the nucleon number (A) minus the proton number (Z).

Nicotinic Acid (Niacin) It is one of the water-soluble B-group vitamins. Pellagra is caused by a lack of it in humans. Nicotinic acid is a component of two coenzymes, NAD and NADP, which act as hydrogen and electron transfer agents and are essential in metabolism.

Ninhydrin It is a colorless chemical molecule that produces a blue color when combined with amino acids. It is used as an amino acid test, specifically to reveal the positions of amino acid spots in paper chromatography.

Nitration A reaction in which the nitro (–NO2) group is introduced into an organic molecule. Aromatic compounds are often nitrated with a mixture of strong nitric and sulfuric acids; however, the exact circumstances vary from compound to compound. NO2+ (the nitryl ion) is the attacking species, and the reaction is an example of electrophilic substitution.

Nitric Acid It is a colorless, fuming, corrosive liquid with a strong acidic nature. In a laboratory, nitric acid can be produced by distilling a mixture of an alkali metal nitrate and concentrated sulfuric acid. Commercially, it is produced through the catalytic oxidation of ammonia and sold as concentrated nitric acid, which contains 68 percent of the acid and is frequently tinted yellow by dissolved nitrogen oxides. Nitric acid is a powerful oxidizer.

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Figure 70. Nitric acid in a container. Source: Image by Wikimedia.

The evolution of nitrogen oxides – the composition of the mixture of the oxides depends on the temperature and on the concentration of the nitric acid used – converts the majority of metals into their nitrates. Some nonmetals, such as Sulphur and phosphorus, react to form oxyacids. Organic compounds (such as sawdust and ethanol) have a violent reaction, but more stable aromatic compounds, such as benzene and toluene, can be transformed to nitro compounds in monitored reactions.

Nitrile It is an organic compound that contains the –CN group. Nitriles are colorless liquids that have pleasant odors. They can be made by refluxing an organic halogen compound with an alcoholic potassium cyanide solution: R+Cl + ^&Œ~€&Œ^&          agent such as phosphorus (V) oxide: RCONH2 – H2|~€&Œ   can be produced by hydrolyzing nitriles. Another reaction that produces amines is hydrogenation: RCN + 2H2~€&}2NH2.

Nitrile Rubber Butadiene-propenonitrile copolymer (acrylonitrile; CH2=CHCN). Because of its resilience to oil and solvents, it is an important form of rubber.

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Nitrobenzene It is yellow organic oil produced by reacting benzene with strong nitric and sulfuric acids. The reaction is a standard electrophilic replacement of the benzene ring by the nitryl ion (NO2+).

Nitro Compound An organic compound with a nitro (–NO2) group linked to an aromatic ring. Nitro compounds can be synthesized through nitration with a solution of strong nitric and sulfuric acids. They can be converted to aromatic amines as follows: RNO2 + 3H2 ~ €Œ}2 + 2H2O. They can also be substituted further on the benzene ring. Substituents are directed into the 3 positions by the nitro group.

Nitrogen `     ' #$5>  *=] an extremely electronegative element that exists in the uncombined state as gaseous diatomic N2 molecules. The electronic arrangement of the nitrogen atom is [He]2s22p3. It is primarily nonmetallic and is mostly held together by polarized covalent bonds. The nitride ion N3– can be produced using electropositive components. It can be found in a wide range of organic compounds, including amines, amides, nitriles, and nitro compounds. Nitrogen has two isotopes: 14N,        > %  #$Œ 5     /"ŽŽ =% which is employed as a label in mass spectrometric research. Symbol: N;  Y/“žŽZ&]  Y#“$žZ&]#$/Ž{Y"5/Z&=] p.n. 7; R.A.M. 14.

Nitrogenous Base It is a basic compound in which a nitrogen atom can take a proton. The term applies to the cyclic ring compounds adenine, guanine, cytosine, thymine, and uracil found in nucleic acids.

Nitro-Glycerine An extremely explosive material used in the manufacture of dynamite. It is made by reacting glycerol (1,2,3-trihydroxypropane) with a strong nitric and sulfuric acid combination. It is a nitrate ester CH2(NO3)CH(NO3)CH2(NO3) rather than a nitro molecule.

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Nitrophenols (C6H4(OH)NO2) Organic compounds generated directly or indirectly as a result of phenol nitration. There are three conceivable isomeric forms. The 2 and 4 isomers are generated through direct phenol nitration and can be separated by steam distillation, with the 2 isomers being steam volatile. The 3 isomer is synthesized from nitrobenzene by forming 1,3-dinitrobenzene, converting it to 3-nitrophenylamine, and then diazotizing it to 3-nitrophenol.

Nonmetal It is any member of a chemical element class. Nonmetals are found in the top right corner of the periodic table. They are electronegative elements that have a propensity to form covalent compounds or negative ions. They contain hydroxides and acidic oxides.

Nonpolar Compound It is a compound comprising molecules that do not have a permanent dipole moment. Nonpolar substances include hydrogen, tetrachloromethane, and carbon dioxide.

Norepinephrine A catecholamine that governs heart muscle, smooth muscle, and glands and it is released as a hormone by the adrenal medulla. It induces arteriole narrowing, which elevates blood pressure. It is also released by sympathetic nervous system nerve endings, where it works as a neurotransmitter. Norepinephrine levels in the brain are linked to mental function and low levels cause mental depression.

Normal Solution It is a solution with one gram of equivalent weight per liter of fluid. The symbol N is used to represent values, such as 0.2N, N/10, and so on. Since there is no precise definition of equivalent weight that is applicable to all reactions, a solution could have one value of normality in one reaction and another value for another reaction. As a result, the molar solution notation is now more commonly used.

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Nuclear Magnetic Resonance (NMR) A technique for studying nuclear spin and in an external magnetic field, the nucleus can have various quantized energy states that relate to different spin magnetic moment orientations. For example, hydrogen nuclei can have two energy states, and transitions between them occur via radiofrequency radiation absorption. This is the foundation of a spectroscopic approach used in chemistry to investigate the structure of molecules. In the fundamental procedure, radiofrequency radiation is applied                ª    the radiation is detected when the difference between the nuclear levels corresponds to absorption of a quantum of radiation. This difference is caused by the electrons surrounding the nucleus, i.e., the atom’s location in the molecule. A chemical shift refers to the difference in frequency of absorption produced by electron distribution.

Nucleic Acids Organic acids have molecules made up of alternating chains of sugar and phosphate units, containing nitrogenous bases connected to the sugar units. They are found in all species’ cells. The sugar in DNA is deoxyribose, while the sugar in RNA is ribose.

Nucleophile It is an electron-rich ion or molecule that participates in an organic process. A nucleophile could be a negative ion (Br–, CN–) or a molecule with a single electron pair (NH3, H2O). The nucleophile targets positively charged regions of molecules caused by the presence of an electronegative atom somewhere else in the molecule.

Nucleophilic Addition It is a type of reaction in which a tiny molecule is added to the double bond of an unsaturated chemical compound. The reaction begins with an attack by a nucleophile, and the unsaturated bond must possess an electronegative atom, resulting in an electron-deficient area in the molecule. Nucleophilic addition is a process common to aldehydes and ketones in which polarization of the C=O carbonyl results in a positive charge on the carbon. This is the point of the nucleophile’s attack. The removal of a distinct tiny molecule, most notably water, frequently succeeds addition.

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Nucleophilic Substitution A reaction in which an atom or group of atoms in an organic molecule is substituted with a nucleophile as the attacking substituent. Nucleophilic substitution happens in compounds where a strongly electronegative atom or group leads to a dipolar bond seeing as nucleophiles are electron rich species. The electron-deficient center is subsequently attacked by the electron-rich nucleophile, displacing the electronegative atom or group. In  %€Y¬ŒY~€YŒ¬Y% ŒY  nucleophile and Le– represents the leaving group.

Nucleoside A nucleoside is a molecule consisting of a pyrimidine or purine base linked to a sugar, either deoxyribose or ribose. The common nucleosides are Adenosine, Cytidine, Guanosine, Thymidine, and Uridine.

Nucleotide The compound is formed by condensation of a nitrogenous base (a purine, pyridine, or pyrimidine) with a sugar (deoxyribose or ribose) and phosphoric acid. The nucleic acids are polynucleotides (consisting of chains of many linked nucleotides), while coenzymes FAD and NAD are dinucleotides (consisting of two linked nucleotides).

Nucleus The compact positively charged center of an atom is made up of one or more nucleons (neutrons and protons) around which there is a cloud of electrons.     #/#${–3. The number of protons in the nucleus, being its proton number or atomic number defines the element. The atomic mass number or nucleon number is the sum of the neutrons and protons. The simplest nucleus is that of a hydrogen atom, 1H, being simply one proton (mass 1.67 × 10–27 kg). The most massive naturally occurring nucleus is 238U of 92 protons and 146 protons (mass 4 × 10Y$ {%   “$‰ ´ #/Y#$ m). Only a few combinations of neutrons and protons form stable nuclei and others undergo spontaneous decay. A nucleus is typically shown by a symbol indicating proton number (atomic number), element name, and nucleon number (mass number). For, e.g., 1123Na represents a nucleus of sodium having mass 23 and 11 protons, hence there are (23 – 11) = 12 neutrons.

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Nuclide A nuclide is a nuclear species with a given number of neutrons and protons. For, e.g., 24Mg, 23Na, and 24Na are all different nuclides. Thus: 2411Na has 13 neutrons and 11 protons, 2311Na has 12 neutrons and 11 protons, and 2411Mg has 12 neutrons and 12 protons. The term has often applied to the atom and also to the nucleus.

Nylon Nylon is a type of synthetic polymer linked by amide groups –NH.CO–. Nylon polymers can be made by copolymerization of a molecule containing two amine groups with one containing two carboxylic acid groups.

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O Occlusion Occlusion is the process in which small amounts of one substance are trapped in the crystals of another. For example, pockets of liquid occluded during crystallization from a solution.

Octadecanoic Acid Octadecanoic acid is a solid carboxylic acid present in oils and fats as glyceride. Octadecenoic acid is a naturally occurring unsaturated carboxylic acid present in oils and fats as glyceride: CH3(CH2)7CH: CH(CH2)7COOH. The naturally occurring form is cis-9-octadecenoic acid.

Octane Octane is a liquid alkane, obtained from a light fraction of crude oil. The principal constituents of gasoline are octane and its isomers, which are obtained as the refined light fraction from crude oil.

Octane Rating Octane rating is a rating for the performance of gasoline in internal combustion engines. The octane rating estimates the freedom from ‘knocking’ i.e., preignition of the fuel in the engine. This depends on the relative proportions of straight-chain hydrocarbons and branched-chain present. In highperformance engines, high proportions of branched-chain alkanes are better. In rating fuels, 2,2,4-trimethylpentane (isooctane) is given a value of 100, and heptane is given a value of 0. The performance of fuel is contrasted with a mixture of these hydrocarbons.

Octet Octet is a stable shell of eight electrons in an atom. This is the basis of the Lewis octet theory and the completion of the octet gives rise to particular stability and, thus: š š

The rare gases are chemically inert and have complete octets. The bonding in small covalent molecules is often achieved by the central atom completing its octet by sharing electrons with surrounding atoms, e.g., H2O, CH4.

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181

The ions formed by electronegative and electropositive elements are usually those with a complete octet, e.g., O2–, Na+, Cl–, Ca2+.

Ohm Ohm is the SI unit of electrical resistance, which is equal to a resistance that passes a current of one ampere when there is an electric potential difference

 >   #¶#*Y#˜ % ?   the resistance of a column of mercury under defined conditions. The unit is    ©  © | 5#!ž!Y#ž$‰=

Oil Oil is any of various viscous liquids. Mineral oils are usually mixtures of hydrocarbons. Natural oils, excreted by animals and plants are glycerides of fatty acids or are either mixtures of terpenes and esters.

Oil Shale |    {  "/YŽ/”  organic matter, predominantly in the form of bitumen. It produces an oily substance resembling petroleum when heated in the absence of air, which is rich in sulfur and nitrogen compounds.

Oligomer The oligomer is a polymer formed from relatively few monomer molecules.

Oligosaccharide Oligosaccharide is a carbohydrate formed of a small number of monosaccharide units which is usually up to around 20.

One-Pot Synthesis One-pot synthesis is a synthesis of a chemical compound in which the reactants form the needed product in a single reaction mixture.

Onium Ion Onium ion is an ion formed by the addition of a proton (H+) to a molecule. The examples are hydronium (or hydroxonium) ions (H3O+) and ammonium ions (NH4+).

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Optical Activity When the light is passed through certain compounds, the ability of these compounds to rotate the plane of polarization of plane-polarized light is known as optical activity. Optical activity can be seen in solutions, gases, crystals, and liquids. The concentration of the active compound determines the amount of rotation. Optical activity is induced by the interaction of the varying electric field of light with the electrons in the molecule. It happens when the molecules have no plane of symmetry or they are asymmetric. Such molecules have a mirror image that can’t be superposed on the original molecule. The two forms of the molecule are enantiomers or optical isomers. (Stereoisomers that are not mirror images of each other are {     =`       that the molecule contains a carbon atom attached to four different groups, and thus forming a chiral center

Optical Rotary Dispersion (ORD) Optical rotary dispersion (ORD) is the phenomenon in which the wavelength of the light determines the amount of rotation of plane-polarized light by an optically active substance. Plots of rotation against wavelength can be utilized to provide information about the molecular structure of optically active compounds.

Optical Rotation Optical rotation is the rotation of the plane of polarization of plane-polarized light by an optically active substance.

Orbital Orbital is a region around an atomic nucleus in which there is a high chance of detecting an electron. The modern picture of the atom according to quantum mechanics does not have electrons moving in fixed elliptical orbits. Rather, there is a precise probability that the electron will be found in any small region at all possible distances from the nucleus. In the hydrogen atom, near the nucleus, the probability is low, increases to a maximum, and falls off to infinity. It is helpful to think about an area in space around the nucleus, in the case of hydrogen the region within a sphere, inside which there is a high probability of locating the electron. Each of these, called an atomic orbital,

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relates to a subshell and can ‘contain’ two electrons or a single electron with opposite spins. Another method of picturing an orbital is as a cloud of electron charge (the average distribution with time).

Order The sum of the indices of the concentration terms in the expression determines the rate of a chemical reaction. For example, in the expression: rate = k[A] x[B]y x is called the order with respect to A, y the order with respect to B, and (x + y) the order overall. The values of x and y are not: CH3&}|~&}4 + CO the rate is proportional to [CH3&}|³#$%%  #$

Organic Acid Organic acid is an organic compound that can release hydrogen ions (H+) to a base, such as phenol or carboxylic acid.

Organic Base An organic base is an organic compound that can function as a base. Organic bases are usually amines that gain H+ ions.

Organic Chemistry Organic chemistry is the branch of chemistry that studies the chemistry of compounds of carbon. Initially, the term organic chemical alluded to chemical compounds present in living matter, yet presently it covers any carbon compound except for certain basic ones, like cyanates, carbon oxides, cyanides, and carbonates. These are usually studied in inorganic chemistry. The tremendous quantities of synthetic and natural organic compounds exist in light of the ability of carbon to form chains of atoms (catenation). Other components are involved in organic compounds, primarily oxygen and hydrogen yet in addition phosphorus, nitrogen, sulfur, and halogens.

Organometallic Compound An organometallic compound is an organic compound containing a carbonmetal bond. Tetraethyl lead, (C2H$)4Pb, is an example of an organometallic compound, and it was formerly utilized as an additive in petrol.

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Ornithine Cycle Ornithine cycle is the sequence of enzyme-controlled reactions by which as a breakdown product of amino acids, urea is formed. It occurs in cells of the liver. The amino acid ornithine is combined with carbon dioxide and ammonia (from amino acids), forming another amino acid, arginine, which is then split into ornithine and urea (which is excreted).

Ortho Designating a benzene compound with substituents in the 1,2 positions. The position next to a substituent is the ortho position on the benzene ring. This was utilized in the systematic naming of benzene derivatives. For instance, orthodinitrobenzene (or o-dinitrobenzene) is 1,2-dinitrobenzene. Certain acids, regarded as formed from water and an anhydride, were named ortho acids to separate them from the less hydrated meta acids. For instance, H4SiO4 (from SiO2 + 2H2O) is orthosilicic corrosive and H2SiO3 (SiO2 + H2O) is metasilicic corrosive. Designating the form of a diatomic molecule in which the two nuclei have the same spin direction, for example, orthodeuterium and orthohydrogen.

Osmium (IV) Oxide It (osmium tetroxide; OsO4) is a volatile yellow crystalline solid with a penetrating odor, utilized in an aqueous solution, as a catalyst for organic reactions and as an oxidizing agent.

Osmosis Osmosis is a system in which a solvent is segregated from a solution by semipermeable membrane approach equilibrium by solvent molecules on the solvent side of the membrane migrating through it to the solution side. This always leads to dilution of the solution and the process is called osmosis. The phenomenon is quantified by the measurement of the osmotic pressure. The process of osmosis is of essential significance in transport and control mechanisms in biological systems. For instance, general cell function and plant growth.

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Figure 71. Osmosis. Source: Image by Wikimedia.

Osmotic Pressure It refers to the pressure that must be applied to a solution for preventing the passage of solvent molecules into it when the solution and solvent are segregated by a semipermeable membrane. The osmotic pressure is thus, the pressure needed to maintain equilibrium between the passage of solvent molecules through the membrane in either direction and thus prevent the process of osmosis proceeding. The osmotic pressure can be calculated by placing the solution, contained in a small perforated thimble covered by a semipermeable membrane and       %  {   >Q > molecules pass through the membrane and dilute the solution and as a result, increase the volume on the solution side and force the solution to rise up the  Q ¨

Oxaloacetic Acid (OAA) Oxaloacetic acid (OAA) is a water-soluble carboxylic acid, structurally related to maleic acid and fumaric acid. Oxaloacetic acid forms part of the Krebs cycle. It is produced from L-malate in a NAD requiring reaction and itself is a step towards the formation of citric acid in a reaction involving coenzyme A and pyruvate ions.

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Oxidant An oxidant is an oxidizing agent. In rocket fuels, for combustion, the oxidant is the substance that provides oxygen (for example, hydrogen peroxide or liquid oxygen).

Oxidative Phosphorylation The productions of ATP from phosphate and ADP as electrons are transferred along the electron-transport chain from FADH2 or NADH to oxygen. Most of the FADH2 and NADH are formed in the mitochondrial matrix by the fatty acid oxidation and the Krebs cycle. Oxidative phosphorylation occurs in mitochondria and is the primary source of ATP in aerobic.

Oxidation A molecule, an atom, or an ion, is said to be oxidized or to undergo oxidation when it loses electrons. The process may be affected electrically, in which case oxidation occurs at the anode or chemically, i.e., by reaction with an oxidizing agent. For, e.g., 4CNР+ 2Cu2+~&2N2 + 2CuCN where Cu2+ is the oxidizing agent and CNРis oxidized and 2Na + Cl2~Π+ + 2ClРwhere chlorine is the oxidizing agent and sodium is oxidized. The oxidation state of an atom is specified by the number of electrons lost or effectively lost by the neutral atom, i.e., the oxidation number. The oxidation number of a negative ion is negative. The process of oxidation is the reverse of reduction.

Oxime Oxime is a type of organic compound containing the C: NOH group, formed by the reaction of ketone or an aldehyde with hydroxylamine (NH2OH). The reaction is a condensation reaction, in which a molecule of water is lost.

Oxo Process The Oxo process is a method of manufacturing aldehydes by passing a mixture of alkanes, carbon monoxide, and hydrogen over a cobalt catalyst   5#$/Z& #//   =      course be reduced to alcohols, making the process a useful source of alcohols of high molecular weight.

Oxyacid Oxyacid is an acid in which the replaceable hydrogen atom is part of a hydroxyl group, including phenols, carboxylic acids, and inorganic acids such as sulfuric(VI) acid and phosphoric(V) acid.

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Oxygen Oxygen is an odorless and colorless diatomic gas and it is the first member of group 16 (formerly VIA) of the periodic table. Its chemistry involves the acquisition of electrons to form either the two covalent bonds or di-negative ion, O2–, and it has the electronic configuration [He]2s22p4. In each case, the oxygen atom attains the configuration of the rare gas neon. Oxygen is the most abundant element in the Earth’s crust accounting   > ‰/”    `         5/”=    constituent of the majority of rocks and minerals (e.g., aluminosilicates, sandstones, CaCO3, SiO2, carbonates) and it is the major constituent of the sea as well. For almost all living things, oxygen is an essential element. Elemental oxygen has two forms: the less stable molecule trioxygen (ozone), O3, and the diatomic molecule O2, which is formed by passing an electric discharge through oxygen gas. Oxygen occurs in three natural isotopic forms, 16| 5““!Ž”=% 17| 5//"!‰”=% 18| 5//"“”=]     isotopes are utilized in detailed studies of the behavior of oxygen-containing    5 =Q |]Y#ž‰Z&] Y#ž“ŽZ&]#‰“{–35/Z&=]ž] #$“““‰

Ozone (Trioxygen; O3) It is a blue-colored and poisonous allotrope of oxygen made by passing oxygen through a silent electric discharge. Ozone decomposes to oxygen on warming and is unstable. It is a strong oxidizing agent. It is present in the upper layers of the atmosphere, and it protects the Earth from harmful short-wave ultraviolet radiation. There is concern that the ozone layer is possibly being depleted by fluorocarbons and other compounds produced by industry.

Ozonolysis The addition of ozone (O3) to alkenes and the subsequent hydrolysis of the ozonide into hydrogen peroxide and a mixture of carbonyl compounds. The carbonyl compounds can be identified and separated, which as a result, identifies the groups and locates the position of the double bond in the original alkene. Formerly, ozonolysis was a significant analytical technique.

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P Pantothenic Acid     %   {   >  ‚$      \  B-group of vitamins. Egg yolk, kidney, liver, and yeast are included in the sources of the vitamin. As a component of coenzyme, A, pantothenic acid is vital for various fundamental reactions in metabolism. An insufficiency results in symptoms affecting a wide variety of tissues, the overall impacts include muscle cramps, fatigue, and poor motor coordination.

Paper Chromatography Paper chromatography is a form of chromatography that is widely utilized for the analysis of mixtures. As the stationary phase, paper chromatography generally employs specially produced paper. Near the bottom of the paper, a baseline is marked in pencil, and using a capillary tube a small sample of the mixture is spotted onto it. The paper is then placed vertically in a suitable solvent, which by capillary action rises up to the baseline and beyond. In this mobile phase, the components within the sample mixture dissolve and are carried up the paper. Although, the paper holds a quantity of moisture and few components will have a greater tendency than others to dissolve in this moisture as opposed to in the mobile phase. Additionally, few components will preferentially hold on to the surface of the paper. Therefore, as the solvent moves through the paper, components in the mixture will become separated from each other as certain components will be left behind.

Partial Ionic Character The electrons of a covalent bond between atoms or groups with different electronegativities will be polarized towards the more electronegative constituent. By the ionic character of the bond, the magnitude of this effect can be measured. When the effect is small the bond is alluded to simply as a polar bond and using dipole moments is adequately treated, as the effect widens the theoretical treatment and requires various other contributions to an ionic character.

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Partial Pressure Partial pressure refers to the contribution that one component makes to the total pressure in a mixture of gases. It is the pressure that the gas would have if it alone were available in the same volume.

Particulate Matter (PM) Particulate matter is an airborne pollutant consisting of small particles of carbon, silicate, or large polyaromatic hydrocarbons (PAHs). These pollutants are usually alluded to as particulates. They are categorized according to size, for example, PM10 is particulate matter formed of particles less than 10 μm diameter.

     If a solute dissolves in two non-miscible liquids, the partition coefficient is the equilibrium ratio of the concentration in one liquid to the concentration in the other liquid.

Pascal Symbol Pascal symbol is the SI unit of pressure, equal to a pressure of one newton per square meter (1 Pa = 1 N m–2). The unit is named after the French mathematician Blaise Pascal (1623–62).

Pectic Substances Pectic substances are polysaccharides that, along with hemicelluloses, form the matrix of plant cell walls. They serve to cement the cellulose fibers together. A rich source is fruits. They are mainly made from the group of sugar acids also known as uronic acids. Pectic acids, which are the basis of     %       

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of the fact that there was a distinction in usage for subgroups and a present form of the table has 18 groups.

Figure 72. Periodic Table. Source: Image by Wikimedia.

Peroxide Peroxide is a compound containing the –O–O– group. Organic peroxides form free radicals and tend to be unstable. They are utilized to begin freeradical polymerization reactions. It is an oxide containing the –O–O– ion.

Petroleum Petroleum is a mixture of hydrocarbons, which is originally formed from marine plants and animals, found underneath the ground enmeshed between the layers of rock. It is also called crude oil and is obtained by drilling. Various oilfields produce petroleum with varying compositions. The mixture is segregated into fractions by fractional distillation in a vertical column. The principal fractions are Diesel oil, also known as gas oil in the range /Y"$/Z&%    &#"Y&$    `%      ^     {           #Ž/Y $/Z&%    &# &##     `       for jet engines and domestic heating. Gasoline is also known as petrol in the  ‰/Y#ž/Z&%   &$Y&#/    `[ as a raw material for making other chemicals and as motor fuel.

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Petroleum Ether Petroleum ether is a flammable mixture of hydrocarbons, mainly hexane and pentane, utilized as a solvent.

pH It is refers to the logarithm to base 10 of the reciprocals of the hydrogen        `  $Z&%      hydrogen ions is 1.00 × 10–7 mol l–1, therefore at neutrality, the pH equals 7. The value of [H+] is increased by an increase in acidity, which in turn decreases the value of the pH below 7. An increase in the concentration of hydroxide ion [OH–] proportionately decreases [H+], thus, in basic solutions increasing the value of the pH above 7. pH values can be acquired approximately by utilizing indicators. More accurate measurements utilize electrode systems. The term ‘pH’ is an abbreviation for ‘potential of hydrogen.’

Phase It is one of the physically separable parts of a chemical system. For example, water (liquid phase) and a mixture of ice (solid phase) consist of two phases. Homogeneous is referred to as a system consisting of only one phase. Heterogeneous is referred to as a system consisting of more than one phase.

Phase Diagram The phase diagram is a graphical representation of the state in which a substance will occur at a given temperature and pressure. The lines demonstrate the circumstances under which more than one phase can coexist at equilibrium. For one-component systems, for, e.g., water, the triple point is referred to the point at which all three phases can coexist at equilibrium and is the point on the graph at which the pressure-temperature curves intersect.

Phenol A white crystalline solid is utilized to make a variety of various other organic compounds. It is generally made using the Raschig process or the Cumene process (Carboxylic acid; hydroxybenzene; C6H$OH). A type of organic compound in which at least one hydroxyl group is bound directly to one of the carbon atoms of an aromatic ring. Phenols do not demonstrate the behavior typical of alcohol. Particularly, they are more acidic in light of the electron-withdrawing effect of the aromatic ring. Phenol ionizes in water:

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C6H$|}~&6H$OР+ H+ The formulation of phenol itself is by combining the sodium salt of the sulfonic acid with sodium hydroxide: C6H$SO2.ONa + Π|}~&6H$ONa + Na2SO3 + H2O.

Phenolphthalein Phenolphthalein is an acid-base indicator that becomes red if the pH rises above the transition range of 8–9.6 and is colorless in acid solutions. It is utilized as the indicator in titrations for which the endpoint lies clearly on the basic side (pH > 7), for example, oxalic acid or potassium hydrogen tartrate against caustic soda.

Phenylethene (Styrene; C6H5CHCH2) A liquid hydrocarbon is utilized as the starting material for the production of some synthetic rubbers and polystyrene. The production of phenylethene is by dehydrogenation of ethylbenzene utilizing many metal oxide catalysts: C6H$C2H$~&6H$CH:CH2 + H2

Phenylmethanol Phenylmethanol is an aromatic primary alcohol utilized as a solvent. Phenylmethanol is synthesized by the CANNIZZARO REACTION, which includes the simultaneous oxidation and reduction of benzene carbaldehyde (benzaldehyde) by refluxing in an aqueous solution of sodium hydroxide: 2C6H$&}| ~ &6H$CH2OH + C6H$COOH. Benzoic acid is the other product. Phenylmethanol goes through the reaction’s characteristic of alcohols, particularly those in which the formation of a stable carbonium ion as an intermediate (C6H$CH2 +) improves the reaction. Substitution onto the benzene ring is also possible; the –CH2OH group directs into the 2- or 4-position by the donation of electrons to the ring.

Phenyl Methyl Ketone Phenyl methyl ketone     /Z&         \ smelling organic liquid. It is utilized as a solvent for methyl and ethyl cellulose plastics.

Phenylpropenoic Acid (Cinnamic Acid) Phenylpropenoic acid is a white pleasant-smelling crystalline carboxylic acid, C6H$CH:CHCOOH. It occurs in amber but can be synthesized and is utilized in flavorings and perfumes.

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Pheromone Pheromone is a substance that is discharged by an animal and causes a reaction in various other animals of the same species (for, e.g., sexual attraction, development).

Phillips’s Process Phillips’s process is a method for the manufacturing of high-density polyethene utilizing a catalyst of chromium(III) oxide on a promoter of          "/  #$/Z&

Phosphate Phosphate is a salt or ester of a phosphorus(V) oxoacid, mainly one of phosphoric(V) acid, H3PO4. Polymeric phosphates occur containing P–O–P bridges.

Phosphine Phosphine is slightly soluble in water and is a colorless gas. It has a characteristic fishy smell. It can be made by the action of yellow phosphorus on a concentrated alkali or by reacting calcium phosphide and water. Phosphine generally ignites spontaneously in the air due to contamination with diphosphine.

Phospholipid A phospholipid is a lipid with a phosphate group attached by an ester linkage. They are the major class of lipids in all biological membranes and, together with cholesterol and glycolipids, are the primary structural components. All membrane phospholipids, except sphingosine, are called glycerophospholipids as they are derived from glycerol. They consist of a glycerol backbone with two fatty acid chains esterified to carbons 1 and 2 and phosphorylated alcohol esterified at carbon The simplest glycerophospholipid is phosphatidate or diacylglycerol 3-phosphate, which has no alcohol part. Naturally, only small amounts exist, but it is a vital intermediate in the biosynthesis of other glycerophospholipids                >   

 (glycerol, serine, choline, or ethanolamine) to form the major membrane glycerophospholipids: phosphatidylglycerol, phosphatidylserine, phosphatidylcholine, and phosphatidylethanolamine. Sphingomyelin (like

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glycolipids) is derived from sphingosine and has a phosphorylcholine      ?    

Phosphonic Acid (Phosphorous Acid; H3PO3) A deliquescent solid which has no color, that can be prepared by the action of water on phosphorus(III) chloride or phosphorus(III) oxide. It is a dibasic acid, producing the anions H2PO3– and HPO32– in water. The acid and its salts are slow-reducing agents.

Phosphoric (V) Acid Phosphoric acid is a white solid that can be made by heating yellow phosphorus with nitric acid or by reacting phosphorus(V) oxide with water. The phosphates which occur naturally (orthophosphates, M3PO4) are salts of phosphoric(V) acid.

Phosphorescence It is the assimilation of energy by atoms followed by the emission of electromagnetic radiation. Phosphorescence is distinguished from fluorescence by the fact that the emitted radiation continues for some time after the source of excitation has been removed and it is a type of luminescence. In phosphorescence, before the excited atoms make transitions to lower energy states, they have relatively long lifetimes although there is no defined time distinguishing phosphorescence from fluorescence. In general usage, the term is applied to the emission of ‘cold light’ – light generated without a high temperature. The name comes from the fact that as a result of a chemical reaction with oxygen, white phosphorus glows slightly in the dark. The light comes from excited atoms produced directly in the reaction and not from the heat produced. It is therefore an example of chemiluminescence. Additionally, there are numerous biochemical examples termed bioluminescence, for, e.g., phosphorescence is sometimes   

  5{  ’ ?'=    from marine organisms.

Phosphorus Phosphorus is a reactive solid nonmetallic element and it is the second  #$5 *=    . It is formally similar to nitrogen and it has the electronic configuration [Ne]3s23p3. However, it is

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never found in nature in the uncombined state and very much more reactive than nitrogen. Throughout the world, Phosphorus is widespread, economic sources are the apatites and phosphate rock (Ca3(PO4)2), variously occurring as both chloroapatite (3Ca3(PO4)2CaCl2) and fluoroapatite (3Ca3(PO4)2.CaF2). Also, an important source of phosphorus is guano formed from the skeletal phosphate of fish in sea-bird droppings. The largest amounts of phosphorus compounds produced are utilized as fertilizers, with the detergents industry producing increasingly large tonnages of phosphates. Phosphorus is a vital constituent of bones and living tissue, and it           _ without any color is made by reacting phosphorus with bromine. It is readily hydrolyzed by water to hydrogen bromide and phosphonic acid.   5```=     %[ to replace a hydroxyl group with a bromine atom. A yellow crystalline solid that sublimes easily and can be made by the reaction of bromine and phosphorus(III) bromide. Phosphorus(V) bromide is readily hydrolyzed by water to phosphoric(V) acid and hydrogen bromide. Its primary utilization in organic chemistry is to replace a hydroxyl group with a bromine atom.

Phosphorus (III) Chloride A liquid without any color, formed from the reaction of phosphorus with chlorine. It is hastily hydrolyzed by water to hydrogen chloride and phosphonic acid. In organic chemistry, Phosphorus(III) chloride is utilized to replace a hydroxyl group with a chlorine atom.

Phosphorus(V) Chloride It is a white easily sublimed solid formed by the action of chlorine on phosphorus(III) chloride. It is hydrolyzed by water to phosphoric(V) acid and hydrogen chloride. Its main use is as a chlorinating agent in organic chemistry to replace a hydroxyl group with a chlorine atom.

Phosphorus (III) Chloride Oxide (Phosphorus trichloride oxide; phosphorus oxychloride, phosphoryl chloride, POCl3). A colorless liquid that can be obtained by distilling phosphorus(III) chloride with potassium chlorate or by reacting phosphorus(III) chloride

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with oxygen. The reactions of phosphorus(III) chloride oxide are similar to those of phosphorus(III) chloride. The chlorine atoms can be replaced by alkyl groups utilizing Grignard reagents or by alkoxo groups using alcohols. Water hydrolysis yields phosphoric(V) acid.

Phosphorus(V) Oxide Phosphorus(V) oxide is a white powder that is soluble in organic solvents. It generally exists as P4O10 molecules. Phosphorus(V) oxide can be produced by burning phosphorus in an abundant supply of oxygen. It is used as a drying agent for gases as it readily combines with water to form phosphoric(V) acid. It is a useful dehydrating agent in light of the fact that it is able to remove the elements of water from compounds containing hydrogen and oxygen.

Phosphorylation The transfer of a phosphoryl group –PO(OH)2 from ATP to a protein by a protein kinase. Various metabolic enzymes are regulated by phosphorylation as numerous signal pathways are involved in cell growth. The removal of the phosphoryl group (dephosphorylation) is brought about by enzymes known as phosphatases.

Photochemical Reaction A reaction brought about by ultraviolet radiation or light, examples include the photosynthesis of carbohydrates, the reduction of silver halides (in photography), and the bleaching of colored material. Chemical changes occur only when the photons have sufficient energy to produce free radicals or ions or when the reacting atoms or molecules absorb photons of the appropriate energy to produce excited species. The amount of substance that reacts is proportional to the quantity of energy absorbed. For example, in the reaction between chlorine and hydrogen, it is not the concentrations of chlorine or hydrogen that dictates the rate of reaction but it is the intensity of the radiation.

Photoionization It is the ionization of atoms or molecules by electromagnetic radiation. Photons absorbed by an atom might have sufficient photon energy to free an          >~ e– As in the photoelectric effect, the radiation must have a certain minimum

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threshold frequency. The energy of the photoelectrons ejected is given by W = hv – I, where I is the ionization potential of the molecule or atom. Analysis of the energies of the emitted electrons provides information on the ionization potentials of the substance, a technique known as photoelectron spectroscopy.

Photolysis Photolysis is a chemical reaction that is produced by electromagnetic radiation (ultraviolet radiation or light). Various photolytic reactions involve the formation of free radicals.

Photosynthesis It refers to the synthesis of organic compounds utilizing light energy absorbed by chlorophyll. With the exception of a small group of bacteria, organisms photosynthesize from inorganic materials. All green plants as well as certain prokaryotes (some bacteria) photosynthesize. In green plants, photosynthesis takes place in chloroplasts, mainly in leaves. Directly or indirectly, photosynthesis is the source of energy and carbon for all except chemoautotrophic organisms. The mechanism involves two sets of stages and is complex: light reactions followed by dark reactions. The overall reaction in green plants can be summarized.

Photosynthetic Pigments Photosynthetic pigments are the pigments which absorb the solar energy that is required in the process of photosynthesis. These pigments are situated in the chloroplasts of the algae and plants, whereas in most of the photosynthetic bacteria they are situated in the thylakoid membranes, usually distributed around the periphery of the cells. Generally, all the photosynthetic organisms consist of the carotenoids and chlorophylls. Out of which some are also consisting of phycobilins. Chlorophyll A plays the major role as primary pigment, as the energy being absorbed by this is utilized directly in order to drive the light reactions of photosynthesis. The chlorophyll A that forms the reaction center of photosystem II has an absorption peak at 680 nm and that of photosystem I at about 700nm. Apart from this, the other pigments such as chlorophylls B, C, and d, along with the carotenoids and phycobilin; plays an important role as additional pigments that assist in passing the energy that they absorb onto chlorophyll A.

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Phycobilin Phycobilin is a group of additional pigments in the process of photosynthesis and is found in red algae and Cyanobacteria. Phycobilins are chemically linear tetrapyrroles with respect to the chlorophyll, which is a cyclic tetrapyrrole. Phycobilin absorbs the light in the middle of the spectrum which is not being absorbed by the chlorophyll, and also plays a significant role in algae that are thriving under water where blue and red light is being absorbed in the surface layers. These are composed of blue phycocyanins, and they absorb the extra red light along with the orange light. On the other hand, the red phycoerythrins absorb the green light, and hence it enables the red algae in order to grow at depth in the sea.

Physical Change Physical change is the change to a body or a substance that does not change the chemical properties of that substance or body. Comparatively, the physical changes are much easier to reverse (such as melting, boiling, and dissolving).

Physical Chemistry Physical chemistry is the branch of chemistry that deals with the physical properties of the compounds and also, how they rely on the chemical bonding. Physical chemistry consists of various topics such as chemical thermodynamics and electrochemistry.

Picric Acid Picric acid is a yellow crystalline solid which is made up with the help of nitrating phenol sulfonic acid. Picric acid is utilized in the form of a dye and in the form of an explosive. With the combination of aromatic hydrocarbons, picric acid forms a characteristic charge – transfer complexes that have been used in the analysis in order to identify the hydrocarbons.

Pipette Pipette is a device which is being used in order to transfer a known volume of a solution from one container to the other container. Generally, various samples of equal volume are transferred for individual analysis from one

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stock solution. There are two types of pipettes that have been found, first is bulb pipette, and second type is graduated pipettes. ‚    {   ?> |  other hand, graduated pipettes are used to transfer variable volumes. Pipettes were at one time universally mouth – operated but safety pipettes with the help of a plunger or rubber bulb are now preferred.

Figure 73. Water pipette. Source: Image by Pixabay.

Planck Constant Plank constant is a fundamental constant, and it is the ratio of the energy (W) which is carried with the help of a photon to its frequency (v). There is a basic relationship in the quantum theory of radiation which states W = hv. Where, the value of h = 6.626 196 × 10–34 J s. The plank constant appears in several various equations in which some observable measurement is quan[ 5  %     {    >          other ranges of value).

Plane Polarization Plane polarization is a type of polarization of electromagnetic radiation in which the vibrations occur completely in one place.

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Plant Hormone Plant hormone plays an important role in essential substances that are produced in the plants. Plant hormones are very effective in considerably low concentrations and control growth and development by their interactions. Various examples of plant hormones are auxins, ethylene, abscisic acid, gibberellins, and cytokinins.

Plastic Plastic is a substance that can be turned into any shape with the help of applying heat and pressure. Most plastics are made up with the help of synthetic compounds known as polymers. Nevertheless, some plastic is made with the help of natural material like cellulose.

Platinum Platinum is a malleable ductile transition metal and it is silvery – white in color. Platinum is naturally found in Australia and Canada, either free or in association with the other platinum metals. Platinum is immune to oxidation and it is not attacked by any form of acids (apart from aqua regia or alkalis). The metal, platinum, is used in the form of a catalyst for ammonia oxidation (in order to make nitric acid), hydrocarbon cracking, and in the catalytic converters. Platinum is also used in making jewelry.

Platinum Black Platinum is a finely divided black form of bi-product of platinum, as a coating. Platinum black is obtained by evaporating platinum onto a surface in an inert atmosphere. The coatings of platinum – black are being used in the form of absorbents and in the form of catalysts as well.

Poison Poison is a substance that destroys the activity of a catalyst. Poison is any substance that threatens biological activity, whether by physical means or chemical means.

Polar Polar is a term which is used in order to describe a compound with the molecules that have a permanent dipole moment. Some examples of polar compounds are hydrogen chloride and water.

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Polar Bond Polar bond is a covalent bond in which the bonding electrons are not shared between the two atoms equally. A bond between the two atoms having different electronegativity is said to be polarized in the direction of the more electronegative atom, that is, the electrons are drawn particularly in the direction of the atom.

Polarization Polarization is usually the restriction of the vibrations in a transverse wave, in such a way that the vibrations will take place in a single plane. For example, electromagnetic radiation is a transverse wave motion. Electromagnetic radiation can be considered in the form of an oscillating electric field and an oscillating magnetic field, both at right angles to the direction of propagation and at right angles with respect to each other. © %    >             interacts with the charged particles of the matter, and produces the effect. In   ? ’  '  [   %    all possible directions which is at right angle to the direction of the wave.

Polar Molecule It is a molecule in which the individual polar bonds are not exactly symmetrically arranged and so are not ‘in balance.’ Thus, charge separation in the bonds results in total charge separation in the molecule, as seen in water. These molecules have a dipole moment.

Polarography An analytical technique that measures current as a function of potential. A unique cell is used, with a small easily polarizable cathode (the dropping mercury electrode) and a large non-polarizable anode (reference cell). The analytical reaction occurs at the cathode and is mostly a reduction of the cations, which are discharged in the order of their electrode potential values. The data is shown as a polarogram, which is a plot of current vs. applied voltage. The ion is discharged as the applied potential increases. The current increases stepwise before levelling off due to polarization effects. The halfwave potential (the potential at half the step height) is utilized to identify the ion. Polarography can determine the majority of elements. The optimum

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concentrations are in the 10–2–10–4   ]    _   measurements in the parts per million level.

Pollution It refers to any undesirable or harmful alteration in the environment caused by the physical, chemical, or biological byproducts of human industrial or social activity. Pollution can have an impact on the atmosphere, rivers, seas, and soil. Domestic and industrial combustion of carbonaceous fuels, industrial operations, and car exhausts all contribute to air pollution. Recent issues include industrial emissions of sulfur(IV) oxide, which    %            ˆ    % which are used in refrigeration, aerosols, and other products, and have been related to stratospheric ozone depletion. Carbon dioxide, which is produced by burning fuel and by car exhausts, is steadily accumulating in the atmosphere, which may result in an overall increase in the temperature of the atmosphere (greenhouse effect). Carbon monoxide and lead are also found in car exhaust.

Polyamine A compound with two or more amino and/or amino groups that is aliphatic in nature. Polyamines are frequently discovered in bacteria and viruses in association with DNA and RNA. This may act to stabilize the nucleic acid molecule in a manner similar to how histones act on DNA in eukaryotic cells. Spermine, spermidine, cadaverine, and putrescine are examples of polyamines.

Polycarbonate A thermoplastic polymer composed of carbonic acid polyesters and dihydroxy compounds. Polycarbonates are durable and transparent plastics that are used to make soft drink bottles and electrical connectors.

Polychlorinated Biphenyl (PCB) It is a biphenyl (C6H$C6H$)-based molecule in which part of the hydrogen atoms have been replaced with chlorine atoms. They are found in certain polymers that are used to make electrical insulators. PCBs are highly hazardous, and their ability to accumulate in the food chain has raised concerns.

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Polyester A synthetic polymer created by reacting alcohols with acids, resulting in monomers connected by the –O–CO– group. Polyesters include synthetic fibers such as Dacron.

Polyethene (Polyethylene; Polythene) A synthetic polymer derived from ethene. It comes in two varieties: a soft, low-density material and a tougher, higher-density, more rigid version. The Ziegler process and the Phillips process can be used to create it.

Polymer A compound containing very large molecules composed of repeating molecular units (monomers). A polymer has a repetitive structural unit known as a mer. Because the lengths of distinct chains vary, polymers do not usually have a precise relative molecular mass. They can be natural (for example, polysaccharides and proteins) or manufactured (e.g., nylon and polyethene). The thermosetting (e.g., Bakelite) and thermoplastic (e.g., polyethene) families of synthetic polymers are the most common. The former is infusible and will only become harder when heated, whereas the latter will soften when heated.

Polymerization It is the reaction of one or more chemicals to generate a polymer. Polymerization of one monomer results in the creation of homopolymers (e.g., the formation of polyethene). Heteropolymers or copolymers are made up of two or more monomers (as for nylon). Depending on how the units are arranged, heteropolymers can be of many sorts. An arrangement exists in an alternating copolymer of two units A and B. These are tactic polymers. The polymer is considered to be isotactic if one of its groups is always on the same side of the chain. The polymer is syndiotactic if the group alternates in position along the chain. The polymer is atactic if there is no regular pattern.

Polypropene (Polypropylene) A propene-based synthetic polymer and has qualities similar to polyethene but is stronger and lighter. The Ziegler technique is used to polymerize propene.

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Polysaccharide It refers to a monosaccharide polymer with a high molecular weight. Polysaccharides have a lot of repeating units in their molecular structures. Hydrolysis or the proper enzyme can be used to break them down into smaller polysaccharides, disaccharides, and monosaccharides. Heparin, inulin, starch, glycogen (also known as animal starch), and cellulose are all important polysaccharides.

Polystyrene It is a styrene-based synthetic polymer (phenylethene). Expanded polystyrene is stiff foam that is commonly used in packaging and insulation.

  * +"# A tetrafluoroethene-based synthetic polymer (i.e., CF2:CF2). It can resist high temperatures without decomposing and has a very low coefficient of friction, making it useful in nonstick pans, bearings, and other applications.

Polyurethane It refers to a synthetic polymer containing the group –NH–CO–O– linking the monomers. Polyurethanes are made by condensation of isocyanates (– NCO) with alcohols.

Polyvinyl Acetate A thermoplastic polymer created by polymerizing vinyl ethanoate, CH2:CHOOCH3. It is utilized as a paper and fabric coating as well as an adhesive.

Porphyrin It refers to any of a number of cyclic organic structures with the important property of forming complexes with metal ions. Iron porphyrins (e.g., heme in hemoglobin) and magnesium porphyrins, chlorophyll, the photosynthetic pigment in plants, are examples of such metalloporphyrins. The majority of metalloporphyrins found in nature are conjugated to proteins to create a variety of essential molecules such as hemoglobin, myoglobin, and the cytochromes.

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Potentiometric Titration It is a type of titration in which an electrode is used in the reaction mixture. Monitoring the electrode potential of this during the titration can help you find the end point.

Pressure The pressure on a surface caused by forces from another surface or a fluid      “/Z   '   J   The pascal (Pa) is the unit of measurement.

Primary Standard It refers to a substance that can be used directly to prepare standard solutions without the use of another concentration standard. Primary standards should be simple to purify, dry, capable of being preserved in a pure condition, unaffected by air or CO2, have a high molecular weight (to limit the impact of weighing errors), be stoichiometric, and easily soluble. Any potential contaminants should be easily discernible.

Producer Gas ?     ?5$Y"/”=% 5$/Y$$”=%    5#/Y#$”=    ’ '      steam over a thick layer of white-hot coke. The hot air gas is utilized to prevent heat loss and is employed in industrial heating, such as the firing of retorts and glass furnaces.

Promoter (Activator) It is a chemical that boosts a catalyst’s efficiency and does not catalyze the process but rather aids the catalytic activity.

Proof It is a measure of the ethanol concentration of alcoholic beverages. Proof     · Q    ‰/”     >  `    ‰“ž    5$!#”>  #ŽZ&= · Kingdom. The degree of proof indicates how many parts proofs there are #//  > #//Z 

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Propane (C3H8) A gaseous alkane derived from either the gaseous portion of crude oil or the cracking of heavier fractions. As propane can be liquefied under pressure, stored in cylinders, and transported readily, it is mostly used as a fuel for heating and cooking. Propane is the third alkane in the homologous series.

Propane-1,2,3-trio A colorless viscous liquid produced as a byproduct of soap production through the interaction of animal fats with sodium hydroxide. It’s a solvent and a plasticizer.

Propanone (Acetone; CH3COCH3) It is a colorless liquid ketone that is employed as a solvent and in the production of methyl 2-methyl-propanoate (from which polymethylmethacrylate is produced). Propanone is derived from propene via air-oxidation of propan-2-ol or as a byproduct of the cumene process. Propenal (acrolein; CH2:CHCHO) is a colorless, unsaturated aldehyde with a pungent smell. Acrylic resins can be made by polymerizing it.

Propene (Propylene; C3H6) An alkene that is gaseous. Propene is not generally present in the gaseous crude-oil fraction, but it can be extracted from heavier fractions using catalytic cracking. This is the most important industrial supply. Propene is the organic starting material for the manufacturing of propan-2-ol, which is needed for the production of propanone (acetone), as well as the starting material for the production of polypropene (polypropylene).

Propenoic Acid It refers to unsaturated liquid carboxylic acid with a pungent smell. The acid and its esters are used.

Prosthetic Group It is a conjugated protein’s nonprotein component. The heme group in hemoglobin, for example, is an example of a prosthetic group, as are the coenzyme components of many enzymes.

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Protamine One of a class of polypeptides made consisting of a few amino acids. They are soluble in water, dilute acids, and bases. They do not coagulate when heated. When protamines are hydrolyzed, they produce a high proportion of basic amino acids, particularly arginine, alanine, and serine. They are found in vertebrate sperm, where they compress the DNA into a condensed form.

Protein It refers to one of a wide range of chemicals essential to the construction and operation of all living creatures. Proteins are polypeptides which mean that they are built up of amino acid molecules connected together by peptide links. Their molecular weight can range between a few thousand and several million. Proteins contain approximately 20 amino acids. Simple proteins are made up of only amino acids. The amino acids in conjugated proteins are linked to other groups. Proteins can be made up of one or more polypeptide chains.

Proteoglycan (Mucoprotein) A form of glycoprotein composed of long branching heterogeneous chains of glycosaminoglycan molecules connected to an amino acid core. They differ from more usual glycoproteins in that they contain higher carbohydrate content, a serine-rich protein core, and a higher molecular weight.

Proton Number It refers to the number of protons in an atom’s nucleus. Because the electron structure, which governs chemical bonding, is dependent on electrostatic attraction to the positively charged nucleus, the proton number controls the element’s chemical properties.

Pseudo-First Order Defining a reaction that appears to have first-order kinetics under certain conditions, despite the fact that the ‘true’ order is greater than one. For example, when an ester is hydrolyzed in the presence of a significant volume of water, the concentration of water remains relatively constant. Thus, the rate of reaction is experimentally observed to be proportional to the ester concentration (even though it also depends on the amount of water present). A reaction of this type is referred to as ‘bimolecular of the first order.’

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Purine It is a simple nitrogenous organic molecule with a double ring structure. Purine group members include adenine and guanine, which are nucleic acid components, as well as various plant alkaloids such as caffeine and theobromine.

Pyridine (C5H5N) It is an organic liquid with the formula C$H$N. The molecules are isoelectronic with benzene and have a hexagonal planar ring. Pyridine is an aromatic heterocyclic compound in which the electrons in the carbon– carbon pi bonds and the nitrogen lone pair are delocalized over the ring of atoms. The substance is derived from coal tar and is utilized as a solvent and raw material in organic synthesis.

Pyridoxine (Vitamin B6) It is one of the vitamins of the water-soluble B group. Yeast and some seeds (such as wheat and corn), liver, and, to a lesser extent, milk, eggs, and leafy green vegetables are also good sources. The vitamin is also synthesized by bacteria in the intestine. Pyridoxine produces a coenzyme that is involved in numerous stages of amino acid metabolism.

Pyrimidine A simple nitrogenous organic molecule with a ring structure that is found in the pyrimidine bases cytosine, thymine, and uracil, which are components of nucleic acids, as well as in thiamine (vitamin B1).

Pyrometer A device used in the chemical industry to detect high temperatures, such as those found in reactor vessels.

Pyrone (C5H4O2) A compound with a six-membered ring comprising five carbon atoms and one oxygen, one of which is connected to another oxygen in a carbonyl group. Depending on the position of the carbonyl relative to the oxygen hetero element, the pyrone ring structure can take one of two forms. It can be found in a variety of natural goods.

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Pyrrole ((CH)4NH) A five-membered heterocyclic liquid aromatic compound comprising four carbon atoms and one nitrogen atom and contains significant biochemical derivatives such as chlorophyll and heme pyruvate. The formula CH3COCOO– is an intermediary in various metabolic processes, including glycolysis and gluconeogenesis. Pyruvate is also a precursor for the amino acids alanine, valine, and leucine.

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Q Qualitative Analysis Analyzes performed with the goal of determining the constituents of a sample. Classical approaches entailed simple preliminary tests followed by a meticulously planned programme of systematic testing and processes. A variety of spectroscopic techniques are used in modern procedures. In contrast, consider quantitative analysis.

Quantitative Analysis Analyzes performed to determine the concentration of one or more components in a sample. Volumetric and gravimetric analyzes are two classic wet methods. A variety of instrumental techniques are also utilized, such as polarography and other types of chromatography and spectroscopy. Contrast qualitative analysis.

Quantized It refers to defining a physical quantity that can only accept discrete values rather than a continuous range of values. Thus, in an atom or molecule, the electrons surrounding the nucleus can only have certain energies, E1, E2, and so on, and cannot have intermediate values. Similarly, electrons in atoms and molecules have quantized spin angular momentum and orbital angular momentum.

Quantum (Plural Quanta) It is a specific amount of energy that is released or absorbed throughout a process. Energy frequently behaves as though it has been ‘quantized’ in this way. The photon is the quantum of electromagnetic radiation. The study of quantum mechanics

Quantum Number It is an integer or half integer indicating the value of a quantized physical quantity (energy, angular momentum, etc.).

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Quantum States It is a state of an atom, electron, particle, or other entity defined by a unique set of quantum numbers. For example, in its ground state, the hydrogen atom has an electron in the K shell, which is described by the four quantum numbers: n = 1, l = 0, m = 0, ms = ½. There are two electrons in the helium atom: n = 1, l = 0, m = 0, ms = ½ n = 1, l = 0, m = 0, ms = –½

Quantum Theory A mathematical theory developed by German physicist Max Planck (1848– 1947) to explain the radiation emitted by hot bodies. Quantum theory is founded on the assumption that for a given system, energy (or other physical quantities) can only be changed in discrete amounts.

Quantum Yield It is the number of reactive events in a photochemical reaction of a proton to generate a positive ion per absorbed photon. Ammonium compounds generated from ammonia and an acid are examples of quaternary compounds for example, NH3}&~Œ}4 +Cl–. Other amines can also add protons to form similar molecules. For example, methylamine (CH3NH2) produces the molecule [CH3NH3] + X, where X is an acid radical.

Quinoline (C9H7N) A colorless two-ring heterocyclic compound with an unpleasant odor that functions as a base and forms salts with acids. It was first synthesized from the alkaloid quinine and is found in bone oil and coal tar, where it is utilized to make drugs and dyestuffs.

Quinone It is a yellow crystalline organic compound with a pungent smell. It has a nonaromatic six carbon ring in its molecules and behaves as an unsaturated diketone with conjugated double bonds. It is employed in the production of dyestuffs. The scientific name is cyclohexadiene-1,4-dione. In electrochemistry, a platinum electrode in an equimolar solution of quinone and hydroquinone (benzene-1,4-diol; C6H4(OH)2) is employed as a reference electrode. C6H4(OH)2~&6H4O2 + 2H+ + 2e is the reaction. This is referred to as a quinhydrone electrode.

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R Racemization It is the transformation of an optical isomer into an equal mixture of optically inactive enantiomers.

Rad A unit of absorbed dose of ionizing radiation defined as 10–2 joule of energy absorbed in one kilogram of material.

Radiation In general, energy is emitted from a source as waves (light, sound, etc.) or as moving particles (beta rays or alpha rays).

Radioactive Dating (Radiometric Dating) It is a method of dating archaeological specimens, rocks, and other materials by measuring the extent to which a radionuclide has decayed to produce a product.

Radioactivity It is the release of radiation as a result of the breakup of certain unstable nuclides. The three most important types of radiation that occur are the emission of alpha particles, beta particles, and gamma rays. Radioactive decay is the process through which one nuclide transforms into another.

Radiochemistry It refers to the study of the chemistry of radioactive isotopes of elements. Preparation of radioactive compounds, separation of isotopes by chemical reactions, use of radioactive labels in mechanism studies, and investigations on the chemical reactions and compounds of transuranic elements are all topics covered in radiochemistry.

Radioisotope It is an element’s radioactive isotope. Tritium, for example, is a hydrogen radioisotope. Radioisotopes are widely employed in research as radiation

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sources and as tracers in chemical reaction studies. Thus, if one atom in a compound is replaced by a radioactive nuclide of the element (a label) the chemical reaction can be tracked. In medicine, radioisotopes are employed for diagnosis and treatment.

Radiolysis High-energy radiation causes a chemical reaction (x-rays, gamma rays, or particles).

Radio Waves It is a type of electromagnetic radiation that has wavelengths longer than a few millimeters.

/  The liquid that remains after a dissolved substance has been extracted with a solvent. Look up solvent extraction.

/  A sugar found in sugar beets. It is a trisaccharide composed of units of fructose, galactose, and glucose.

Raschig Process It is a method for producing chlorobenzene, and thus phenol, from benzene. Benzene vapor, hydrogen chloride, and air are passed over a copper(II)       5"/Z&= &6H6 + 2HCl + O2 ~ &6H$Cl + 2H2O. The chlorobenzene is converted to phenol by reaction with water over a silicon    5‰$Z&= &6H$Cl + H2| ~ }&  &6H$OH It is named for the German chemist Fritz Raschig (1863–1928).

Rate Constant It is the proportionality constant in a rate expression for a chemical process. `   ‚~&% ? %          concentration of A multiplied by the concentration of B; i.e., rate = k[A] [B], where k is the rate constant for this particular reaction. The constant is independent of the reactant concentrations but relies on temperature; thus, the temperature at which k is measured must be specified. The units of k

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change according to the number of terms in the rate expression, but they are easily found by recalling that rate has units of s–1.

Rate-Determining Step In a multistep reaction, the slowest step. Many chemical reactions are composed of a number of steps, the one with the lowest rate determining the overall process rate. The total pace of a reaction cannot be greater than the rate of the slowest step. For example, the first step in the reaction between acidified potassium iodide solution and hydrogen peroxide is the ratedetermining step: H2O2 + I–~}2O + OI– (slow) H+ + OI–~}|`5 =}|` + H+ + I–~`2 + H2O (fast).

Rate of Reaction The amount of reactant consumed in a chemical reaction in one unit of time. It thus represents a count of the number of effective collisions between reactant molecules. The rate of a reaction can be assessed by the rate at which the reactants disappear or the rate at which the products are generated. Temperature, pressure, reactant concentration, light, and the activity of a catalyst are the primary elements influencing reaction rate. The units for measuring the rate of a reaction are typically mol dm–3 s–1.

Rationalized Units A unit system in which the equations have a logical structure tied to the system’s shape. SI units comprise a rationalized unit system. It contains a    ¨           ‰¨ formulas dealing with radial symmetry.

Raw Material A material used to make other substances. In the chemical process of producing ammonia from air or complex such as coal and petroleum used to make a wide range of products.

Rayon A synthetic fiber made from wood pulp (cellulose). There are two kinds. The cellulose is dissolved in carbon disulfide and sodium hydroxide to produce viscose rayon. The solution is forced through a fine nozzle into an acid bath, where the fibers are regenerated. By dissolving cellulose acetate in

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an organic solvent and forcing the solution through a nozzle, acetate rayon is formed. The solvent is evaporated, and the cellulose acetate fibers are formed.

Reactive Dye It is a dye that adheres to the fibers of a cloth by creating covalent chemical bonds with the fabric’s composition. Reactive dyes include those used to color the cellulose fibers in rayon.

Reagent It refers to a substance that reacts with another (the substrate). The word is also applied to typical laboratory chemicals used for experimentation and analysis, such as sodium hydroxide and hydrochloric acid.

Rearrangement It is a reaction in which the groups of a compound reorganize to generate a new compound. The Beckmann rearrangement is one example.

/       \  ?            Ž” water; subsequent distillation cannot remove any more water. It is used as an industrial solvent.

Redox Concerning the processes of oxidation and reduction, which are inextricably linked in the sense that during oxidation by chemical agents, the oxidizing agent itself becomes reduced, and vice versa. As a result, an oxidation process is always followed by a reduction phase. This is also true in electrochemical processes, with oxidation occurring at the anode and reduction occurring at the cathode. These systems are frequently referred to as redox systems, especially when both compounds are of interest. The redox potential, or      %˜­%_  ?[   Normally, redox potentials are expressed as reduction potentials. Electrochemical measurements are used to derive the values, which are referred to the H+/H2    ˜­ [  %    >    ?      Thus, in a redox reaction, the half reaction with the highest positive value of

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Reduction It is the gain of electrons by atoms, molecules, ions, and so on. It frequently involves the removal of oxygen from a compound or the addition of hydrogen. Reduction can be accomplished chemically, i.e., with the application of reducing agents (electron donors), or electrically, with the reduction process taking place at the cathode.

/   It is the removal of contaminants from a substance or the extraction of a substance from a mixture. Petroleum refining is an extremely significant industrial process.

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245

Terpene Any of a class of natural unsaturated hydrocarbons with formulae (C$H8)n, found in plants. Terpenes consist of isoprene units, CH2=C(CH3)CH=CH2. Monoterpenes have two units (C10H16), diterpenes four units (C20H32), triterpenes six units (C30H48), etc. Sesquiterpenes have three isoprene units (C#$H24).

Terylene (Trademark) A polymer made by condensing benzene-1,4-dicarboxylic acid (terephthalic acid) and ethane-1,2-diol (ethylene glycol), used for making fibers for textiles.

Tesla It refers to the SI unit of magnetic flux density, equal to a flux density of one weber of magnetic flux per square meter. 1 T = 1 Wb m–2. The unit is named for the Croatian–US electrical engineer Nikola Tesla (1870–1943). Symbol: T.

Tetrachloroethene A colorless poisonous liquid organic compound (a haloalkene) used as a solvent in dry cleaning and as a de-greasing agent.

Tetrachloromethane (Carbon Tetrachloride; CCl4) A colorless nonflammable liquid made by the chlorination of methane. Its main use is as a solvent although it is being replaced by other compounds for safety reasons.

+  * "2:CF2) A gaseous organic compound (a fluorocarbon and a haloalkene) used to make the plastic polytetrafluoroethene (PTFE).

Tetrahydrofuran (THF; C4H8O) A colorless liquid widely used as a solvent and for making polymers.

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Tetrapyrrole A structure of four pyrrole molecules linked together, found in heme, chlorophyll, and other compounds. Usually, a metal ion is coordinated to the four nitrogen atoms on the pyrrole rings.

Theobromine An alkaloid found in the cacao bean. Its action is similar to caffeine. The systematic name is 3,7-dimethylxanthine.

Theophylline An alkaloid similar in action to caffeine and its systematic name is 1,3dimethylxanthine.

Thermal Dissociation It is the decomposition of a chemical compound into component atoms or molecules by the action of heat. Often it is temporary and reversible.

Thermochemistry The branch of chemistry concerned with heats of reaction, solvation, etc.

Thermodynamics The study of heat and other forms of energy and the various related changes in physical quantities such as temperature, pressure, density, etc. The first law of thermodynamics states that the total energy in a closed system is conserved (constant). In all processes energy is simply converted from one form to another, or transferred from one system to another.

Thiamine (Vitamin B1) It is one of the water-soluble B-groups of vitamins. Good sources of thiamine are unrefined cereal grains, liver, heart, and kidney. Thiamine deficiency predominantly affects the peripheral nervous system, the gastrointestinal tract, and the cardiovascular system. Thiamine has been shown to be of value in the treatment of beriberi. Thiamine, in the form of thiamine diphosphate, is the coenzyme for the decarboxylation of acids such as pyruvic acid.

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Thiazine (C4H4NS) Any of a group of heterocyclic organic compounds that have a six-membered ring containing four carbon atoms, one nitrogen atom, and one sulfur atom.

Thiazole (C3H3NS) A colorless volatile liquid, a beterocyclic compound with a five-membered ring containing three carbon atoms, one nitrogen atom, and one sulfur atom. It resembles PYRIDINE in its reactions and is used in making dyes.

Thin-Layer Chromatography A type of chromatography widely used for the analysis of mixtures. Thinlayer chromatography employs a solid stationary phase, such as alumina or silica gel, spread evenly as a thin layer on a glass plate. A base line is carefully scratched near the bottom of the plate, and a small sample of the mixture is spotted onto the base line. The plate is then stood upright in solvent, which rises up to the baseline and beyond by capillary action. The components of the spot of the sample will dissolve in the solvent and tend to be carried up the plate. However, some of the components will cling more readily to the solid phase than others and will not move up the plate so rapidly. In this way, different fractions of the mixture eventually become separated.

Thiocarbamide (Thiourea; NH2CSNH2) It is a colorless crystalline organic compound (the sulfur analog of urea). It is converted to the inorganic compound ammonium thiocyanate on heating. It is used as a sensitizer in photography and in medicine.

+* *    # `     €Q€™           generally more reactive than the corresponding oxygen compound. With halogen compounds they form sulfonium compounds: CH3SCH3 + CH3& ~ 5&}3)3 S+Cl– They can also be oxidized to sulfoxides: (CH3)2S|~5&}3)2S=O

Thiophene (C4H4S) A colorless liquid that smells like benzene, a heterocyclic compound with a five-membered ring containing four carbon atoms and one sulfur atom. It

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occurs as an impurity in commercial benzene and is used as a solvent and in organic syntheses.

Titration A procedure in volumetric analysis in which a solution of known concentration (called the titrant) is added to a solution of unknown concentration from a burette until the equivalence point or end point of the titration is reached.

Toluidine An aromatic amine used in making dyestuffs and drugs. There are three isomers; the 1,2-(ortho-aminotoluene) and 1,3- (meta-) forms are liquids, the 1,4- (para-) isomer is a solid.

Torr  _    #/#"$J!Ž/  5#""" = One torr is equal to one mmHg. The unit is named for the Italian physicist Evangelista Torricelli (1609–47).

Tracer An isotope of an element used to investigate chemical reactions or physical processes (e.g., diffusion).

Transition State A short-lived high-energy molecule, radical, or ion formed during a reaction between molecules possessing the necessary activation energy. The transition state decomposes at a definite rate to yield either the reactants again or the final products. The transition state can be considered to be at the top of the energy profile.      %®¹º®°¹°º»~®¹º _ > is as follows. X approaches YZ and when it is close enough the electrons are rearranged producing a weakening of the bond between Y and Z. A partial bond is now formed between X and Y producing the transition state. Depending on the experimental conditions, the transition state either breaks down to form the products or reverts back to the reactants.

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Transition Temperature It is a temperature at which some definite physical change occurs in a substance. Examples of such transitions are change of state, change of crystal structure, and change of magnetic behavior.

Triazine (C3H3N3) It is a heterocyclic organic compound with a six-membered ring containing three carbon atoms and three nitrogen atoms. There are three isomers used as dyestuffs and herbicides.

Triazole (C2H3N3) Triazole is a heterocyclic organic compound with a five-membered ring containing two carbon atoms and three nitrogen atoms. There are two isomers.

Trichloroethanal A colorless liquid aldehyde made by chlorinating ethanal. It was used to make the insecticide DDT. It can be hydrolyzed to give 2,2,2-trichloroethanediol (chloral hydrate, CCl3CH(OH)2). Most compounds with two –OH groups on the same carbon atom are unstable. However, in this case the effect of the three chlorine atoms stabilizes the compound. It is used as a sedative.

Trichloromethane (Chloroform; CHCl3) A colorless volatile liquid formerly used as an anesthetic. Now its main use is as a solvent and raw material for making other chlorinated compounds. Trichloromethane is made by reacting ethanal, ethanol, or propanone with chlorinated lime.

Triiodomethane A yellow crystalline compound made by warming ethanal with an alkaline solution of an iodide: CH3&}|"`Y‰|}Y~&}`3 + HCOO– + 3H2. The reaction also occurs with all ketones of general formula CH3COR (R is an alkyl group) and with secondary alcohols CH3CH(OH)R. Iodoform is used as a test for such reactions (the iodoform reaction).

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Trimethylaluminum A colorless liquid produced by the reduction of dimethyl aluminum chloride using sodium. It ignites spontaneously on contact with air and reacts violently with water, acids, halogens, alcohols, and amines. Aluminum alkyls are used in the Ziegler process for the manufacture of high-density polyethene. Trimolecular. Describing a reaction or step that involves three molecules interacting simultaneously with the formation of a product. For example, the final step in reaction between hydrogen peroxide and acidified potassium iodide is trimolecular: HOI + H+ + I–~`2 + H2O. It is uncommon for reactions to take place involving trimolecular steps.

Trinitrotoluene A yellow crystalline solid highly unstable substance used as an explosive. The compound is made by nitrating methylbenzene and the nitro groups are in the 2, 4, and 6 positions.

Triple bond A covalent bond formed between two atoms in which three pairs of electrons contribute to the bond. One pair forms a sigma bond (equivalent to a single bond) and two pairs give rise to two pi bonds. It is conventionally represented  % }Y&Ÿ&Y}   ¬^¹Œ˜Q

Triple Point The only point at which the gas, solid, and liquid phases of a substance can  ?_    5!"#Ž^ #/#"$ = used to define the kelvin.

Tritium It is a radioactive isotope of hydrogen of mass number 3. The nucleus contains 1 proton and 2 neutrons. Tritium decays with emission of low energy beta radiation to give 3He. The half-life is 12.3 years. It is useful as a tracer in studies of chemical reactions. Compounds in which 3H atoms replace the usual 1H atoms are said to be tritiated. A positive tritium ion, T+, is a triton.

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Tropylium Ion It is the positive ion C7H7+ having a symmetrical seven-membered ring of carbon atoms. The tropylium ion ring shows non-benzenoid aromatic properties.

Turpentine (Pine-Cone Oil) A yellow viscous RESIN obtained from coniferous trees. It can be distilled to produce turpentine oil (also known simply as turpentine), used in medicine and as a solvent in paints, polishes, and varnishes.

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U Ubiquinone An electron-transporting coenzyme that is a component in the electrontransport chain and was formerly called coenzyme Q.

Ultracentrifuge A high-speed centrifuge used for separating out very small particles. The sedimentation rate depends on the particle size, and the ultracentrifuge can be used to measure the mass of colloidal particles and large molecules (e.g., proteins).

Ultraviolet (UV) It is a form of electromagnetic radiation, shorter in wavelength than visible light. Ultraviolet wavelengths range between about 1 nm and 400 nm. Ordinary glass is not transparent to these waves; quartz is a much more effective material for making lenses and prisms for use with ultraviolet. Like light, ultraviolet radiation is produced by electronic transitions between the outer energy levels of atoms. However, having a higher frequency, ultraviolet photons carry more energy than those of light and can induce photolysis of compounds and photoionization.

Unimolecular Describing a reaction (or step) in which only one molecule is involved. For ? %  >      € ~€<  one atom is involved in each disintegration. In a unimolecular chemical reaction, the molecule acquires the necessary energy to become activated and then decomposes. The majority of reactions involve only bimolecular steps. The following reactions are all unimolecular: N2O4~Œ|2 PCl$~ PCl3 + Cl2 CH3CH2&~&2H4 + HCl

Unit A reference value of a quantity used to express other values of the same quantity.

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Unit Cell The smallest group of atoms, ions, or molecules that, when repeated at regular intervals in three dimensions, will produce the lattice of a crystal system. There are seven basic types of unit cells, which result in seven crystal systems.

Unit Processes (Chemical Conversions) The recognized steps used in chemical processes, e.g., alkylation, distillation, hydrogenation, pyrolysis, nitration, etc. Industrial processing and the economics, design, and use of the equipment are based on these unit processes rather than consideration of each reaction separately.

Universal Indicator (Multiple-Range Indicator) It is a mixture of indicator dyestuffs that shows a gradual change in color over a wide pH range. A typical formulation contains methyl orange, methyl red, bromothymol blue, and phenolphthalein and changes through a red, orange, yellow, green, blue, and violet sequence between pH 3 and pH 10. Several commercial preparations are available as both solutions and test papers.

Unsaturated Compound It is an organic compound that contains at least one double or triple bond between two of its carbon atoms. The alkenes and alkynes are examples of unsaturated compounds. Unsaturated compounds typically undergo additional reactions to form single bonds.

UPVC Unplasticized PVC; a hardwearing form of PVC used in building work (e.g., for window frames).

Urea A white crystalline compound made from ammonia and carbon dioxide. It is used in the manufacture of urea–formaldehyde (methanal) resins. Urea is the end product of metabolism in many animals and is present in urine.

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Urea–Formaldehyde Resin A synthetic polymer made by copolymerization urea with formaldehyde (methanal, HCHO).

Urethane It refers to poisonous flammable organic compound, used in medicine, as a solvent, and as an intermediate in the manufacture of polyurethane resins.

Uric Acid A nitrogen compound produced from purines. In certain animals (uricotetic animals), it is the main excretory product resulting from breakdown of amino acids. In humans, uric acid crystals in the joints are the cause of gout.

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V Vacuum Distillation It refers to the distillation of liquids under a reduced pressure, so that the boiling point is lowered. Vacuum distillation is a common laboratory technique for purifying or separating compounds that would decompose at their ‘normal’ boiling point.

Figure 74. Vacuum distillation. Source: Image by Wikimedia.

Valence (Valency) It is the combining power of an element or radical, equal to the number of hydrogen atoms that will combine with or displace one atom of the element. For simple covalent molecules the valence is obtained directly, for example C in CH4 is tetravalent; N in NH3 is trivalent. For ions the valence is regarded as equivalent to the magnitude of the charge; for example, Ca2+ is divalent, CO32– is a divalent radical. The rare gases are zero-valent because they do not form compounds under normal conditions. As the valence for many elements is constant, the valence of some elements can be deduced without reference to compounds formed with hydrogen. Thus, as the valence of chlorine in HCl is 1, the valence of

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aluminum in AlCl3 is 3; as oxygen is divalent (H2O) silicon in SiO2 is tetravalent. The product of the valence and the number of atoms of each element in a neutral compound must be equal. For example, in Al2O3 for the two aluminum atoms (valence 3) the product is 6 and for the three oxygen atoms (valence 2) the product is also 6.

Vapor A gas formed by the vaporization of a solid or liquid. Some particles near the surface of a liquid acquire sufficient energy in collisions with other particles to escape from the liquid and enter the vapor; some particles in the vapor lose energy in collisions and re-enter the liquid. At a given temperature equilibrium is established, which determines the vapor pressure of the liquid at that temperature.

Vapor Density The ratio of the mass of a certain volume of a vapor to the mass of an equal volume of hydrogen (measured at the same temperature and pressure). Determination of vapor densities is one method of finding the relative molecular mass of a compound (equal to twice the vapor density). Victor Meyer’s method, Dumas’ method, or Hofmann’s method can be used.

Vaporization The process by which a liquid or solid is converted into a gas or vapor by heat. Unlike boiling, which occurs at a fixed temperature, vaporization can occur at any temperature. Its rate increases as the temperature rises.

Vapor Pressure The pressure exerted by a vapor. The saturated vapor pressure is the pressure of a vapor in equilibrium with its liquid or solid. It depends on the nature of the liquid or solid and the temperature.

Vat Dyes It is a class of insoluble dyes applied by first reducing them to derivatives that are soluble in dilute alkali. In this condition they have a great attraction for certain fibers, such as cotton. The solution is applied to the material and the insoluble dye is regenerated in the fibers by atmospheric oxidation. Indigo and indanthrene are examples of vat dyes.

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Vicinal Positions It is the positions in a molecule at adjacent atoms. For example, in 1,2-dichloroethane the chlorine atoms are in vicinal positions, and this compound can thus be named vic-dichloroethane.

Vinegar It is a dilute solution5  ‰”> =    5  =% often with added coloring and flavoring such as caramel. Natural vinegar is produced by the bacterial fermentation of cider or wine; it can also be made synthetically.

Vinylation It is a catalytic reaction in which a compound adds across the triple bond of ethyne (acetylene) to form an ethenyl (vinyl) compound. For example, an 

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Vitamin One of a number of organic compounds that is essential in small quantities for metabolism. The vitamins have no energy value; most of them seem to act as catalysts for essential chemical changes in the body, each one influencing a number of vital processes. Vitamins A, D, E, and K are the fat-soluble vitamins, occurring mainly in animal fats and oils. Vitamins B and C are the water-soluble vitamins. If a diet lacks vitamins, this results in the breakdown of normal bodily activities and produces disease symptoms. Q               necessary vitamins in the diet. Plants can synthesize vitamins from simple substances, but animals generally require them in their diet, though there are exceptions to this. These include vitamins synthesized by bacteria in the gut, and some that can be manufactured by the animal itself. A precursor of vitamin D2 (ergosterol), for example, can be converted in the skin by ultraviolet radiation.

Vitamin A A fat-soluble vitamin (a derivative of the yellow pigment, carotene) occurring in milk, butter, cheese, liver, and cod-liver oil. It can also be formed in the body by oxidation of carotene, which is present in fresh green vegetables

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Key Concepts in Chemistry

and carrots. Deficiency in vitamin A can result in a reduced resistance to disease and in night blindness.

Vitamin B complex It is a group of ten or more water-soluble vitamins, which tend to occur together. They can be obtained from whole grains of cereals and from meat and liver. Since the B vitamins are present in most unprocessed food, deficiency diseases only occur in populations living on restricted diets. Many of the B vitamins act as coenzymes involved in the normal oxidation of carbohydrates during respiration. The vitamins of the B complex include thiamine (vitamin B1), riboflavin (vitamin B2), nicotinic acid (niacin),      5>  ‚$=%  ? 5>  ‚Ž=%       (vitamin B12), biotin, lipoic acid, and folic acid.

Vitamin C (Ascorbic Acid) It is a water-soluble vitamin, which is widely required in metabolism. The major sources of vitamin C are fresh fruit and vegetables and severe deficiency results in scurvy.

Vitamin D A fat-soluble vitamin found in fish-liver oil, butter, milk, cheese, egg yolk, and liver. Its principal action is to increase the absorption of calcium and phosphorus from the intestine. The vitamin also has a direct effect on the calcification process in bone. Deficiency results in inadequate deposition of calcium in the bones, causing rickets in young children and osteomalacia in adults. The term vitamin D refers, in fact, to a group of compounds, all sterols, of very similar properties. The most important are vitamin D2 (calciferol) and vitamin D3 (cholecalciferol). Precursors of these are converted to the vitamins in the body by the action of ultraviolet radiation.

Vitamin E (Tocopherol) A fat-soluble vitamin found in wheat germ, dairy products, and in meat. Severe deficiency in infants may lead to high rates of red-blood cell destruction and hence to anemia. However, there are very few deficiency effects apparent in adults.

Key Concepts in Chemistry

259

Vitamin K (Phylloquinone; Menaquinone) It is a fat-soluble vitamin that is required to catalyze the synthesis of prothrombin, a blood-clotting factor, in the liver. Intestinal microorganisms are capable of synthesizing considerable amounts of vitamin K in the intestine and this, together with dietary supply, ensures that deficiency is unlikely to occur in any but the newborn. A newborn child may be deficient because the intestine is sterile at birth and the level supplied by the mother during gestation is limited. Thus, during the first few days of life bloodclotting deficiency may be observed, but this is readily rectified by a small injection of the vitamin.

Volt The SI unit of electrical potential, potential difference, and E.M.F., defined as the potential difference between two points in a circuit between which a constant current of one ampere flows when the power dissipated is one watt. 1 V = 1 J C–1. The unit is named for the Italian physicist Alessandro Volta 5#!‰$Y#ž!=

Volumetric Analysis It is one of the classical wet methods of quantitative analysis. It involves measuring the volume of a solution of accurately known concentration that is required to react with a solution of the substance being determined. The solution of known concentration (the standard solution) is added in small portions from a burette. The process is called a titration and the equivalence point is called the end point. End points are observed with the aid of indicators or by instrumental methods, such as conduction or light absorption. Volumetric analysis can also be applied to gases. The gas is typically held over mercury in a graduated tube, and volume changes are measured on reaction or after absorption of components of a mixture.

Vulcanite (Ebonite) A hard black insulator made by vulcanizing rubber with a large amount of sulfur.

260

Key Concepts in Chemistry

Vulcanization It refers to a process of improving the quality of rubber (hardness and     =    5  #$/Z&= Accelerators are used to speed up the reaction. Certain sulfur compounds can also be used for vulcanization.

Key Concepts in Chemistry

261

W Water (H2O)   _ [ /Z& %    %   #//Z&`       }2O molecules. Due to the presence of two lone pairs the atoms do not lie in a straight line, the angle     ?         #/$Z] the distance between each hydrogen atom and the oxygen atom is 0.099 nm. When ice forms, hydrogen bonds some 0.177 nm long develop between the hydrogen atom and oxygen atoms in adjacent molecules, giving ice its tetrahedral crystalline structure with a density of 916.8 kg m–3 at STP. Different ice structures develop under higher pressures. When ice melts to form liquid water, the tetrahedral structure breaks down, but some hydrogen bonds continue to exist; liquid water consists of groups of associated water molecules, (H2O)n, mixed with some monomers and some dimers.

Figure 75. Water molecules. Source: Image by Wikimedia.

Water Gas A mixture of carbon monoxide and hydrogen produced when steam is passed over red-hot coke or made to combine with hydrocarbons, e.g., C(s) + H2O(g) ~&|5=}2(g) The amount of hydrogen can be increased by combining it with the water gas shift reaction: CO + H2|~&|2 + H2 Water gas was once an important source of hydrogen for the production of ammonia. Most hydrogen is now obtained from methane by steam reforming. CH4(g) + H2|5=~&|5="}2(g) The production of water gas using methane is an important step in the preparation of hydrogen for ammonia synthesis.

262

Key Concepts in Chemistry

Watt Symbol: W The SI unit of power, defined as a power of one joule per second. 1 W = 1 J s–1. The unit is named for the British inventor James Watt (1739–1819).

Wave Function It is a function that describes the quantum state of a system in wave mechanics. The physical significance of the wave function for a particle is that the square of its absolute value at a point is proportional to the probability of finding the particle in a small element of volume, dxdydz, at   Q ¼

Wavelength It refers to the distance between the ends of one complete cycle of a wave. Wavelength         5=  _ 5>=     > Q 

Wave Mechanics A formulation of quantum mechanics put forward by the German physicist Erwin Schrödinger (1887–1961) in 1926, following the suggestion of the French physicist Louis de Broglie (1892–1987) that particles such as electrons might also have wavelike properties. The basic equation of wave mechanics is the Schrödinger equation, which is a wave equation describing the system. Solutions of the equation give rise to wave functions.

Wave Number This refers to the reciprocal of the wavelength of a wave. It is the number of wave cycles in unit distance, and is often used in spectroscopy. The unit is the meter–1 (m–1). The circular wave number (symbol: k) is given by: k = ¨¾Q ¾

Wax One of a group of water-insoluble substances with a very high molecular weight; they are esters of long-chain alcohols with fatty acids. Waxes form protective coverings to leaves, stems, fruits, seeds, animal fur, and the cuticles of insects, serving principally as waterproofing. For example, waxy deposits on some plant organs add to the efficiency of the cuticle in reducing transpiration, as well as cutting down airflow over the surface and forming

Key Concepts in Chemistry

263

a highly reflective surface, thus reducing energy available for evaporation. They may also occur in plant cell walls, e.g., leaf mesophyll. They are used in varnishes, polishes, and candles.

Weber The SI unit of magnetic flux, equal to the magnetic flux that, linking a circuit of one turn, produces an E.M.F. of one volt when reduced to zero at uniform rate in one second. 1 Wb = 1 V s. The unit is named for the German physicist Wilhelm Weber (1804–91). Symbol: Wb.

White Spirit A liquid hydrocarbon resembling kerosene obtained from petroleum, used as a solvent and in the manufacture of paints and varnishes.

Wurtz Reaction A reaction for preparing alkanes by refluxing a haloalkane (RX) with    €®Œ ~€€Œ ®   > > the coupling of two alkyl radicals. The Fittig reaction is a similar process for preparing alkyl-benzene hydrocarbons by using a mixture of halogen compounds. For example, to obtain methylbenzene: C6H$Cl + CH3Cl + 2Na ~&6H$CH3 + 2NaCl. In this mixed reaction phenylbenzene (C6H$C6H$) and ethane (CH3CH3) are also produced by side reactions. The Wurtz reaction is named for the French chemist Charles Adolphe Wurtz (1817–84), who developed the    #ž$$             €     5#ž"$Y 1910), a German chemist who worked with Wurtz. It is often called the Wurtz–Fittig reaction.

264

Key Concepts in Chemistry

X Xanthate A salt or ester of xanthic acid containing the ion –SCS(OR) or the group – SCS(OR) (where R is an organic group). Cellulose xanthate is used to make rayon.

Xanthene Chemical formula – (CH2(C6H4)2O). It is a yellow crystalline organic compound, used in making dyestuffs and fungicides.

Xanthic Acid (HSCS(OR)) It is any of several unstable organic acids (where R is an organic group). The esters and salts of xanthic acid have various industrial applications.

Xanthine It is a poisonous colorless crystalline organic compound that occurs in blood, coffee beans, potatoes, and urine. It is used as a chemical intermediate.

Xanthone A colorless crystalline organic compound found as a pigment in gentians and other flowers. It is used as an insecticide and in making dyestuffs.

Xanthophyll One of a class of yellow to orange pigments derived from carotene, the commonest being lutein.

Xanthoproteic Test It is a standard test for proteins. Concentrated nitric acid is added to the test solution. A yellow precipitate produced either immediately or on gentle heating indicates a positive result.

X-radiation An energetic form of electromagnetic radiation with the wavelength range 10–11 m to 10–8 m. X-rays are normally produced by absorbing high-energy

Key Concepts in Chemistry

265

electrons in matter. The radiation can pass through matter to some extent (hence its use in medicine and industry for investigating internal structures). It can be detected with photographic emulsions and devices like the GeigerMüller tube. X-ray photons result from electronic transitions between the inner energy levels of atoms. When high-energy electrons are absorbed by matter an x-ray line spectrum results. The structure depends on the substance and is thus used in x-ray spectroscopy. The line spectrum is always formed in conjunction with      {     5 = >  0 corresponds to the maximum x-ray energy, Wmax. This equals the maximum energy of electrons in the beam producing the x-rays. Wavelengths in the     >0 are caused by more gradual energy loss by the electrons, in the process called bremsstrahlung (braking radiation).

Figure 76. X-ray of palm. Source: Image by Pxfuel.

X-Ray Crystallography It refers to the study of the internal structure of crystals using the technique of x-ray diffraction.

X-Ray Diffraction A technique used to determine crystal structure by directing x-rays at the crystals and examining the diffraction patterns produced. At certain angles of incidence, a series of spots are produced on a photographic plate; these spots are caused by interaction between the x-rays and the planes of the atoms, ions, or molecules in the crystal lattice.

266

Key Concepts in Chemistry

Y Ylid (ylide) It is a type of zwitterion in which the two charges are on adjacent atoms.

Yocto Its symbol is: y a prefix denoting 10–24. For example, 1 yoctometer (ym) = 10–24 meter (m).

Yotta Its symbol is: Y a prefix denoting 1024. For example, 1 yottameter (Ym) = 1024 meter (m).

Key Concepts in Chemistry

267

Z Zeisel Reaction This refers to the reaction of ether with excess concentrated hydroiodic acid. On refluxing% ?   {  €|€™}`~}2O + €`€™`     { >       composition of the original ether. It was developed by S. Zeisel in 1886.

Zeolite It refers to a member of a group of hydrated aluminosilicate minerals, which occur in nature and are also manufactured for their ion-exchange and selective-absorption properties. They are used for water softening and for sugar refining. The zeolites have an open crystal structure and can be used as molecular sieves.

Zepto It is a prefix denoting 10–21. For example, 1 zeptometer (zm) = 10–21 meter (m).

Zero Order Describing a chemical reaction in which the rate of reaction is independent of the concentration of a reactant; i.e., rate = k[X]0. The concentration of the reactant remains constant for a period of time although other reactants are being consumed. The hydrolysis of 2-bromo-2- methylpropane using aqueous alkali has a rate expression, rate = k[2-bromo-2-methylpropane], i.e., the reaction is zero order with respect to the concentration of the alkali. The rate constant for a zero reaction has the units mol dm–3 s–1.

Zero-Point Energy The energy possessed by the atoms and molecules of a substance at absolute zero (0 K).

Zetta It is a prefix denoting 1021. For example, 1 zettameter (Zm) = 1021 meter (m).

268

Key Concepts in Chemistry

Zwitterion (Ampholyte Ion) It is an ion that has both a positive and negative charge on the same species. Zwitterions occur when a molecule contains both a basic group and an acidic group; formation of the ion can be regarded as an internal acid-base reaction. For example, amino-ethanoic acid (glycine) has the formula H2N.CH2. – COOH. Under neutral conditions it exists as the zwitterion H3N.CH2.COO–, which can be formed by transfer of a proton from the carboxyl group to the amine group. At low pH (acidic conditions) the ion +H3N.– CH2.COOH is formed; at high pH (basic conditions) H2N.CH2.COO– is formed.

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Index

A abbreviation 194 Abscisic Acid 1 Absolute Temperature 1 Absorption 2 absorption spectrum of chlorophyll. 7 Accelerator 2 Acetal 3 Acetyl CoA 3 Achiral 4 ‰%$%#%#Ž%# $ acidic group 269 $ acrylic polymer 6 activated charcoal 2 Active Site 7 Acyl halide 8 Adenine 9 Adenosine 9, 22  >##$%##! Adsorption 9

Aldehyde 11 Aldol Reaction 12 Aliphatic Compound 12 {  #$/%#$! Alkene 13 Alkoxide 14 allotrope 40 amine group 269 Amines 16   $$ Amino Sugar 17 Ammonia 17, 18 ammonium ions 182 amount of radioactive carbon lessens 41 An acyl halide 8 antiseptic 226 antitumor activity 6 Aromatic Compound 20 aromatic hydrocarbon 28, 29    ?  $! Atomicity 22 Azeotropic Distillation 23

276

Key Concepts in Chemistry

B Band Spectrum 26 beginning of dormancy in buds 1 benzene 137, 138 benzoic auxins 23 Bioassay 30   $Ž Boiling Point-Composition Diagram 31 Bomb calorimeter. 31 bone oil 214 buckminsterfullerene 40 Buffer 33 Bunsen Burner 33 Butane (C4H10) 34

C calcium oxide 36 Cannizzaro Reaction 37 Carbohydrate 39 Carbonation 40 Carbon Cycle 40 carbon dioxide 3, 10, 18 Carbonic Acid (H2CO3) 42 Carbonium ions 39 Carbon Monoxide (CO) 42 Carboxyhemoglobin 43 carboxylate ion 43 carboxylic acid 8, 11, 16, 19 Carcinogen 44 carcinogenic properties 29 &  & >‰$ Catalytic Cracking 46 Cationic Resin 46 Centrifugal Pump 47 CGS System 48 Chemical Bond 49 Chemical Combination Laws 49

&  ˜$/ &  ˜_  $/ &    Ž$   $    Ž$   #‰$        !$% !ž% ž‰% #‰ž% 268 Chemical structure of abscisic acid 1  %%‰%!%##%#‰%#$%#! &  ˜$# class of plant hormones 23 coenzymes 147 coloring material for fabric 87   ‰%$"%$‰%ŽŽ%!# colorless crystalline derivative of naphthalene 3 colorless crystalline organic compound 74   _‰Ž%‰ž%$/%$#        ##$     !‰% !$% !Ž% !ž% !“% ž/% ž%ž$ concentration 260 conducts electricity 90 connective tissue 228 consistency of the fruit 190     $    #\   $ copper-containing blood pigment 127 crystalline 126, 128, 131 crystalline carboxylic acid 29, 34 crystalline organic compound 214, Ž$ crystalline organic substance 226 crystalline solid produces 74

Index

crystallization of one constituent 109 cyclic sugar 19

D D-Block Elements 74       !$ defoliant chemical containing 10 Deionization 76 Delocalized Bond 77 Depression of Freezing Point 78 derivative of benzene (C6H6). 78 ƒ   $" Designating a benzene compound #ž$ >    ‰$ determine crystal structure 266 Deuterated Compound 79 Diagram of Bomb Calorimeter 37 Diazonium Compound 80 Diazotization mechanism. 81 Diffusion in a liquid. 81   $ž Dimethylbenzene 82 Dipole 83 direction of action 144 Disperse dyes. 84 Disproportionation 84    _$Ž ƒŒ5ƒ ? =ž$ Double Salt 86 Dryer deliquescent. 76

E ˜ˆ žž Elastin bovine 88 Electrochemical Equivalent 88 Electrochemistry. 89 electromagnetic radiation 2, 6

277

˜ \ƒ&  “/  \ “ Electron Diffraction 90 Electron Spin Resonance (ESR) 91 electron transport chain 147  \   [$" electrophilic substitution 173 Electrovalent Bond 93   %$Ž elimination of an adsorbed substance 94 Elimination Reaction 94 emission of electromagnetic radiation 197 energy 2, 7, 9, 10, 18, 21, 22 energy values 31 enzymes and proteins 91 equals the maximum energy 266 estimation of volume 27

F FAD (Flavin Adenine Dinucleotide) 102 Fehling’s Solution 102    #$ Filter Pump 103 Fine Structure 104 First-Order Reaction 104 Fischer–Tropsch Process 104      #/$   >  #/$ Flavoprotein 106 Fluorescein 106 Fluxional Molecule 108 Folic Acid 108 fossil fuels 40, 41, 42 fragments 114 Freezing Mixtures 110 Friedel–Crafts Reaction 111

278

Key Concepts in Chemistry

Fucoxanthin 112

G Gas Chromatography 113 General aldol reaction 12 ©##$ globulins 116 Glove Box 116 Glycan 117 Glycosaminoglycan (GAG) 119 Glyoxylate Cycle 119 gradual energy 266 group of proteins 116 GTP (Guanosine Triphosphate) 121 Guanosine (Guanine Nucleoside) 121

H Haloform 122 Halogenation 123 Hammer Mill 123 Heat of Crystallization 124 Heat of Dissociation 124 }  Œ [  #$ }  €  #$ }  Q  #$ Hemicellulose 126 Heptane (C7H16) 127 heterocyclic compound 214 heterocyclic liquid organic compounds 112 }    ‰$ Heterolytic Fission (Heterolysis) 128 Hexane (C6H14) 128 Hofmann Degradation 129 Homogeneous 129 Humectant 130

Hydrobromic Acid (HBr) 131 } ˆ 5} =#" Hydrogen 131, 132, 133, 134 hydrogen at extreme pressure 30 Hydrogenation 132 Hydrogen bonds 49 hydrogen for ammonia synthesis. 262 Hydrogensulfate 134 Hydrolysis 134

I ice temperature 102 Ignis Fatuus 136 Ignition temperature 136 Immiscible 137 Indicator 137 Indigo 137 Inductive Effect 137 Industry fossil fuel oil. 109 Infrared (IR) 138 Insertion Reaction 139 Inversion 139 Iodine 140 ion-exchange substance 19 Ionic Crystal 140 Isomerism 142

J Joule 144

K ^ #‰$ ^5{=#‰$ ^ Y˜   #‰$ Ketone Body 146 Kilogram 146 Kilowatt-Hour 147

Index

kinetic and potential energies of  “$ Kinetics 147

L Label 148       #/‰ Lactose 148 ¬  #‰“%#$/ ¬ #$/ ¬ } #$/ ¬ ?#$/ ¬  #$# ¬& #$# ¬#$ ¬ #$ ¬ #$" ¬_#$‰ Lithium Tetrahydridoaluminate(III) #$‰ ¬?>  #$$ logarithm to 194 Low-Density Lipoprotein (LDL) #$$ Low-density lipoproteins (LDLs) #$" ¬  *  #$$ ¬#$Ž lyophilic colloid 114 ¬  #$Ž

M Magnetic dipole moment. 83  #$ž   #$ž   #$“ marine organisms. 197  #$“

279

  #$“ mass spectrum of the material 160 mathematical theory 214 Matrix 160 measuring the energy 31 Mechanism 160 mechanism establishment 148 Melamine 160 Melting Point 161 Membrane 161 mercury thermometer 28 Metabolism 162 Metallocene 162 Metastable Species 162 Methanal 163 Methanoic Acid 163 method in quantitative analysis 44 method of dating 41 Methylbenzene 164 Methyl Methacrylate 164  €#Ž$ Q#Ž$ microorganisms 30 Mineral Acid 166 Mineral oils 182 mitochondria 91 mixture of carbon monoxide 237, 244, 262 ?  _      #$‰ Mole 167, 168 Molecular Crystal 167  #%"%‰%$%!%ž%#/%#%#"% #‰%#$%#!%#ž%/%%‰

N Naphtha 171 Natural Gas 172 neutral conditions 269

280

Key Concepts in Chemistry

Neutron Diffraction 172 Neutron Number 173 Nicotinamide adenine dinucleotide phosphate 171 nicotinic acid derivative 171 Nicotinic Acid (Niacin) 173 Ninhydrin 173 Nitric Acid 173 Œ [#!$ Œ  ‚ #!$ nonaromatic six carbon 214 Nonmetal 176 Normal Solution 176 Nucleic Acids 177 Nucleophilic Substitution 178

O Occlusion 181 Octadecanoic Acid 181 Octane 181 Octet 181 odorless, 42

  #“" One-pot synthesis 182 Optical Rotation 183 Orbital 183 Organic Acid 184 organic carboxylic acids 4 Organic Chemistry 184

   ‰$%‰ž organic matter 182 organic reaction 38 organic substance 78 Organometallic Compound 184 | #ž$%#žŽ Osmotic Pressure 186

     $“ Oxaloacetic Acid (OAA) 186 Oxidation 187

Oxyacid 187

?  $! Ozonolysis 188

P Pantothenic Acid 189 Paper chromatography 189 Partial Ionic Character 189 particles 2   & #“/ Pascal Symbol 190 peptide 191, 210 Percentage Composition 191 Periodic law 192 periodic table 192, 198 Petroleum 193, 194 phase diagram 194     #“$ phenylhydrazones. 131   { #“$ Phosphine 196     ‰$ Phosphorus (III) Chloride Oxide 199 Phosphorylation 199 photographic emulsion 6 Photosynthetic pigments 200 Physical chemistry 201 Pipette 202 Plank constant 202 plants suffering loss of water 1 Plastic 203 Platinum 203 platinum electrode 214 Polarization 203, 204   /$ polybrominated diphenyl ethers (PBDEs) 32 Polycarbonate 206

Index

Polychlorinated Biphenyl (PCB) 206 Polypropene (Polypropylene) 207 polysaccharides 113   ˆ   5 ˜=/!   $$ potential of hydrogen. 194 Potentiometric Titration 208 poured in water 4    ‰$    {   #‰$ producing ethyne 226 Protein denaturation. 77    $Ž

Q Qualitative Analysis 213 Quantum (Plural Quanta) 213 Quinoline (C9H7N) 214 Quinone 214

R € [  #$ € #$ radiation of adequately high energy 141 €  >#$ €   #$ €    #$ Radiolysis 216 Raschig Process 216 Rate of Reaction 217 Rayon 217 reaction 144 Reactive Dye 218 Rearrangement 218 reconstitute oxaloacetate 147 €Q#ž red pigments 44

281

reducing transpiration 263 Reduction 219 ˆ?Žž Relative Atomic Mass 219 Relaxation 220 Resolution 220 Resonance (Mesomerism) 221 Respiration 10, 18, 221 Retrosynthetic Analysis 222 Reversible Change 222 € 5&$}#/|$=" RNA (Ribonucleic Acid) 224 Roentgen 224 €$

S Sandwich Compound 226 Saturated Solution 227   >  $! Second-Order Reaction 228    $" Semicarbazone 228 Serotonin (Hydroxytryptamine) 229 Side Reaction 229 Siemens (mho) 230 Single-Cell Protein (SCP) 231 SI unit 230, 238 SI unit of energy and work 144 Q`  ˆ?Ž‰ skins of animals 114 sodium chloride 84 Solid 232 Solubility 232 Solvent 233 Sorbitol 233 sound waves lose energy 2   > "Ž Q€    "‰ Spectrometer 234

282

Key Concepts in Chemistry

Q  "$ Q5 Q ="$ Stabilization Energy 236 standard temperature 236 strained ring mixtures 26 substance at absolute zero 268 sugar 113, 114, 117, 118, 119 Sulfuric acids 4 Sulphur and phosphorus, 174 symbol 267   $$  $  "$

T techniques of aldehyde fusion 29 Terylene (Trademark 246 tetrachlorodibenzo-p-dioxin (TCDD) 82 tetrachloromethane (CCl4) 122 Tetrapyrrole 247 thermodynamic process 9 thermodynamic properties 7 Thermodynamics 247     $ Thiazole (C3H3NS) 248    5=‰ž Thiophene (C4H4S) 248 Titration 249 Tracer 249    $/ transport hydrogen atoms 171      $/ tripeptide of cysteine 117  $# tubular structure 171 5\& |=$

U ·&$‰ unit of energy 36 Unit Processes (Chemical Conver =$‰ · [*&$‰ ·  &  $‰ · Y    €$$ ·$$   $$

V * ƒ  $Ž *  $! *  [  $! variation in temperature 124 various viscous liquids 182 varnishes. 264 * $ž > $" * $ž * &$“ Volt 260 Volumetric Analysis 260 Vulcanite (Ebonite) 260 Vulcanization 261

W Water (H2O) 262 Water molecules. 262 water of crystallization 88 water-soluble vitamin 31 Wavelength 263 wavelengths of radiation 7 Wave Number 263 White Spirit 264 Wurtz–Fittig reaction 264 Wurtz Reaction 264

Index

X ®  Ž$ ?   Ž$ ®\   Ž$ x-ray 266 X-Ray Diffraction 266 X-ray of palm 266

Y yellow crystalline 198, 201

283

Ylid (ylide) 267 yoctometer 267 Yotta 267

Z Zeisel Reaction 268 Zeolite 268 Zero-Point Energy 268 Zwitterion (Ampholyte Ion) 269

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