HAZARDOUS MATERIALS CHEMISTRY. [3 ed.] 9781284041996, 1284041999

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TH I R D E DI T ION

Hazardous Materials Chemistry Armando S. Bevelacqua, RPM, BS Laurie A. Norman, PhD

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General Manager and Executive Publisher: Kimberly Brophy VP, Product Development: Christine Emerton Executive Editor: Bill Larkin Senior Development Editor: Alison Lozeau VP, Sales, Public Safety Group: Matthew Maniscalco Director of Production: Jenny L. Corriveau Production Editor: Dan Stone VP, Manufacturing and Inventory Control: Therese Connell Manufacturing and Inventory Control Supervisor: Amy Bacus Composition: S4Carlisle Publishing Services Library of Congress Cataloging-in-Publication Data Names: Bevelacqua, Armando S., 1956- author. | Norman, Laurie A., author. Title: Hazardous materials chemistry / Armando S. Bevelacqua and Laurie A. Norman. Description: Third edition. | Burlington, MA : Jones & Bartlett Learning, [2018] Identifiers: LCCN 2018005730 | ISBN 9781284041996 Subjects: LCSH: Chemistry. | Hazardous substances. | Chemicals--Safety measures. Classification: LCC QD33 .B48 2018 | DDC 604.7--dc23 LC record available at https://lccn.loc.gov/2018005730 6048 Printed in the United States of America 22 21 20 19 18 10 9 8 7 6 5 4 3 2 1

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BRIEF CONTENTS SECTION 1  Guiding Chemical Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 1  Applied Scene Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Chapter 2  Properties and Toxicology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Chapter 3  The Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Chapter 4  Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Chapter 5  Intermolecular Interactions and Predicting Physical Properties . . . . . . . . . . . . . . . . . . . . . . . 96 Chapter 6  Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Chapter 7  Reaction Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 SECTION 2  Chemical Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Chapter 8  Inorganic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Chapter 9  Organic Compounds: Hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Chapter 10  Substituted Hydrocarbon Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 SECTION 3  Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Chapter 11  Tools of the Trade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Chapter 12  Risk-Based Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 Chapter 13  Weapons of Mass Destruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 Chapter 14  Science Officers’ Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 Appendix A  FESHE Correlation Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

CONTENTS SECTION 1  Guiding Chemical Principles . . . . . . . . . . . . . . . . . . 1 Chapter 1 Applied Scene Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Benner’s Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Behavior Event: Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Behavior Event: Breach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Behavior Event: Release. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Behavior Event: Engulfing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Behavior Event: Impingement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Behavior Event: Harm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Units of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Converting Between Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Scientific Notation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Significant Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Scientific Method and Decision Making. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Scientific Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Decision Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Chapter 2 Properties and Toxicology. . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Properties of Matter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pure Substances Versus Non-Pure Substances . . . . . . . . . . . . . . . . . . . . Physical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pH Ion Scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Toxicology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Routes of Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Types of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Exposure Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reducing Potential Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Toxicological Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reactions in the Body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Testing for Exposure Effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24 25 25 26 27 32 35 36 37 37 38 38 41 41 42

Chapter 3 The Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Structure of Atoms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Periodic Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Families and Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50 53 53 54 54

Electronic Structure of the Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electronic Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Periodic Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bonding Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alpha Particles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Beta Particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gamma Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Understanding Radioactivity and Radiation Absorbed Dose. . . . . . . . . . Radiation Hazard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Protective Action Guides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stay Time Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

56 57 60 63 64 67 68 69 69 70 71 72 73

Chapter 4 Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Valence Electrons and Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Ionic Bond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Covalent Bond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ionization of Molecules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lewis Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rules for Drawing Lewis Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . Resonance Structures and Formal Charge. . . . . . . . . . . . . . . . . . . . . . . . Valence-Shell, Electron-Pair Repulsion (VSEPR): Predicting Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Molecular Shape and Polarity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

80 81 81 81 82 83 85 86 86 88 90 92

Chapter 5 Intermolecular Interactions and Predicting Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

96 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Intermolecular Forces in Pure Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Dispersion Forces (Van der Waals). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Dipole-Dipole Interactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Hydrogen Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 The Ionic Bond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Physical Properties of Pure Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Phases of Matter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Boiling Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Vapor Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Phase Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Intermolecular Forces in Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 The Ion-Dipole Interaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Energetics of Solution Formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Physical Properties of Liquid Solutions. . . . . . . . . . . . . . . . . . . . . . . . . 108 Vapor Pressure Lowering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Boiling-Point Elevation and Freeze-Point Depression. . . . . . . . . . . . . . 108

Contents

Chapter 6 Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction: Materials That Are Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Kinetic-Molecular Theory of Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boyle’s Law: The Pressure-Volume Relationship. . . . . . . . . . . . . . . . . . Expansion Ratios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Charles’ Law: Temperature Volume Relationship . . . . . . . . . . . . . . . . . Avogadro’s Law: The Relationship Between Quantity and Volume . . . . The Ideal Gas Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gas Laws Revisited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boyle’s Law Revisited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Charles’ Law Revisited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Relationship Between Temperature and Pressure . . . . . . . . . . . . . . . . . . . . Elevated Temperatures and Dangerous Conditions. . . . . . . . . . . . . . . . The Combined Gas Law. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Molar Masses and Gas Densities and Molecular Speeds. . . . . . . . . . . . . . . . . . Catastrophic Release of Condensed Liquefied Gases: Jack Rabbit Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dalton’s Law of Partial Pressures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

114 115 115 116 117 117 118 119 120 120 121 121 122 123 123 124 125

Chapter 7 Reaction Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coefficients Versus Subscripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Law of Conservation of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enthalpies of Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . State Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bond Enthalpies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rate of Reaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Activation Energies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Types of Chemical Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Precipitation Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid/Base Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oxidation/Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

130 131 131 132 132 133 133 134 134 135 135 136 138 141

SECTION 2  Chemical Nomenclature . . . . . 149 Chapter 8 Inorganic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Icons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Binary Compounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metal Oxides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

150 151 151 152 154

Inorganic Peroxides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metal Hydroxides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hydrates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Polyatomic Ions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OxySalts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OxyAcids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Binary Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Binary NonSalts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nonmetal Oxides (Fire Gases) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen-Containing Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . .

v

155 156 156 158 158 159 160 161 163 163

Chapter 9 Organic Compounds: Hydrocarbons. . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organic Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alkanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alkenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alkynes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Review of General IUPAC Naming. . . . . . . . . . . . . . . . . . . . . . . . . . . . Cyclo Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aromatics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Branching and Its Effects on Physical Properties. . . . . . . . . . . . . . . . . . . . . . . . Petroleum Derivatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

172 174 174 174 175 179 181 181 182 183 185 187

Chapter 10 Substituted Hydrocarbon Compounds. . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Halogenated Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Halons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methyl Chloride (Chloromethane). . . . . . . . . . . . . . . . . . . . . . . . . . . . Methylene Chloride (Dichloromethane). . . . . . . . . . . . . . . . . . . . . . . . Trichloromethane (Chloroform). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tetrachloromethane (Carbon Tetrachloride). . . . . . . . . . . . . . . . . . . . . Oxygen-Containing Functional Groups: Alcohols, Phenols, and Their Sulfur Analogs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alcohols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alcohol Analogs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phenols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sulfur Analogs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thiols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Functional Groups with a Carbonyl Carbon. . . . . . . . . . . . . . . . . . . . . . . . . . . . Aldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ketones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ester. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organic Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ethers and Epoxides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ethers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organic Peroxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

194 196 196 197 197 197 197 197 198 198 199 200 201 201 201 202 204 204 205 206 206 208

vi

Contents

Nitrogen-Containing Functional Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diazonium Salts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mustard Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitro Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitriles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Isocyanates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

208 208 210 210 210 211 211 212 212

SECTION 3  Application. . . . . . . . . . . . . . . 223 Chapter 11 Tools of the Trade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

224 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Tools of the Trade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Placarding and Containers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 The Street Approach to the DOT Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Class 1: Explosives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Class 2: Gases and Class 3: Flammable Liquids . . . . . . . . . . . . . . . . . . 229 Class 4: Flammable Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Class 5: Oxidizers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Class 6: Poison. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 Class 7: Radioactive Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Class 8: Corrosive Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Class 9: Miscellaneous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 Resource and Referencing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Emergency Response Guidebook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 NIOSH Guide Book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Safety Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 General Monitoring and Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Detection, Monitoring, and Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . 244 Current Detection Technologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246

Chapter 13 Weapons of Mass Destruction. . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Activity and Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Precursors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triage Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Corrosive Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Activity and Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Precursors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Asphyxiants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Activity and Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical Precursors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Incapacitating Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Activity and Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Riot Control Agents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lacrimators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vomiting Agents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Use of CWAs or Weapons of Mass Destruction. . . . . . . . . . . . . . . . . . . . . . . . . Philosophy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tactics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Physiology and Medical Ethics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Biological Agents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 14

Chapter 12

Science Officers’ Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Risk-Based Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . History of Models for Hazardous Materials Incidents. . . . . . . . . . . . . . . . . . . . . DECIDE Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General Hazardous Materials Behavior Model. . . . . . . . . . . . . . . . . . . . Using Detection Devices in Risk-Based Response . . . . . . . . . . . . . . . . . . . . . . . RBR Profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detection of Unidentified Materials and Sampling Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Systematic Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analyze the Hazard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan the Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Implement the Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Evaluate Progress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

286 287 288 288 289 290 290 290 290 290 290 292 292 292 293 293 294 294 295 295 295 296 296 296 296 297 297 297 298 298 298 300

262 263 263 263 264 265 266 267 269 269 272 274 281

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Decision-Making Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effective Communication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applying Knowledge at a Hazardous Materials Event. . . . . . . . . . . . . . . . . . . . A.P.I.E. Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analyze . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Implementation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparing the Decision-Making Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tactical Worksheet Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scene Considerations and Resources . . . . . . . . . . . . . . . . . . . . . . . . . . Monitoring and Detection Equipment . . . . . . . . . . . . . . . . . . . . . . . . . Environmental Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

304 305 306 307 308 309 310 310 310 311 311 312 312 313 313

Contents

Understanding Tactical Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absorption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Damming, Diking, and Diverting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Retention. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vapor Dispersion and Suppression. . . . . . . . . . . . . . . . . . . . . . . . . . . . Pressure and Containment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Personal Protective Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decontamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

317 317 318 318 318 321 321 322

vii

Appendix A FESHE Correlation Guide..................................................... 329 Glossary.............................................................................................................. 333 Index................................................................................................................... 341

ABOUT THE AUTHORS Armando S. Bevelacqua is a 37-plus-year veteran of the fire service and the recipient of the 2010 “In the Zone Award” and the “Level A Award” for leadership, service, and support in education of the hazardous materials first response community, and the Dieter Heinz 2016 instructor of the year award. Retired from City of Orlando Fire Department, Orlando, FL, where he served as Chief of Special Operations, Homeland Security, EMS, and USAR, Armando lectures to fire departments throughout North America, Canada, and Europe. Chief Bevelacqua serves on several federal, state, and local committees. He holds membership to the Inter-Agency Board (IAB) for Training and Exercise member to the NFPA 472, 473, and 475 Technical Committees, along with representation on the American Society for Testing and Materials (ASTM) standards development committee for emergency response. Chief Bevelacqua has assisted in the development of standards and protocols, such as with the Rocky Mountain Poison Control for the development of a standardized medical protocol for weapons of mass destruction (WMD) event and for the State Department for WMD training of embassy delegates. His latest endeavor is to create educational videos for the first response community, educating new and seasoned responders to the ever-advancing technologies that are entering the first response arena.

Laurie A. Norman is an Associate Professor in the Department of Science and Mathematics at the Massachusetts Maritime Academy in Buzzards Bay, MA, where she teaches chemistry classes. Her favorite class to teach is Organic Chemistry/ The Chemistry of Hazardous Materials, a required course for students majoring in Emergency Management and Marine Safety & Environmental Protection. She earned her bachelor’s degree in chemistry at Bowdoin College and her Ph.D. at the University of North Carolina at Chapel Hill. Upon completion of her studies, she worked as a research scientist for Honeywell’s Consumer Products Group, where she formulated products used in the car care industry. She is listed as an inventor on four patents related to her work in this field. She taught at Western Connecticut State University and Bridgewater State University before accepting her position at Massachusetts Maritime Academy.

ACKNOWLEDGMENTS Perhaps the hardest part of writing a book is writing the acknowledgments. It’s not about the collection of facts that the manuscript offers but rather a collection of ideas and thoughts, and the ideas and concepts that are grown out of many discussions. It is a culmination of the years of study and, more important, the instruction of these concepts, the scenes that we have been involved with, and the people that we have interacted with. It is the teaching of students, discussion groups, conferences, and of course the bar napkins (many bar napkins) that really, truly provides the basis of a book like this. When we as responders started our journey into the world of hazmat response and started to learn the basics of chemistry, we really did not pay much attention to the nuances that are embedded within the chemistry discipline. We soon found out that some of the calls that we go on are beyond the basics of what we learned in our initial hazmat class, and therefore found ourselves in a chemistry course that was hopefully geared towards emergency response to answer our questions. Hopefully; but most of the time the class was geared towards a chemistry major or some life science discipline, and not emergency response. It is for this reason this book was written, and it is for all of our students past, present, and future who will take the time to read and learn from each other’s experiences. This concept of street-level application within this book, sprinkled with scientific fact and chemical theory along with the experiences of many, has not come just from us, the authors, but rather is truly a collective effort of extremely smart and experienced individuals who make up the hazardous materials response and scientific community. It is to this group, the hazmat responders at large and the traditional chemists, who have contributed to this body of work over the many years of response. Over the years, my acquaintances have become friendships, and it is from here that the opportunity to learn, discuss, and more importantly hone the body of knowledge that we understand, as hazardous materials responders, becomes contributions to this discipline and the understanding thereof. We cannot discount the thousands of students that we have had over the years; for it is for these responders (and future responders) that this book was started, and it is for this reason that several iterations of this book have occurred over the last 20-plus years and will continue into the future. So, I would like to start with a heartfelt thank you to my coauthor Laurie. Over the course of this development, reorganization, and writing, she has taught me that units matter, and that the descriptive terms must be precise. This is something that the fire service is very lazy with but means much to a chemist. I must say it has been a great pleasure to know Laurie and work with her on this project and truly look forward to our next project. It is the many conversations surrounding the chemistry and the field application, how we in the fire service view a topic and how we think. Your questioning and degree of inquisitiveness are something to be admired. I will truly miss these lengthy, sometimes hours on end discussions. Thanks to you, Laurie, for

putting up with my street-level look at the chemistry and lack of unit discipline; I will try to be better at that! I would be remiss if a few of those that have contributed their ideas and thoughts to this work are not mentioned and greatly appreciated; including Ludwig Benner Jr.—having lunch with Ludwig on several occasions is a remarkable experience, and we thank him for his initial review of the manuscript and insightful forward. I am grateful for Ludwig’s words of encouragement. Thank you, sir. Richard Stilp, a close friend for over 30 years; we worked together on the original heavy rescue with Orlando Fire Department as the first HazMat Medics. A call out to his friendship and foundational research for the chapter case studies; thanks Rick. Eugene Ngai—introduced through a mutual friend, Eugene is the go-to guy when it comes to compressed gases, the inventor of many tank coffins, and tactics used today. Eugene has been an invaluable consult on many occasions and his input to the gas chapter was instrumental. Chris Hawley, a friend and a colleague. Thanks for his input on the risk-based response chapter. Chris helped us get through some truly serious writer’s block; thanks for the help, my friend. It is greatly appreciated—a little payback from years past. Glen Rudner, someone we have known for a long time; thanks for the review of select chapters concepts and ideas. As always, your insight to field work and application was much needed during the long hours of writing and research. Matt Marshall, with his input about preplanning and the tools that can assist with that process; thanks for your input.

Richard Stilp RN, BA, MA Fire Chief St Cloud, FL

Eugene Ngai BS, MEng President Chemically Speaking LLC

Chris Hawley Glen Rudner Hazardous Materials Compliance Officer Norfolk Southern Railway

Matt Marshall Battalion Chief Cape Coral Fire Department, FL Last but not least is my wife, Michelle, for the times that we didn’t go to the beach, or take that bike ride, or take a walk; thanks for putting up with my obsession to get this edition done and the long hours on the phone or in meetings. Now that it is done, let’s go to the beach and take that long walk! Dedication to my littles—Noah, Declan, Aria, Theo, and Elle. Hopefully, one day they will read this book! Armando S. Bevelacqua

x

Acknowledgments

First and foremost, I would like to thank my husband, Mark Norman. If it were not for Mark and his roles at companies that provide emergency responders with advanced chemical detection technologies, I would never have met Toby Bevelacqua. My career path eventually led me to the Massachusetts Maritime Academy, a state college where some of my students are interested in careers within emergency response. I owe a huge amount of gratitude to Toby. When tasked with teaching the chemistry class most relevant to Emergency Management majors, I learned from him what the most important chemical principles were for the emergency responder. My interactions with him have greatly improved my understanding, not only of “street chemistry,” but also of foundational chemical principles, because thinking about the situations faced by the emergency responder allowed me to apply basic chemical principles to a greater number of applications. Although most of my lengthy chemistry discussions involving hazardous materials response were with Toby, there were many other interactions that have increased my understanding

of this field. Talking and taking classes with Chris Weber, Rick Dufek, Tony Mussorfiti, Chris Hawley, Glen Rudner, Dave ­Matthew, Kristina Kreutzer, Michelle Murphy, Marty Greene, Frank ­Docimo, Pauline Leary, along with others, helped me to grow in my understanding of emergency response. Finally, I would like to thank my students and colleagues at the Massachusetts Maritime Academy. I would like to give a special thank you to Michael Montigny. More than once, he came to my office looking for coaching in chemistry only to find me trying to take a photograph for this book. He ended up taking the best shot. Two photographs taken by him are included in this book. I would also like to thank my colleague in physics, Professor Matthew Loomis, for reviewing the sections of this book that are related to radiological materials, a subject I am deficient in. Like Toby, I would like to dedicate this work to my little ones (or maybe not so little anymore). They’re both going to make a positive difference in this world in their own way. Andy and Dan: Mom loves you so much, and she’s so proud of you. Laurie A. Norman

Acknowledgments

Reviewers Bill Arsenault Idaho Falls Fire Department Nampa, Idaho

Lieutenant John C. Berna Fire Department, City of New York New York, New York

Andrew Byrnes, MEd, EFO Utah Valley University—Emergency Services Provo, Utah

Deputy Chief Jim Campbell Pike Township Fire Department Indianapolis, Indiana

Daniel Casner CalOES/CSTI Upland, California

Tobias Frost Lafayette Fire Department  Lafayette, Indiana

Joseph Guarnera Hazmat Specialist/Branch Manager USAR Massachusetts Task Force One Beverly, Massachusetts 

C.J. Haberkorn Denver Fire Department Denver, Colorado

Chief Larry Hansen Oklahoma City Fire Department Oklahoma City, Oklahoma

Michael E. Hanuscin, BS, NREMT Battalion Chief, Charleston Fire Department Charleston, South Carolina

Gordon Haynes South Plains College, Fire Technology Program Lubbock, Texas

Chad Landis  Chief of Training  Town of Ball Fire Department Ball, Louisiana 

Ruben Lopez, FF/AEMT Lieutenant, Bulverde Spring Branch Fire & EMS Spring Branch, Texas 

Mathew Marshall  Battalion Chief, Cape Coral Fire Department Cape Coral, Florida

Jim O’Connor Columbus Ohio Division of Fire Logan, Ohio

Kevin O’Hara, MS, EMT-P Stony Brook Medicine Suffolk Community College New York, New York

Michele Parsons Cumberland County Department of Public Safety Carlisle, Pennsylvania

Sean F. Peck, MEd, FO, NRP Arizona Western College Yuma, Arizona

David Probo Spartanburg County Fire Marshal’s Division Spartanburg, South Carolina

Louie Robinson HealthNet Aeromedical Service Charleston, West Virginia

Captain Rich Saalsaa Philomath Fire and Rescue Philomath, Oregon

Robert Salvesen FDNY Hazmat 1 Specialist, Co-host of The HazMat Guys Podcast East Meadow, New York

Robert “Les” Smith Charleston Fire Department Charleston, West Virginia

Allan Wickline  Chief, Allegheny County Haz-Mat 440 Penn Hills, Pennsylvania

Travis Witt St. Petersburg Fire Rescue St. Petersburg, Florida

xi

FOREWORD Many years ago, while with the National Transportation Safety Board (NTSB), I investigated a hazardous materials accident in which the training officer of a large fire department was killed by a sudden explosion. Our findings—hazardous materials training was seriously flawed at the time—had a profound effect on me personally. The closer I looked, the more deficiencies I discovered, including study resources. It wasn’t long before I was able to engage others to look with me for ways to reduce risks to responders and the public in these emergencies. The efforts of many have contributed to a dramatic reduction in those risks over the years, along many avenues. As I reflect on the changes, it is gratifying to see how far the field has progressed, in large measure because of improved approaches, study materials, and training. However, hazardous materials or “hazmats” as they are widely known, remain a large part of our everyday lives and economy. They are made, stored, transported, and used throughout our society. Occasionally, hazmats still become involved in unintended and sometimes dangerous situations. When such situations arise, emergency responders are still expected to cope with any threats they pose and produce the safest possible outcomes. Because of the variety of materials and almost infinite variety of circumstances in which they can become threats, coping with them successfully in any crisis can be a daunting challenge for emergency responders. These circumstances actually pose two kinds of challenges for responders: planning and preparing for responses to hazmat incidents, and reacting to hazmat threats in incidents when they occur.

One task common to both challenges is the need to predict what the hazardous material is likely to do next in a specific crisis and the resultant threats that will pose to exposed people, property, and the environment. That task requires special knowledge about hazmat chemistry and skills in applying that knowledge to help ensure successful response decisions and outcomes. The hazmat knowledge required includes hazardous material names and categories; their nature and properties; characteristic behaviors when they are confined, stressed or released, or come in contact with nearby exposures; and the kinds of harm they can inflict. The required skills for applying that knowledge in specific situations mature with study, training, and experience. This involves learning the language of hazmat chemistry, the principles for application of hazmat knowledge, and the relevant tools in specific evolving situations to help define and deal realistically with the changing threats and risks. New responders keep entering the service. This book will help all responders acquire or refresh the knowledge and skills needed to meet both planning and response challenges successfully. I endorse its careful study without reservation and commend Toby and Laurie for creating this resource to fulfill an ongoing need.

Ludwig Benner Oakton, VA

INTRODUCTION Some 40 years have passed since the inception of hazardous materials response. In the early days, a general understanding of commonly used chemicals and their chemical and physical properties was the extent of the responder’s education. Back then, there were no training manuals, no training classes, and few experiences to draw from. We were writing the tactics as we went along. In the early days, commanders wanted us to memorize these common chemicals so that we could quickly attack a problem involving one of them. Since these early days, the frequency of hazmat incidents has increased, and we also learned that a quick attack is not always the best approach. A more systematic approach was reinforced through the work of Ludwig Benner in the 1970s. With the increase of events and because of limited education, fire fighter injuries and deaths began increasing in the emergency response community. The importance of chemistry classes was starting to be recognized, along with the importance of understanding air monitoring, mitigation strategies, personal protective equipment usage, decontamination strategies, and so on. With this influx of education, one component that should be a part of the education cycle is a street-level application of well-understood scientific principles. For many classes and presentations, this is not the case and hence why this book was written. It is this concept that has remained in the forefront during the long hours of research and writing of this text. During emergency response situations, we are technicians. We act as the bridge between what is known in the chemical industry and what happens when things go badly. When these two worlds collide, the technician and the scientist must use a common language. We also see this in the emergency medical services (EMS). Lifesaving techniques are learned, but more important, it is when a common language between the technician and the physician are used that rescue situations are most effective. Hazmat response is no different than EMS, in that you have to speak and converse with the chemist in the language of chemistry for the situation to be resolved most effectively. It’s not that you will know or understand chemical principles at the same level as the chemist, but rather you are the ears and eyes of the scientist who is not on scene. You must be able to identify and communicate the issues effectively to the chemist for

the best advice when an incident occurs. That is the perspective from which this edition was written; from both the eyes and ears of the first responder and the eyes and ears of the chemist. It is a melding of the two worlds—the principles of chemistry with the hard facts of emergency response. In this third edition of Hazardous Materials Chemistry, we have broken down the discipline into three distinct areas of study. Within each chapter, you will find an incident that highlights the principles that are taught within that chapter and a way to look at the chemistry through the lens of emergency response. The first section contains the guiding chemical principles that surround anything you do in chemistry and thus emergency response. These are the foundational principles from which strategy and tactics should originate. We spend time in this area to give you, the reader, the facts and principles of chemistry and to show you how to apply these within the emergency response arena. In section two, we explore the nomenclature of chemicals and the associated hazards with these families. We have placed these into three categories for naming. Each chapter provides the emergency responder with the background to recognize a chemical name and then translate that name into potential hazards, for the name of the chemical can provide clues to your incident. Additionally, if you know the hazards, then during detection and analysis, you can work backward and come up with a potential list of chemical families that may be the culprit. Within these chapters, we have provided practical application of the guiding principles and in some cases a glimpse into the third section, which is application. In the third section, we review the chemistry in terms of applications, because hazardous materials response is chemistry gone bad. It is, for many within our communities, the day that is considered to be not so good. Here we explore the fundamentals of strategies, recognition, and initial detection and how they relate to the chemical principles. We combine the first two sections into practical application of the principles and nomenclature. As with any book, this is only the beginning of your studies; it is the foundation of what is termed hazardous materials response and provides a direction towards incident termination. This is hazardous materials chemistry.

© sandyman/Shutterstock, Inc.

SECTION

Guiding Chemical Principles CHAPTER 1 Applied Scene Chemistry CHAPTER 2 Properties and Toxicology CHAPTER 3 The Atom CHAPTER 4 Bonding CHAPTER 5 Intermolecular Interactions and Predicting Physical Properties CHAPTER 6 Gases CHAPTER 7 Reaction Basics

1

CHAPTER © Aiken County Sheriff's Dept/AP Photos.

1

Applied Scene Chemistry LEARNING OBJECTIVES Upon completion of this chapter, you should be able to: • • • • • • • • • •

Summarize observations through the use of appropriate measurement. Differentiate between the behavior model events. Describe the GEneral hazardous materials Behavior MOdel (GEBMO). Integrate GEBMO observations such as thermal, radiological, asphyxiants, chemical, etiological, and mechanical (TRACEM) behaviors with chemical/physical properties. Compare the units of measurement. Recognize error in measurement. Describe the use of the scientific method. Describe the Systeme Internationale (SI) units of measurement. Describe standard temperature and pressure (STP). Identify the use of scientific notation.

NFPA Citations and Competencies Citation or Competency Heading

NFPA 472 Reference

Risk-Based Response

3.3.57, 7.1.11, 11.1.2.2, 11.2.1, 11.3.2.1, A.5.2.4 (4), E.1.3

General Behavior Model

9.3.2.2, 20.3.2 (9), A.5.2.3 (3)

General Behavior Model – Thermal

9.3.2.2, 20.3.2 (9), A.5.2.3 (2), A.5.2.3 (3), A.5.2.3 (7)

General Behavior Model – Radiological

3.3.68.1, 5.2.1.6.6, 6.2.3.1, 6.11.2.2, 7.3.2.2, 8.2.2, 18.4.1, 20.2.8, 20.4.1, 24.2.1, A.5.2.3 (3), A.5.2.3 (7), A.5.3.3 (1)

General Behavior Model – Chemical

3.3.16, 3.3.58, 4.4.1, 5.2.1.1.2, 5.2.1.6.2, 5.2.1.6.3, 5.2.2, 5.2.3, 6.4.5.1, 6.11.2.2, 7.2.2.2, 7.2.4

General Behavior Model – Etiological

6.2.3.1, 7.3.2.1

General Behavior Model – Mechanical

3.3.21, 5.2.3, 6.11.2.3, 7.3.2.2, 11.3.3 (2), 13.2.1, A.4.4.1 (3)(C), A.5.2.3 (3), A.5.2.3 (7), A.8.3.4.5.5 (2), A.11.3.3 (2)

Case Study On February 22, 1978, at 10:30 pm, 24 freight cars derailed in the downtown corridor of Waverly, Tennessee. Weather conditions that night were a light snow on the ground and temperatures in the mid-20s Fahrenheit. The Louisville and Nashville railroad was traveling through Waverly at the speed limit of 35 mph. The rear brakeman, who was in the front of the train, noticed a brake application that was an automatic application for Courtesy of Bill Hand. emergencies. He saw that the train had separated when cars 17 through 39 had derailed. Included in the derailed set of cars were two liquefied petroleum gas (LPG) tank cars, UTLX–83013 and UTLX–81467, respectively. Upon inspection, neither tank car displayed leaks, but these cars were heavily damaged. It was declared that the tank car would be moved so that the contents of the cars could be placed into highway trailers. Several freight cars obstructing the LPG tank cars were moved, and a cable sling was placed on one end of the LPG tank car with the other end used as a pivot point. A wooden support was used at the end in which the cable was attached. The other cars were moved in a similar fashion. Relocations of the tanks were completed by 2:15 pm on February 23. Gas monitoring showed no indication of a leak. The wrecking crew continued to work to remove cars and wreckage, which concluded at 8:00 pm on February 23. The tank car at the south end of the incident, because of the level of damage to the container, was the first car to unload to highway tankers. The second LPG tank car was scheduled for unloading the next day on February 24. By 1:00 pm on February 24, the highway tanker arrived for the transfer. On February 24, at approximately 2:53 pm, the north car ruptured and allowed LPG into the environment; ignition occurred a few moments later from an undetermined ignition source. Weather temperature conditions by this time had increased into the 50s Fahrenheit without cloud cover. Using the principles set forth in this section, answer the following questions: 1. What has happened? 2. What will or could happen? 3. What can you change?

Introduction When responding to a hazardous materials event, whether a frequent occurrence or an event that is more unusual, it is important to have a systematic approach. The diversity of the chemical threats that may be encountered and the variety of tools at your disposal for detection and monitoring indicate a need for specialized training. This chapter will look at the tactical level decision-making process or what is currently being referred to as risk-based response (RBR). RBR is a practical approach, utilizing the appropriate level of resources for the hazard that is presented, and it applies to a variety of situations and environmental conditions across the hazardous materials response spectrum Figure 1-1 . It is useful to implement this method of response due to the financial constraints of the emergency services, but more important, it saves time and other valuable resources. Today, our society demands answers and quick responses to emergencies. Our communities are burdened with ever-­ increasing traffic loads, which in turn demand a quick and efficient “cleanup” of the event. By developing and designing an approach toward this quick and efficient method of looking at risk and controlling the hazard, you have further educated your forces to deliver a controlled and informed response. Many have stated that RBR is something that is directly against the associated standards that hazardous materials (hazmat) response embraces. However, if you look deeper at this type of response, you see that the intent of the standards and regulations are covered in greater detail with this type of response. When hazmat events occur, a cookbook actionable approach cannot be made. Instead, a process that is systematic toward mitigating

Figure 1-1  Hazardous materials events can be complex; however, understanding the science allows the responder to utilize only the equipment and resources required to manage the response. © Ric Feld/AP Photos.

actions is needed. Additionally, RBR provides the responder the framework by which an informed decision can be made. RBR truly gives new meaning to the recognition-primed decision-making (RPDM) process. RPDM is a concept that

4

Hazardous Materials Chemistry, Third Edition

identifies what you think by matching previous events to the currently presented problem. If the situation has not been experienced previously, the decision may not be the best solution. By applying a well-developed RBR system, the first-response community has been provided “movie” scenarios from which one can draw from (this topic will be explored in further detail in Chapter 12, Risk-Based Response). RBR conserves the resources applied to an event while avoiding unnecessary risk and looks at options that are based in factual information, thus giving an informed decision-making process. Any discussion on hazardous materials chemistry should begin with a conversation on the critical information, i.e., the recognition and the prediction of harm. In order to do this, responders must be able to utilize data from a variety of sources, each time evaluating the validity and authenticity of that information. Therefore, it is the management of this information that becomes the challenge. One should look at an incident and prioritize what you need right now, what can be done a half hour from now, and what can wait an hour or two. In other words, a progression of needs should start to develop, based upon the known and the anticipated chemistry. In prioritizing these challenges, the responder should be thinking and anticipating: • What has happened? • What will or could happen? • What can I change, now and 30 minutes from now? It is with the knowledge of chemicals and their reactions and interactions that you can anticipate what may happen, which is the basis of this discussion and the point behind learning street-level chemistry. Years ago, Ludwig Benner, an engineer by trade, discovered that all events—all hazmat events—have a distinctive pattern, and it is up to the responder to recognize this pattern and act accordingly. Benner proposed that people see and manage events as little movies based upon previous experiences. Everyone has had an experience in which common elements from a previous experience are recognized. A current action or experience can mimic the last experience. If the last time the outcome was positive, then you move toward that action, which was previously done, with positive results. However, an analysis of the previous experience along with the present one must be done to insure that these are the same and that a simple nuance is not the difference, which could provide a negative outcome (see Chapter 12, Risk-Based Response). Therefore, in order to organize these recognizable patterns, Benner came up with a mnemonic that organizes the potential harm responders may encounter. This became the TRACEM acronym for thermal, radiation, asphyxiation, chemical, etiological, and mechanical harm. Associated with the event model, responders now have a structure of events. It is important to remember that every hazmat incident has three basic elements: 1. Product 2. Container 3. Environment

It is these three elements that formulate the incident and the events that either have or will unfold. It is up to the first responder to identify these elements using the GEneral hazardous materials Behavior MOdel (GEBMO) and TRACEM to see where you are in the event timeline and what can you do to prevent a negative outcome. It is the interrelationship between the product, the container, and the environment that either maintains the hazardous substance in the transportation vessel or allows it to leak out. This chapter is a detailed discussion on the issues of evaluation of risk, measurement, and chemical, physical, and toxicological studies.

Benner’s Model GEBMO is a description of a sequence of events that occurs at all hazardous materials incidents. It enables us to visualize the potential probabilities. Combine this model with the knowledge of chemistry and understanding of your surroundings and you have all three factors that affect the event: product, container, and environment. Benner’s model identifies the event type with potential principles to change outcomes Table 1-1 . In all states of matter, energy is stored within the bonds and between molecules of the material. This stored energy may be released in a hazardous manner under certain conditions. These conditions, associated with the container and the environment, are what are observed to predict event outcomes. It is important to understand that each factor has a distinct relationship. Product deals with the chemical, chemical family, and potential chemical hazards. It is the state of matter or the inherent conditions of the chemical that give rise to some of the hazards at an incident. Chemicals may exist in three common states of matter: solid, liquid, and gas. These phases all behave very differently. The state of matter is an important factor for the first responder’s assessment. It is important to understand the state of matter and how it relates to the container and the environment that gives rise to the potential hazards. Compare this with the environment, for example, fire impingement on a container holding a liquefied gas, and you can predict the outcome. Therefore, understanding the product’s state of matter, chemical family, and the chemical hazards of that family has a direct bearing on the visual identification of where you may be in the GEBMO, and the potential hazards that can occur. When you look at containers, look at each container with the GEBMO in mind. That container may be a compressed gas cylinder found in an auto repair shop or a tanker traveling down the interstate. Understand that rooms within buildings can also present a distinct set of circumstances, and thus can act like and should be thought of as a container. The state of matter and the potential hazards can be predicted when given a set of environmental conditions. Product and container are not mutually exclusive, but rather if one understands the product, then one will understand how it interacts with the container. Understanding this simple fact will lead the responder to a reasonable understanding of the air monitoring data gained.

Chapter 1 Applied Scene Chemistry

Table 1-1

5

General Hazardous Materials Behavior Model© Behavior Event

Stress

Breach

Release

Engulf

Impinge

Harm

Thermal

Disintegration

Detonation

Cloud

Short term

Thermal

Radiation

Runaway cracking

Violent rupture

Plume

Medium term

Radiation reactive

Attachments/openings

Rapid relief

Cone

Long term

Asphyxiation

Chemical

Punctures

Leak

Stream

Chemical

Mechanical

Splits or tears

Spill

Irregular deposit

Etiologic Mechanical

Event Interruption Principles Influences Applied Stresses

Influences Breach Size

Influences Quantity Released

Influences Size of Danger Zone

Influences Exposure Impinged

Influences Severity of Injury

Redirect impingement

Chill contents

Change container position

Initiate controlled ignition

Provide shielding

Rinse off contamination

Shield stressed system

Limit stress level

Minimize pressure differential

Erect dikes or dams

Begin evacuation

Increase distance from source

Move stresses system

Activate venting devices

Cap off breach

Dilute

Provide shielding

Ludwig Benner, Jr., 1978. Hazardous Materials Emergencies, Second Edition, Oakton, VA.

Technical Note The phase of matter of a substance is a reflection of the strength of the forces that exist between molecules of that substance. A substance that exists as a gas does so because the interactions that exist between molecules of that substance are negligible. If the interactions were stronger between molecules, that ­substance would be a liquid. Liquid substances have intermolecular forces that are strong enough to hold molecules together, but weak enough that molecules can still tumble over each other. Finally, solids exhibit very strong intermolecular forces.

In any environment, the surroundings of the event can be thought of as potential influencing forces on the container, and therefore on the product as well. Flame impingement is the environmental force or environmental factor that is influencing the container, which in turn has a direct impact on the product. It is this thought process that is the basis for the GEBMO. Within GEBMO there are six basic event categories, each having a set of event outcomes and each have an event interruption principle that the responder must address. In the flame impingement example, if the impingement has been short term, then shielding the tank may be a response option, and/or redirecting the thermal stress, or moving the tank. The interruption principles should be thought of as

actionable response from the actionable information that has been presented to the responders. Every event has clues or observable links toward the potential outcomes. It is up to the responder to identify these clues and use these observations toward scene stabilization. During the 1970s, while Ludwig Benner was at the N ­ ational Transportation and Safety Board, he created a new way of addressing a hazmat incident. He found that between 1969 and 1979, 268 fire fighters and police officers were killed and that their deaths were due in part to their training at the time (i.e., RPDM). Benner’s model, which describes the GEBMO, saw that traditional fire attack and extinguishment do not work for the hazardous materials incident. Additionally, he identified that, due to the complexity of the subject, many training experiences and events drove a cookbook approach to this type of incident or event and when applied, negative outcomes usually ensued. What Benner proposed was a ­sequence of events that will occur during the incident such that if one were to study these incident occurrences, one could predict the outcome.

Behavior Event: Stress Chemicals are everywhere. To use them, one must be able to transport them. This means that containers are the transport systems used for chemicals. It may be a 5-gallon bottle or a 4500-gallon (or larger) tanker. The container could be pressurized or non-pressurized, bulk or non-bulk, cryogenic or atmospheric temperatures. Even a pipeline should be viewed as a container. Whatever the container, once the product within the container

6

Hazardous Materials Chemistry, Third Edition

is disturbed, the container stressed, and its contents released, a stress event has occurred. A stress event is defined as a situation that causes a force or pressure that will cause the container to release its contents. This may be an external force that would change the shape of the container or an external force that would provide internal pressures the container was not designed to withstand. There are five stresses that can affect a container: 1. Thermal event: Describes an increase or a decrease of temperature. This can affect the container itself or the contents, causing the container to fail. 2. Mechanical event: Describes when a container has been dropped, overturned, or otherwise has collided with ­another object, causing a loss of container integrity. 3. Chemical event: Describes a reaction that is taking place within the container. This could be a problem with the transport of organic peroxides, which require an inhibitor. 4. Radiological event: Describes when radiation within or external to the container is such that it either heats the contents or causes failure of the container in such a manner that the material is released. 5. Etiological event: Describes an event in which bacteria or microbes slowly destroy the integrity of the container, thus releasing its contents, or the container itself becomes so fragile that any movement or disturbance can cause a rupture or failure of the container.

or tears). If the stress is not greater than the container’s ability to maintain its contents, then the stress or potential breach is averted for the time being. However, if the stress has caused the integrity of the container to fail or become so fragile that any movement or disturbing procedure can cause loss of container integrity, then a breach event occurs Figure 1-3 . The breach event can be a slow occurrence or as fast as a blink of an eye. The speed is dependent on the state of matter and the type of material involved. Types of breach events include: • Disintegration: Describes a catastrophic loss of the container’s integrity. • Runaway cracking: Describes development of a small tear or split in the outer shell of the container that can progress into a catastrophic event, depending on the state of matter. • Attachment openings: Describes the failure of the container’s apparatus (such as fusible plugs, relief valves, discharge valves). This may be due to a stress event or a mechanical event on the container. • Punctures: Describes holes to the container that are a mechanical stress, which have given the material within the container another route of exit. • Splits or tears: Describes holes to the container that have given the material within the container another route of exit.

Although radiological and etiological stresses are less common, potential of their occurrence still exists and must be considered. Upon arrival to the incident you may have one or more of these stressors applied to the container Figure 1-2 .

Figure 1-2  Upon arrival to the incident, you may have one or more of the five possible stressors applied to the container.

Figure 1-3  A breach event occurs when a stress causes the integrity of a container to fail or become so fragile that any movement or disturbing procedure results in the loss of the container’s integrity. © FIORENTINI MASSIMO/Shutterstock, Inc.

Behavior Event: Breach

Behavior Event: Release

Breach event is defined as a condition in which the material or energy is released through an opening (natural or man-made through covers, bung holes, or produced through stress-splits

Release event is defined as a condition when matter (solid, liquid, gas) and/or energy (energy may be produced by the chemical or the event itself or a combination) escapes the container.

Chapter 1 Applied Scene Chemistry

7

Figure 1-5  Dependent on the state of matter, the temperature, wind, and topography, a chemical can migrate and engulf an area.

Figure 1-4  The chemical family and state of matter can provide clues on the rate of the release event. © TFoxFoto/Shutterstock, Inc.

The container has had some level of stress placed on it, which in turn has caused it to open up through a breach, allowing the container’s material to be released and free to escape. The release event is dependent on the state of matter. Gases tend to release at higher rates than liquids or solids. Additionally, the chemical family can give you a clue on the rate of release Figure 1-4 . Types of release events include: • Detonation: Describes an explosive catastrophic event, which occurs over a millisecond, in which chemical or nuclear energy creates a shock wave that travels at supersonic speeds. • Violent rupture: Describes a catastrophic event, which occurs over a few milliseconds, in which chemical or nuclear energy creates a shock wave that travels at subsonic speeds (i.e., deflagration). • Rapid relief: Describes the material releases over time, depending on volume of the container and/or pressure and/or size of the opening within the container; may be a few seconds to minutes. • Spills or leaks: Describes release rates from minutes to hours; these are low pressure but can have enormous volumes.

that a material will follow once released from its container. Temperature differentials, wind, topography, materials state of matter, and chemical and physical properties all have a bearing on the behavior of the event Figure 1-5 . Types of engulfing events include: • Cloud or plume: Describes the gas event that can have somewhat predictable outcomes. • Cone: Describes any geometric shape that describes the pathway the dispersion could follow. • Stream: Describes the release of a material over an extended period of time that follows gravity and the contours of the land (topography). • Irregular deposits: Describe a very slow release, which may be unnoticed for extended periods of time.

Technical Note Cryogenic liquids, when catastrophically released, are thought to move into the environment fairly quickly. Interestingly enough, when cryogenic material is released into the environment through a breach of an opening, it builds in the general area until the temperature differential equalizes, then it moves out into the environment depending on the wind, humidity, and natural obstructions. At the epicenter of the release, water vapor becomes frozen, and as the differential becomes less, the frozen water vapor pops, causing additional “explosions” of vapor to occur.

Behavior Event: Engulfing Engulfing event is defined as a condition when a solid, liquid, or gas (energy such as radiation should be considered as well) is released forming a danger zone around the event. This is what the plume modeling, Emergency Response Guide (ERG) isolation distances, and As Low As Reasonably Allowable (ALARA) principles are suggesting. It is the identification of the pathway

Behavior Event: Impingement Impingement, or exposure to a chemical, describes the contact of the chemical with a container and/or people. It is the human exposure that you are primarily concerned about; however, a secondary impingement, which can cause your event to grow

8

Hazardous Materials Chemistry, Third Edition

• Mechanical: Describes damage and/or injury from high pressure release, such as fragmentation or movement of an object.

Figure 1-6  Impingement is dependent on the duration of the event, ­chemical characteristics, concentration of the material, and the state of ­matter to name a few. © Mike Meadows.

larger, is also a worry. From a human exposure standpoint, you should be concerned with the toxicology and the mechanisms that surround the toxic exposure Figure 1-6 . It is the event that causes the secondary injury (remember, the release event may be the cause of the primary injury due to pressure release, as an example). Impingement or exposure to a chemical can be described as: • Short term: What can occur over the next few minutes to several hours. • Medium term: What can occur over the next few days, weeks, and months. • Long term: What can occur over the next few years and possibly generations.

Figure 1-7  Understanding the harm that a chemical can present is the first step toward understanding the stabilization process of the incident. Courtesy of Rob Schnepp.

The Department of Transportation (DOT) placarding system can give clues to the type of harm a chemical can give Figure 1-8

Behavior Event: Harm Harm is the injury or damage that an engulfment may produce due to the nature of the hazardous substance’s state of matter Figure 1-7 . Without an appreciation of the factors that surround the incident’s potential harm, response personnel may encounter a negative impact from the event. Types of harm caused by hazardous materials include: • Thermal: Describes either hot or cold temperatures; this may be in the form of flame, radiant heat, or cryogenic liquids. • Radiation: Describes the damage from radiological energy and/or particles. • Asphyxiation: Describes the injury that can result from either simple (ones that displace oxygen) or chemical asphyxiants (ones that combine in the body to stop or inhibit respiration). • Chemical: Describes the injury resulting from contact to liquid/vapors from chemicals. • Etiologic: Describes injury that is caused by bacterial, viral, rickettsia, and/or biological toxins.

Figure 1-8  A placard for corrosives; both acids and bases are identified by this symbol. Bases are sometimes referred to as caustics or alkali. Courtesy of the U.S. Department of Transportation.

Technical Note TRACEM is a mnemonic to help remember the variety of harms that can be present at a hazardous materials event. It is the use of a system that identifies actionable information that one must address at the scene of an event. TRACEM can be thought of as a mechanism of injury. This mechanism is dependent on the state of matter and the chemical family. These are the harms that you are trying to predict when analyzing the incident, using detection equipment, and considering your mitigation options.

Chapter 1 Applied Scene Chemistry

All hazmat incidents have a beginning and an end that will self-correct if given enough time. You are trying to change the impact of these incidents, either from an immediate public safety standpoint or from a community viewpoint. It is the impact that you are trying to predict and mitigate by applying

a countermeasure to turn that impact in a positive direction. Every incident will follow a logical sequence of events, and it is up to the initial responder to recognize where in the process you are Figure 1-9 .

HAZARDOUS MATERIALS EMERGENCY MODEL Stage 1 NORMAL

Stage 2 STRESSING

Stage 3 REACTIVE

Stage 4 ESCALATE

Stage 5 UNSTABLE

ACTIVITY

NO OVER-

ADAPTS TO

STRESSES

STRESSES

OCCUR

Stage 6 OVERSTRESSING

Stage 7 INITIAL INJURY

NO INJURY

NO INJURY

OCCURS

OCCURS

Stage 8 Stage 9 SUBSIDING STABILIZED

STRESSING EVENT OCCURS

NORMAL

STRESS

ACTIVITY IN

INFLUENCES

PROGRESS

ACTIVITY

ACTIVITY

ACTIVITY

FAILS TO

BECOMES

ADAPT

UNSTABLE SUBSEQUENT

ELEMENT OF

SUCCESSIVE

ACTIVITY IS

ELEMENTS

STRESSES

EVENTS

OVER-

OVER-

ACCOMMO-

STABILIZE

STRESSED

STRESSED

DATED

ACTIVITY

FURTHER

BECOMES

INJURY

UNSTABLE

OCURS

EMERGENCY RESPONSE COUNTERMEASURES APPLIED TO INFLUENCE PROGRESSION OF EMERGENCY EVENTS Figure 1-9  The Hazardous Materials Emergency Model: All emergencies consist of a series of events that occur in a logical sequence. Ludwig Benner, Jr., 1978. Hazardous Materials Emergencies, Second Edition, Oakton, VA.

9

10

Hazardous Materials Chemistry, Third Edition

Problem Set 1-1 1. What are the six events in the GEBMO? 2. Which type(s) of breach behaviors give(s) the responder time to react, and what state of matter is the chemical in? 3. Asphyxiation is a result from what harm? 4. In the case study, which components of the model occurred?

Measurement At times you need to research chemical processes, read facility documents, and gather information about an incident. During times of intense pressure, you may only recognize things that you know and understand. It is for this reason you are reviewing some of the measurements that one may find in reference materials or facilities documentation.

Units of Measurement Units are a defined magnitude or scale that represent the result of the measurement Figure 1-10 . There are two common systems of measurements: the English system and the metric system. In the English system, pounds are used for weight, and gallons are used for volume. In the metric system, grams are used for weight, and liters are used for volume. A gallon of water in the English system is 3.79 liters in the metric system. Even though they are shown as different values with different units, they represent the exact same quantity of water. The metric system is preferred for most scientific work, and thus the numbers that are reported in the reference materials that are used by technicians are often in metric units.

Each measurement has its own unit. Example conversion factors follow: Length = Meter 1 yard = 0.9144 meter Volume = Meter cubed 1 gallon = 4546.09 cubic centimeter Mass = Kilogram 1 pound = 0.4535 kilograms Temperature = Kelvin 1 ºF = 255.93 ºK (−17.22 ºC) Mole = Amount of substance 1 kilogram of oxygen = 31.25 moles Pressure = Pascal 1 mm Hg = 6894.75 Pascal (0.0689 bars)

Technical Note In most reference books, computer programs, and reference ­materials, the country of origin determines the system of ­measurement that is being used within the documentation. It is handy to have a conversion chart to move the number into a unit that is familiar to you. Do not count on the Safety Data Sheet (SDS; formerly known as Material Safety Data Sheets, or MSDS), a reference book, or computer program to have these conversions for you.

In 1960, an international agreement on an international system was implemented. This convention comes from the metric system of measurement and is identified as SI (or le Systeme Internationale). In this system of measurement, the SI system uses prefixes to change the scale of the unit.

Technical Note Commonly used prefixes in the SI system Peta (P) Tera (T) Giga (G) Mega (M) Kilo (k) Hecto (h) Deka (da) Deci (d) Centa (c) Milli (m) Micro (µ) Nano (n) Pico (p)

Figure 1-10  The size of the container relates to the amount of the product in volume or weight. Courtesy of The DuPont Company.

1015 1,000,000,000,000,000 1012 1,000,000,000,000 109 1,000,000,000 106 1,000,000 103 1000 102 100 101 10 10−1 0.1 10−2 0.01 10−3 0.001 10−6 0.000001 10−9 0.000000001 10−12 0.000000000001

The SI unit for length is the meter, which is a little larger than the US yard (1 meter = 39.37 inches). The variations of the metric system are in powers of 10. Therefore, 1 meter is equivalent to 100 centimeters or 1000 millimeters. The prefix “milli” means 10−3, or that a mL is 1000 times smaller than a liter. Therefore, the appropriate conversion factor to use when converting between milliliters and liters is 1000 mL = 1 L Figure 1-11 .

Chapter 1 Applied Scene Chemistry

Converting metric units is very simple. All that is necessary is to change the position of the decimal point or add zeros. Kilo 1000 units

100 units

10 units

To convert to a smaller unit, move the decimal to the right.

11

which is also known as a liter. This liter can then be broken down into 1000 smaller units, which is called a milliliter or 1 cm3 or cc, and is used in medicine as a unit for drug administration.

Mass Mass is the fundamental measurement of the amount of matter, and the SI unit for mass is the kilogram. Fractions of this (smaller masses) are grams, milligrams, and micrograms:

Base unit

0.1 units Centi To convert to a 0.1 units Milli larger unit, move 0.001 the decimal to the left. units

1 kg = 1000 g 1 g = 1000 mg 1 g = 1,000,000 µg

Micro

Nano

Figure 1-11  The prefixes used in the metric system indicate the magnitude by which the unit is bigger or smaller than a base unit. © Jones & Bartlett Learning.

The appropriate conversion factors to use within the metric system are as follows (using the meter as the base unit): 1015 m = 1 Pm (petameter) 1012 m = 1 Tm (terameter) 109 m = 1 Gm (gigameter) 106 m = 1 Mm (megameter) 1000 m = 1 km (kilometer) 100 m = 1 hm (hectometer) 10 m = 1 dam (decameter) 10 dm = 1 m; (decimeter, dm) 100 cm = 1 m; (centimeter, cm) 1000 mm = 1 m; (millimeter, mm) 106 μm = 1 m; (micrometer, μm) 109 nm = 1 m; (nanometer, nm) 1012 pm = 1 m; (picometer, pm)

Application Tip

Temperature Temperature scales are used in chemistry to identify the flow of heat. Heat is required to change a material’s phase of matter or ignite material. Therefore, boiling points and ignition temperatures are often important to the first responder. The Celsius and Kelvin temperature scales are mostly used in the scientific community, while Fahrenheit is mostly used in the US outside of the scientific world. Although related, the responder must recognize the scale and adjust appropriately so that he or she understands the temperature reference Figure 1-12 . The Celsius scale is based on the freezing and boiling point of water, with the freezing point defined as 0°C, and the boiling point defined as 100°C. Kelvin uses the same-sized units as the Celsius scale, but there is an absolute zero in the Kelvin scale. At this temperature, 0°K, theoretically, all molecular movement stops (−273.15°C). The temperature conversions are as follows: °F = 1.8°C + 32 °C = (°F – 32)/1.8 K = 273.15 + °C There is also an absolute temperature scale associated with the Fahrenheit scale. It is called the Rankin scale. In the Rankin scale, like the Kelvin scale, the lowest possible temperature is zero. However, the size of the degree in the Rankin scale is the same as the size of the degree in the Fahrenheit. The size of the Celsius degree is 1.8 times bigger than the Fahrenheit degree. (Note equation above.)

Pressure An example of a metric application would be a response for an inhalation injury that requires a hydrofluoric acid mixture of 6 milliliters (cc) sterile water into 3 milliliters (cc) of a 10 percent calcium gluconate solution. This 9 cc of diluted drug would then be administered via a nebulizer (updraft) with oxygen.

Volume Volume is the amount of space a material occupies and includes three length measurements; height, width and depth. Imagine a box one meter wide, one meter high and one meter deep. The volume of that box is a cubic meter or a kilo liter. If this is divided into a thousand smaller units, you have a decimeter (dm3),

Pressure is defined as the force exerted on the sides of the container divided by the area of the container, and is often measured and reported in millimeters of mercury (mm Hg). Just like temperature, volume, and length, pressure also has a variety of measurement units. You may be most familiar with mm Hg; however, the Pascal is the SI unit.

Technical Note In medicine, the torr is used to describe pressures within blood gases and lung pressures. 1 torr = 1 mm Hg.

12

Hazardous Materials Chemistry, Third Edition

Temperature Scales

100°C

212°F

373.15°K

Boiling point of water

0°C

32°F

273.15°K

Freezing point of water

-18°C

0°F

255°K

-273°C

-460°F

0°K

°Celsius

°Fahrenheit

Absolute Zero

°Kelvin

Figure 1-12  Comparing Fahrenheit, Celsius, and Kelvin temperature scales, referencing boiling points, freezing points, and absolute zero. In the laboratory, temperatures are normally measured in Celsius, while formulas for some calculations require temperatures be in Kelvin. © Jones & Bartlett Learning.

The definition of a Pascal is the force in Newtons divided by the area in square meters (1 Pa = 1 Newton/m2). Each Pascal is a very small unit of measurement, so pressures are frequently described as kilo Pascals (kPa). Another unit of measurement originating in London around 1900 as the formal unit of m ­ easure, for meteorological pressure, the bar or millibar, is still used today in reporting the weather. 1 atmosphere (ATM) = 760 mm Hg = 101.325 kPa = 1.013 bar

Avogadro’s Number The unit of measurement under the SI system for an amount of a substance is the mole. A mole is simply a counting unit that means a certain number of items used by chemists. Because atoms are so small, a large number of them are necessary to obtain masses that can be measured. The mole to a chemist, is not unlike the dozen to a baker. Instead of counting donuts by ones, a baker will instead count donuts by 12s. Analogously, instead of counting atoms (or molecules) by ones, a chemist will count them by moles, which means 6.02214 × 1023 items. The origin of this number comes from the fact that there are 6.02214 × 1023 atoms in 12 grams of carbon 12. This number is called Avogadro’s number: 1 mole = 6.02214 × 1023

You can think of the mole as being used in the same way as the other counting units you are familiar with. For example: 1 couple = 2 items 1 dozen = 12 items 1 score = 20 items 1 ream = 500 items 1 mole = 6.02214 × 1023 items Consequently, the molar masses found on the periodic table all correspond to the mass, in grams, of 6.02214 × 1023 atoms of that particular element. Because a mole means the same thing regardless of the material, a mole of different types of materials will have different masses and volumes Figure 1-13 .

Standard Temperature and Pressure Standard temperature and pressure is defined as 0°C (32°F) with a pressure of 760 mm Hg (14.7 psi or 760 mm Hg or 101.325 kPa or 1 ATM). 1 mole of an ideal gas at STP occupies 22.41 liters (see Chapter 6, Gases).

Energy The last units of measurement to discuss are units that describe energy. The joule is the SI unit for energy. In the laboratory, only changes in energy between two states can be measured and is

Chapter 1 Applied Scene Chemistry

13

appropriate conversion factor. The appropriate conversion factor is 1.61 km/1 mi, because it is the one for which the given units will cancel and the desired value will remain in the numerator. 1.5 mi ×

Content removed due to copyright restrictions

1.61 km = 2.4 km 1 mi

In every dimensional analysis problem, once you have set up the appropriate conversion factor, you will simply complete the math by multiplying the values in the numerators and dividing by any values in the denominator.

Problem Set 1-2

Figure 1-13  A mole means the same thing regardless of the material.

defined as the sum of heat and work. Just like the SI unit for pressure, because the joule is very small, the kilojoule (1000 joules) is normally used to describe energy: 1 calorie = 4.184 joules (J)

Converting Between Units Different types of physical measurements and different types of units in which measurements can be expressed will be discussed Table 1-2 . For example, the length of a road can be measured in miles or in kilometers, and 1 mile is equal to 1.61 kilometers. Because 1 mile = 1.61 kilometers, you can use the ratio of those two numbers as a conversion factor. A conversion factor is a ratio in which the numerator and the denominator are equal to each other but are expressed in different units. Therefore, multiplying a measurement by a conversion factor will not change the amount of the measurement, but will change its units. Because the numerator and denominator are equal, multiplying by a conversion factor is like multiplying a measurement by 1 and will not change the actual quantity, but allows it to be expressed in a different unit. If 1 mile = 1.61 kilometers, the ratio 1.61 km/1 mi is a conversion factor, and the ratio 1 mi/1.61 km is also a conversion factor. To use a conversion factor to convert between units, use the form of the ratio that will cause your given units to cancel and the desired unit to remain in the numerator. This process of converting between units is called dimensional analysis. Given  Unit ×

Desired  Unit = Desired  Unit Given  Unit

For example, if you wished to express the length of a road in kilometers when you know that its length is 1.5 miles, you would simply multiply the measurement 1.5 miles by the

1. During your research of a product while at the scene of a hazmat incident, you find that the vapor pressure is noted in the reference data as 1.283 bar. What is the vapor pressure in mm Hg, psi, kPa, ATM? 2. How many gallons are there in one cubic meter? 3. What is the difference between tera and mega?

Scientific Notation Several kinds of numerical measurements can be found in the literature. Scientific notation is used to express very small and very large numbers, and is a product of two numerical expressions, where the first term is the digital identifier and the second term is the exponential. This method of numerical expression is widely used in scientific documentation, facility paperwork, and transport documents. Take, for example, the number 5280 is the number of feet in a mile. 5280 feet = 1 mile or 5.280 × 103 feet = 1 mile In other words, you have taken 5.280 and multiplied it by 10 three times. 5280 feet = 5.280 × 101 × 101 × 101 = 5.280 × 103 feet So, if a number is less than 1, say the weight of a quarter (about 80 quarters make 2 rolls, which is 20 dollars, and makes about a pound) is 1/80 of a pound, then it is 0.0125 or in scientific notation: 1.25 × 10−2 From these two examples, you can see that when numbers are greater than one (whole numbers), the shift is to the left and the exponent is positive: 5280 = 5.280 × 103 When there is a number that is less than one (fractions), the shift is to the right and the exponent is negative: 0.0125 = 1.25 × 10−2

Table 1-2

Conversion Table of Common Volumes, Lengths, and Weights Length Measurements Statute Miles

Meters

Yards

Feet

Inches

Statute Mile

1

1609.5

1760

5280

63,360

Kilometer

0.6214

1000

1094

3280.8

39,372

Nautical Mile

1.1516

1853

2027

6080.2

72,960

Centimeters

Meter

1

1.094

3.2281

39.57

Yard

0.9144

1

3

36

91.44

Foot

0.3048

0.3333

1

12

30.84

Inch

0.0254

0.0277

0.08333

1

2.54

0.0328

0.3937

1

Centimeter

182.9

Area Measurements Square Miles

Acres

Square Meters

Square Yards

Square Mile

1

640

2,589,998

3,097,600

Square Kilometer

0.3861

247.1

1,000,000

1,195,985

Acre

0.00156

1

Square Yard

4046.9

0.00021

Square Foot

Square Feet

4840

43,560

0.8361

1

9

0.0929

0.1111

1

Volume Measurements Cubic Inches Cubic Inch

1

Cubic Foot

1728

Cubic Feet

Cubic Yards

0.00058 1

0.037

Cubic Yard

27

1

Cubic Meter

35.314

1.3079

Liquid Volume Cubic Inches

Liters

U.S. Pints

U.S. Quarts

U.S. Gallons

U.K. Pints

U.K. Quarts

U.K. Gallons

Liter

61.025

1

2.1134

1.0567

0.2642

1.76

0.88

0.22

U.S. Pint

28.875

0.473

1

0.5

0.125

0.8327

0.4164

0.1042

57.75

0.9643

2

1

0.25

1.665

0.8327

0.208

3.785

8

4

1

6.66

3.33

0.8327

34.668

0.5688

1.201

0.6

0.15

1

0.5

0.125

69.335

1.1365

2.402

1.201

0.3

2

1

0.25

4.546

9.616

4.808

1.201

8

4

1

U.S. Quart U.S. Gallon U.K. Pint U.K. Quart U.K. Gallon

231

277.34

Dry Measure U.S. Pints

U.S. Quarts

U.S. Bushels

U.K. Pints

U.K. Quarts

U.K. Bushels

Liter

Cubic Inches 61.025

Liters 1

1.8162

0.908

0.0284

1.759

0.8795

0.0275

U.S. Pint

33.6

0.55

1

0.5

0.156

0.969

0.4845

0.015

U.S. Quart

67.2

1.101

2

1

0.0313

1.938

0.969

0.03

U.S. Bushel

2150.42

35.238

64

32

31.01

0.969

U.S. Pint

34.68

0.5679

1.032

0.516

0.0164

1

0.5

0.0156

U.K. Quart

69.35

1.1359

2.064

1.032

0.0323

2

1

0.0313

66.052

33.052

1.032

64

32

U.K. Bushel

2219.34

36.367

1

62.016

1

Mass Grams Gram Kilogram Ounce Pound Metric Ton Short Ton Long Ton

1 1000 28.349 435.59

Kilograms

Ounces

0.001

0.0353

1

35.274

0.0284

1

0.4536

16

1000 907.2 1016

Pounds

Metric Tons

Short Tons

Long Tons

0.0022 2.2046 0.0625 1 2204.6

1

1.1023

0.9842

2000

0.9072

1

0.8929

2240

1.016

1.12

1

Chapter 1 Applied Scene Chemistry

Application Tip On occasion, you may want to visualize measurements. For example, toxic values that will be discussed later have small numbers, or in this case, negative exponents to identify the degree of toxicity. As a visual, one part per million is one gram per a million grams, which is similar to one milligram in one liter of water, which is one part per million. Therefore the size of one part per billion (ppb) is smaller than one part per million (ppm), and one part per trillion (ppt) is yet smaller than one part per billion. Looking at the detection equipment, there are instruments that can register 1 ppm, 1 ppb, and 1 ppt.

Significant Figures Now the question becomes, how precise do these numbers need to be? Or, how precise is that piece of information that you are referencing? This is where significant figures are important. These are the number of digits in a measurement that were recorded using a measuring tool. That tool could be a scale for weights, a ruler for length, or a graduated cylinder for volume; in all cases, the numbers that are reported are consistent with the level of precision of the instrument used when making the measurement. The numbers used when reporting actual measurements are called significant figures. In all measurements, the last digit reported if the measurement is uncertain. Sometimes you will see notations after the number such as ±1, which identifies that the last digit is uncertain and that the level of uncertainty is plus or minus 1. Sometimes it is necessary to perform calculations using measured values. When doing so, it is important that the calculated value reported is not written in a way that is more precise than the original measurements that were used to calculate that value. For this reason, there are rules for counting significant figures in measurements and rules for how many significant figures to include in the answer of a calculation performed with measured values. The rules for counting significant figures in measurements are as follows: • All nonzero digits are significant. • Zeros between two digits are significant. Looking at the boiling point of fuel oil, which is 304, the zero is a significant figure. • Zeros to the right of a digit (non-zero number) and right of the decimal place are significant. The specific gravity of 50 percent sulfuric acid is 1.40, where the zero at the end of 1.4 is significant. • Zeros that occur after the decimal but before the first nonzero number are NOT significant. The vapor pressure of

15

malathion is 5 × 10−6 or 0.00005, and here, the zeros are NOT significant figures. • Zeros at the end of a number that do not contain a decimal are ambiguous, but usually not considered significant. Take the volume of potential gas found in a LPG tank, similar to the one in the case study. These tank cars can hold between 4000 and 45,000 gallons of product. In each case, the zeros in each number are usually not significant. The rules for how many significant figures to include in the answers of calculations using measured values are as follows: • For addition and subtraction, the calculated value should have the same number of decimal places as the measurement with the least number of decimal places. • For multiplication and division, the calculated value should have the same number of significant figures as the measurement with the fewest number of significant figures. For example, if a chemist were to measure the density of a material, two measurements would need to be made: a mass measurement and a volume measurement. Imagine the density of one of the cylinders in Figure 1-14 were to be measured such that the identity of the metal could be determined. The chemist may measure the cylinder’s mass on a digital balance that reads to three decimal places Figure 1-15 . If the sample had a mass of 92.280 g, that measurement would have five significant figures in it.

Figure 1-14  To determine the type of metal used in each cylinder, a chemist would measure the density of each cylinder. © Phonlamai Photo/Shutterstock, Inc.

The volume of your sample cylinder may be measured with a graduated cylinder Figure 1-16 . Note that every milliliter is marked on the cylinder. A chemist would measure density of a solid material by filling the cylinder with some known volume of water, placing the sample in the graduated cylinder

16

Hazardous Materials Chemistry, Third Edition

In your experiment, imagine that the level of water before the sample was introduced was 50.0 mL and the level of water after the sample was introduced was 60.3 mL. In this instance, you would calculate the volume of the cylinder to be 10.3 mL. Now that both the mass and the volume have been measured, you can calculate the density of the cylinder. To report the density using the correct number of significant figures based on the measurement systems employed, you need to consider the rules of significant figures when using measured values in calculations. When calculating the density, you will use two measured values: a mass of 92.280 g, which contains five significant figures, and a volume of 10.3 mL, which contains three significant figures. (Note that the addition/subtraction significant figures rule was used to calculate the volume and kept one decimal place.) Because mass is divided by volume to calculate density, apply the multiplication and division rule and report a density with three significant figures. D = 92.280 g/10.3 mL Figure 1-15  A type of digital balance that reads to three decimal places. ©Kwanchai.c/Shutterstock.

containing the water, and measuring the volume of the water with the sample. The difference between the water volume and the volume of the water with the sample would give the volume of just the sample. Because each milliliter is marked and the last digit in any measurement represents the one uncertain digit, the volume determined using the graduated cylinder pictured would contain one decimal place. The chemist would estimate the tenth place by looking at where the water level lands between two graduation marks.

A calculation display would show the following number 8.959223301. However, based on the precision of the measurements that went into that calculation, it would be inappropriate to report that many digits. The reported density therefore should only contain three significant figures. In this example, you would report that the calculated density is equal to 8.96 g/mL. Error in measurement should not be confused with a mistake and is actually a variation within the measurement system being used. Error is the tolerance that the measurement may represent. It is that margin of error that is accepted within the industry, process, or event. This is where you will see numbers, such as ±1, identifying that the tolerance is plus or minus 1 Figure 1-17 .

Figure 1-16  A graduated cylinder is used to measure volume.

Figure 1-17  Differences in measurement precision.

Courtesy of Michael Montigny.

Courtesy of Michael Montigny.

Chapter 1 Applied Scene Chemistry

Tolerance is the range of potential variation that is allowed. For example, older oxygen sensors had a 0.1 percent drift, which is acceptable, and thus equals the tolerance of your instrument. A movement of 0.2 percent is not acceptable, and therefore one must look for potential reasons for this deprecation of oxygen. Problem Set 1-3 1. Your measurement of 254.0 meters has how many significant figures? a. 2 b. 4 c. 3 d. 1 2. The pressure that you calculated in mm Hg is 0.00718. How many significant figures do you have? a. 2 b. 4 c. 3 d. 1 3. The pressure 0.00718 mm Hg written in scientific notation is: a. 7.18 × 103 mm Hg. b. 7.18 × 10−3 mm Hg. c. 7.18 × 10−2 mm Hg. d. 7.18 × 105 mm Hg.

Technical Note The precision of a measurement tool is determined by the smallest unit to which it can measure.

Scientific Method and Decision Making Scientific Method Each time you respond to a hazardous materials or weapons of mass destruction (WMD) event, you use principles of the scientific method. This method was developed to organize your thoughts. It is an order of steps from which logical deductions can be made. The scientific method is a process of four steps, and each step has a very specific purpose: • Step 1. The purpose, question, or research. What do you want to learn, and why are you looking at this problem? Look for all information that is known. • Step 2. Hypothesis. This is a prediction of what you think may happen. • Step 3. Experimentation and analysis. This is the test of the hypothesis. Record what does occur during the experimentation. • Step 4. Conclusion. In this phase, look at the data, and ask whether or not the data supports the hypothesis. If the data does not support the hypothesis, determine

17

what additional experimentation can be done to either further disprove your hypothesis or come up with a more plausible hypothesis.

Application Tip Benner’s model is a good example of the use of the scientific method for understanding the phenomena that occur in the natural world. The scientific method begins with observation. Ludwig Benner observed hazardous materials events and began to recognize specific patterns in what he observed. Making observations is one form of collecting data. After believing that one has noticed a trend, a scientist will formulate a hypothesis. A hypothesis is a testable statement that attempts to explain the phenomenon observed. This hypothesis is used to predict the outcome of an experiment. Depending on the results of the experiment, the hypothesis is either supported or not. When the experiment does not support the hypothesis, the process of observation, hypothesizing, and experimenting is repeated.

When you arrive on a scene, certain issues should be prioritized based on urgency. The immediate issues such as denying entry, eliminating ignition sources, and formulating an evacuation plan should be addressed first. Issues that will require information, such as air monitoring and/or reconnaissance missions, should be addressed second. Last are those issues that can wait until the first two have been appropriately handled. The unfortunate part is that emergency incidents do not necessarily follow your time table, but rather follow the time table of the laws of physics and chemistry, which may be very quick or slow (remember the discussion on the GEMBO). When you arrive on a scene, you can use the scientific method to start the decision-making process (see Chapter 12, Risk-Based Response).

ALERT Remember, the lack of detection does not prove the lack of a hazard.

Decision Making You can look at the six events in the GEMBO model and combine a few to come up with four basic steps, each having a very specific list of action items. You will learn that it is the chemistry that will help with this analysis. By understanding the basic principles and harms of each chemical family, you can then apply this toward this analysis process. • Step 1: Scene dynamics observed. Once on scene, a size-up of the incident is what first responders have

Hazardous Materials Chemistry, Third Edition

• Step 3: Develop a hypothesis—an educated guess. This is based upon all the data that you have gathered through air monitoring, occupancy/location, container shape and size, placards and labels, and facility papers and documents. It is through the detection methodology that you confirm or deny the possible chemical families. ▪▪ Detection strategy to identify the potential possibilities ▪▪ Data, information, and observations collected from the detection strategy to confirm or deny families • Step 4: Conclusion—develop a response plan. Once a list of potential families or general hazards has been identified, a controllable action plan can be implemented. It is through this process that you can revise this action plan (commonly called the Incident Action Plan), and it should be revisited several times during an incident. Review this chapter’s case study. How many times would you evaluate this incident? Simplified versions of the scientific method, such as the APIE (analyze, plan, implement, evaluate) or OODA (observe, orient, decide, act) charts, can be used to help prioritize how you approach and address specific issues encountered in any hazmat situation Figure 1-18 .

E RV

AT U AL

E DE

T

PL

EN

EM

AN

DE

CI

PL

A

SE

YZ

AL

T AC

OB

AN

E

Analyze an incident Plan the response Implement the plan Evaluate the progress

IM

been trained to do. In a fire situation, a quick 360 of the structure, or at least observing three sides of the building, provides the responder with an idea of fire progression. At the scene of an emergency medical services (EMS) call, the responder looks for mechanism of injury and scene clues, such as empty pill bottles. At the hazmat call, the responder looks at the basic hazmat clues, such as occupancy location, container shape and size, placards and labels, facility documents, and/or shipping papers. Each of these basic clues gives the responder the potential substances that are potentially present. This chapter’s case study identified that a train derailed with potential damage to a tanker that contained a liquefied petroleum gas. This was a clue. Some types of chemical observations are fumes, smoke, liquids, and/or solids. Looking at the GHMBO; can you identify the stress, breach, and/or release, thus providing the information on engulfment, impingement, and the harm? • Step 2: Gather initial critical readings through a strategic monitoring plan. You have to have a plan during the monitoring mission. Part of that monitoring mission is to have an idea of what you are monitoring for. In other words, if you get a depression of oxygen in a building, then there is a gas being released into that building. If, in association with the low oxygen readings, you have a lower explosive limit (LEL), then there is a definite flammable gas environment. Looking at the chemical families, you can see that there are a small group of chemicals that fall into this category. Detection strategy includes: ▪▪ Check for radiation. ▪▪ Check for acids, bases, oxidizers, peroxides, and explosives. ▪▪ Check for flammables/combustibles. ▪▪ Check for oxygen concentrations. ▪▪ Check for toxic qualities. Utilize multiple technologies when discovering potential hazardous substances. This is when understanding chemical families becomes valuable. Knowing what chemical families will register on certain instruments allows the responder to look at the incident from different air-monitoring angles. For example, if the scene has indications of acids, knowing if there are organic acids versus inorganic acids is a health-and-safety issue. Research the chemical families that seem logical to you, either through your understanding of occupancy and location, or the chemical families that show certain monitoring results. Gathering the clues and/or information suggests potential families that you can now confirm or deny their presence.

EV

18

T

EN

I OR

B

Figure 1-18  Examples of A. APIE and B. OODA charts. © Jones & Bartlett Learning.

Problem Set 1-4 1. What are the steps in the scientific method? 2. Which step identifies the use of basic hazmat clues such as air monitoring and placard recognition? 3. Which step addresses radiation? 4. What is the step that identifies three immediate hazard areas and what are they?

Case Study Answers 1. What has happened? According to the facts provided, a major derailment has occurred, which has two known chemical cars in the accident. These cars, as stated, contain LPG. Part of the evaluation process is to reference basic facts. In this case study, there are two train cars that can have pressures of 100–600 psi and capacities of 40,000–45,000 gallons. With propane having an expansion ratio of 270:1, even if on the low side of 40,000 gallons, you have roughly over 10 million gallons of vapor potential (270 × 40,000 gallons = 10,800,000 gallons). You also know that in derailments, gouges, slits, and tears are a big issue. In this, as many cases, the rail burn occurred against a weld seam because it was a weakened point. In addition, the movement tactics may have caused further damage. Looking at the GHMBO model you can forecast this event.

2. What will or could happen? You see that the temperature at the time of the accident is in the 20ºF, range and perhaps as low as the mid-teens. The temperature is not changing much from the time of the accident until February 24, when the temperature rose to the mid-50s. Looking at the boiling point of liquefied petroleum gas (LPG or propane), you

see that it has a boiling point of −43.6°F. At mid-teens or 20s, the gas activity had been reduced; however, at 50°F with solar load, you now have a brand new problem. Additionally, where does LPG go? What is its vapor (specific) density? Where was the monitoring system used? Did the operator take into account that it takes time for the gas to enter the instrument? Or was the environment such that the operator was at the upper explosive limit (UEL) all along and did not recognize what scale was being read? You can second-guess all day long, but the facts remain: This was a hazardous flammable environment and controls should have been in place. Through your use of the GEBMO, you can see how this emergency will finish.

3. What can you change? At a known flammable gas release, you can look at the GEBMO and see the event unfolding. Controlling ignition sources, evacuation, and managing the cars with care are the top priorities in all flammable gas events. Many times, heavy equipment must be brought into the area, as in this event. You know that by doing this, you have created an ignition source. You must know how to manage this ignition source while at the same time managing the flammable gas.

Design Credits: RedFlames: Drx/Dreamstime.com; Steel texture: © Sharpshot/Dreamstime.com; Orange flames: © Jag_cz/Shutterstock, Inc.; Stacked photo background: © Vitaly Korovin/Shutterstock, Inc.; Paper: © silver-john/Shutterstock, Inc.; Application Tip: © iraua/Shutterstock, Inc.; Alert: © iraua/Shutterstock, Inc.; Technical Note: © Eky Studio/Shutterstock, Inc.

WRAP-UP In Summary • Understanding the basic concepts that chemical and physical properties bring forward can aid the responder in predicting outcomes. Associating this with models such as Benner’s model and the characterization model, a responder can look at hazardous materials/WMD events in their totality. • These methods of quick evaluation assist the emergency responder to evaluate using a systematic process. The use of the scientific method at a hazmat/WMD event can be incorporated into emergency response by looking at three characterization areas. • These three characterization areas are scene, hazard, and exposure, with each having components that can highlight that characterization within the larger emergency scene. • By evaluating one of these characterizations, you inherently start evaluating the second and possibly a third. With one characterization complete, analysis starts; with two characterizations complete, outcomes can be predicted; with three characterizations complete, the entire scene is identified with all hazards risks and benefits. • Inserting this information into the APIE process, which is a simplified version of the scientific method, one can see how a reevaluation of the process can lead to prediction, complete analysis, and positive scene outcome.

• As with anything in science, accurate measurements and understanding of the numbers can indicate how dangerous a specific incident may become. Numbers that are acquired during a hazmat/WMD incident should mean something to the emergency responder. Too often, emergency responders just look for the number blindly placed on a tactical worksheet. • These are measurements of a chemical and how it is going to react within an environment. In understanding what these measurements are telling you in relationship to the scene and the instrumentation you are using, you will have clues to the potential chemical families that you encounter. • Chemistry can be a complicated subject if you allow it to be. Learning how to break down each component of analysis and arrive at logical conclusions, in addition to the process of looking at chemicals in the broad view to identify specific hazards within families, will provide you the prediction powers suggested by Benner’s model. • It is your ability to look at risk, evaluate these risks, minimize the hazard, and identify the problem such that you can mitigate the incident and reduce potential victim/ community exposure.

Key Terms asphyxiation  Injury resulting from either simple (ones that displace oxygen) or chemical asphyxiants (ones that combine in the body to stop or inhibit respiration). attachment openings  The failure of the container’s apparatus (such as fusible plugs, relief valves, discharge valves). This may be due to a stress event or a mechanical event. breach event  A condition in which the material or energy is released through an opening (natural or man-made through covers, bung holes, or produced through stresssplits or tears). Celsius  A temperature scale defined by setting the freezing point of water to zero and the boiling point to 100°C; also known as Centigrade. chemical  Injury resulting from contact to liquid or vapors from chemicals. chemical event  A reaction that is taking place within the container. Such is the problem with transport of the organic peroxides that require an inhibitor during transport. cloud  The gas event that can have somewhat predictable outcomes; also known as a plume. cone  Any geometric shape that describes the pathway the dispersion could follow.

detonation  An explosive catastrophic event, which occurs over a millisecond, in which chemical or nuclear energy creates a shock wave that travels at supersonic speeds. dimensional analysis  The process of converting between units. disintegration  A catastrophic loss of the container’s integrity. engulfing event  A condition in which a solid, liquid, or gas (energy such as radiation should be considered as well) is released forming a danger zone around the event. error in measurement  A variation within the measurement system being used. Error is the tolerance that the measurement may represent. etiologic  Injury caused by bacterial, viral, rickettsia, and/ or biological toxins. etiological event  An event in which bacteria or microbes slowly destroy the integrity of the container, thus releasing its contents, or the container becomes so fragile that movement or disturbing procedures can cause a rupture/ failure of the container. Fahrenheit  Scale of temperature where the freezing point is 32°F and boiling point is 212°F using the standard of water.

Chapter 1 Applied Scene Chemistry

GEneral hazardous materials Behavior MOdel (GEBMO)  A system by which one can look at the event in its entirety, establishing potential outcome; developed by Ludwig Benner. impingement  The contact of the chemical with a container, and/or people; also known as exposure to a chemical. irregular deposits  A very slow release, which may be unnoticed for extended periods of time. Kelvin  The absolute temperature at which all thermal motion on the molecular level theoretically stops at zero. long term  What can occur over the next few years and possibly generations. mass  Quantity of matter within a substance; 1 pound = 0.4535 kilograms. mechanical  Damage and/or injury from high pressure release, fragmentation, overpressure during an explosion, and movement of an object, to name a few. mechanical event  When a container has been dropped, overturned, or otherwise has collided with another object, causing a loss of container integrity. medium term  What can occur over the next few days, weeks, and months. meter  Fundamental unit of length used in the metric system (1 yard = 0.9144 meters). mole  A unit of measurement defined to be 6.02214 × 1023 items (atoms, molecules, particles, etc.). Pascal  The unit of measurement for pressure that is equal to one Newton/square meter; 1 mm Hg = 6894.75 Pascals. punctures  Describes holes in the container that are a mechanical stress, which have given the material within the container another route of exit. radiation  The damage from radiological energy and/or particles. radiological event  When the radiation within or external to the container is such that it either heats the contents, or causes failure of the container in such a manner that the material is released. rapid relief  Describes the material releases over time depending on the volume, pressure, and/or size of the opening within the container; may be a few seconds to minutes. recognition primed decision-making process (RPDM)   A concept that identifies what you think by matching previous events to the currently presented problem. release event  A condition when matter (solid, liquid, gas) and/or energy (energy may be produced by the chemical or the event itself or a combination) escapes the container. risk-based response (RBR)  Systematic process by which responders analyze a problem involving hazardous materials or weapons of mass destruction through the evaluation

of product, container, and environmental influences to understand the potential consequences and determine the appropriate actions. runaway cracking  When the outer shell of the container develops a small tear or split that can progress into a catastrophic event, depending on the state of matter. scientific method  A process of discovery utilizing observations and grading each observation with potential possibilities. Each possibility is then evaluated and either ruled in or out of the conclusion. scientific notation  A method to display either very large or very small numbers within a meaningful context using powers of 10. short term  What can occur over the next few minutes to several hours. SI  In 1960, an international agreement on an international system was implemented. This convention comes from the metric system of measurement and is identified as SI (or le Systeme Internationale). spills  Release rates from minutes to hours, these are low pressure but can have enormous volumes; also known as leaks. splits  Holes to the container that have given the material within the container another route of exit; also known as tears. stream  The release of a material that is over an extended period of time that follows gravity and the contours of the land (topography). stress event  A situation that causes a force or pressure that will make the container release its contents. This may be an external force that would change the shape of the container and/or that would provide internal pressures the container was not designed for. thermal  Either hot or cold temperatures; may be in the form of flame, radiant heat, or cryogenic liquids. thermal event  An increase or decrease of temperature. This can affect the container itself or the contents, causing the container to fail. tolerance  The range of potential variation that is allowed. TRACEM  Thermal, radiation, asphyxiation, chemical, etiological, and mechanical is a mnemonic in order to remember the variety of harm that can be present at a hazardous materials event. violent rupture  A catastrophic event, which occurs over a few milliseconds, in which chemical or nuclear energy creates a shock wave that travels at subsonic speeds (i.e., deflagration). volume  The amount of space an object occupies, or the three-dimensional quantity or capacity of a container (1 gallon = 4546.09 cubic centimeters).

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WRAP-UP Review Questions 1. What is the stage which detonation occurs? a. Impinge b. Breach c. Stress d. Release 2. Which of the following possibly occurred at the Waverly Tennessee incident as described in the case study? a. Violent rupture b. Runaway cracking c. Plume dispersion d. Chemical impingement 3. How are impingements described in the GEBMO? a. Due to dispersion patterns b. The temperate of the product c. Duration of time d. Container shape and size 4. Which type of stress is possible but least likely at a hazardous materials event? a. Radiation, mechanical b. Etiological, radiation c. Chemical, mechanical d. Etiological, chemical 5. What does SI mean and why is it important? 6. What is SI unit of measurement for temperature? 7. How many milligrams in a one-gram weight? 8. If the Fahrenheit temperature is 68°F, what is the corresponding Celsius measurement? 9. What are the terms used to describe how close measurement sets are to one another and the true or accepted value?

10. The vapor pressure of liquid parathion is 0.00005. How many significant figures does it have? 11. The vapor pressure of MEK is reported as 80.21 mm Hg. How many significant figures are there? 12. Oxygen sensors have drift (which is now compensated for by the instrument). What is this drift called? 13. How many significant digits are in the following measurements? a. 2.039 cm b. 130.0 lb c. 0.34 g d. 101 inches e. 60.02 seconds 14. What is the area of a room that is 26.0 ft. by 128.5 ft.? Report the area with the correct number of significant digits. 15. The volume of a liquid sample was measured to be 33.0 cm3. The mass was determined to be 102.402 g. What is the density of the sample? Report your answer using the appropriate number of significant figures. 16. The mass of an empty beaker was determined to be 70.239 g. A solid sample was placed in the crucible and the mass of the beaker and sample together was determined to 100.43 g. What is the mass of only the sample in the beaker? Report this mass using the correct number of significant figures. 17. Which step highlights the use of detection strategies ? a. Step 1 b. Step 2 c. Step 3 d. Step 4

Problem Set Answers Problem Set 1-1 1. What are the six events in the GEBMO? Stress, breach, release, engulf, impinge, harm 2. Which type(s) of breach behaviors give(s) the responder time to react, and what state of matter is the chemical in? Spills and leaks; liquid 3. Asphyxiation is a result from what harm? Exposure to simple and chemical asphyxiants

4. In the case study, which components of the model occurred? Temperature dependent, stress, breach, release, engulf and impinge, which gave the result of thermal, asphyxiation, chemical, and mechanical harm. Problem Set 1-2 1. During your research of a product while at the scene of a hazmat incident, you find that the vapor pressure is noted in the reference data as 1.283 bar. What is the vapor pressure in mm Hg, psi, kPa, and ATM?

Chapter 1 Applied Scene Chemistry

1.283 bar × 750.063 mm Hg = 962.33 mm Hg 1.283 bar × 14.503 psi = 18.607 psi 1.283 bar × 100 kPa = 128.3 kPa 1.283 bar × 0.9869 ATM = 1.266 ATM 2. How many gallons are there in one cubic meter? 1 cubic meter = 264.17 gallons 3. What is the difference between tera and a mega? Six zeros; tera is a million times larger than mega Problem Set 1-3 1. Your measurement of 254 meters has how many significant figures? c. 3 2. The pressure that you calculated in mm Hg is 0.00718. How many significant figures do you have? c. 3 3. The pressure 0.00718 mm Hg written in scientific notation is: b. 7.18 × 1023 mm Hg

Problem Set 1-4 1. What are the steps in the scientific method as they relate to a hazmat event? • Step 1: Scene dynamics observed • Step 2: Gather initial critical readings through strategic plan • Step 3: Develop a hypothesis • Step 4: Conclusion 2. Which step identifies the use of basic hazmat clues such as air monitoring and placard recognition? Step 1 with Step 2 3. Which step addresses radiation? Step 2 4. What is the step that identifies three immediate hazard areas and what are they? Step 2: Detection strategy 1. Check for radiation. 2. Check for acids, bases, oxidizers, peroxides, and explosives. 3. Check for flammables/combustibles.

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CHAPTER © TFoxFoto/Shutterstock, Inc.

2

Properties and Toxicology LEARNING OBJECTIVES Upon completion of this chapter, you should be able to: • • • • • •

Summarize the scene through the use of chemical and physical properties. Identify the physical properties of matter. Identify the chemical properties of matter. Describe the dose-response relationship. Define the route of entry and the modes of toxins. Differentiate the terms of toxicology.

NFPA Citations and Competencies Citation or Competency Heading

NFPA 472 Reference

Risk-based response

3.3.57, 7.1.11, 11.1.2.2, 11.2.1, 11.3.2.1, A.5.2.4 (4), E.1.3

Physical and chemical properties

3.3.58, 5.2.2, 5.2.1.6.2, 5.2.3, 7.2.2.2, 7.2.4, 9.2.2.1, 9.3.2.1, 9.3.2.3.1, 11.2.1.4, 16.2.1, 21.1.1.1, 21.1.1.2, 21.1.1.3, 23.2.1, 23.2.2, C.2.2, C.2.3

Toxicology

7.2.5.4, 8.2.2, 11.2.1.1

Case Study On September 3, 2014, in Reno, Nevada, a flash fire occurred at a local museum injuring several children and adults attending a science demonstration. Nine individuals were transported to the hospital with burn injuries, and one required admission for continued treatment. The science demonstration consisted of the use of several salts that are burned in a watch glass with alcohol-soaked cotton balls, all spinning on a rotating tray. The fire Courtesy of Bill Hand. then produces a tornado-like, colored flame that moves up into the air. On the day of incident, boric acid was used and burned with methanol-soaked cotton balls. When the cotton balls did not ignite, more methanol was added through the use of a plastic bottle. The cotton balls were smoldering but ignited once more methanol was added. The fire flashed back into the bottle (a one-gallon container), and the methanol caught fire and sprayed from the bottle container into the audience. This is not the first incident caused by this demonstration. In 2006 at an Ohio high school, several students were severely burned and one student had to be placed into a medically induced coma so that multiple skin grafts could be performed as a result of this same demonstration. An educational video by the Chemical Safety Board (CSB) was produced in 2013 called After the Rainbow as a safety video about the incident (see http://www.youtube​ .com/watch?v=g6vR0BdRCNY) Two other times this demonstration caused injury were in 2012 in Liverpool, New York, when students and a teacher were hospitalized; and again in 2014, at a New York City high school, with additional injuries reported. Using the principles set forth in this section, answer the following questions: 1. What has happened? 2. What will or could happen? 3. What can you change?

Introduction Many students of hazardous materials chemistry look at the chemical and physical properties of matter as definitions and concepts to memorize. However, chemical and physical properties are truly the identifiers of chemical families and hazards that a family may possess. They are more than definitions or concepts, but clues to solving a possible problem. This chapter will explore how understanding physical and chemical properties can help you manage hazardous materials incidents. For example, a common-grade gasoline has been accidently spilled on the side of the road. You estimate 50 plus gallons have been spilled. The contractor has asked you to monitor the area, but you know that the vapors of gasoline are heavy and will extend far from the accident scene. The contractor would like you to establish when they have dug up enough of the dirt and fuel. You take a teaspoon and a glass of water. When you think they have dug deep enough you take a teaspoon of the dirt and mix it with the water. What should you see? If the fuel is still in the surrounding dirt, you should get sheen on the water or possibly a layer if the quantity is large enough. If the contractor has dug deep enough, the water should be clear without sheen. On the other hand, if the spilled liquid were polar, this method would not work as the substance would dissolve in the water. It is the understanding of physical and chemical properties that can determine how you can detect a given chemical or chemical family. These principles can drive how you can conduct an analysis, discover the hazards and chemical family, and predict outcomes.

Properties of Matter Our world contains a variety of substances. These substances occupy space, have mass, and are referred to as matter. Scientists study

these substances, their interactions, and their reactions. From these types of investigations, scientists are able to create new substances. Matter has phases that are commonly called states of matter: solid, liquid, and gas Figure 2-1 .

Solid

Liquid

Gas

Figure 2-1  Three states of matter: solid, liquid, and gas. © Jones & Bartlett Learning.

A solid takes up space and has certain physical properties, the most distinct of which is retaining its shape with or without a container. This shape is maintained because of attractive forces that compel a certain structure. Inherently, a solid may or may not conduct electricity, reflect light, or be hard or brittle. The melting point can be measured. In a solid, the molecules are very close in proximity to each other. Although the atoms are vibrating, the actual movement cannot be seen. Particle size is used for describing the dimensions of small particles of material. The words used for describing small particles depend on the phase of matter. Solid particles are referred to as flecks, powders, and dusts. Liquid particles are referred to as droplets, mists, and aerosols. A liquid conforms to the shape of the container it occupies. The attractive forces between molecules in a liquid sample

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Hazardous Materials Chemistry, Third Edition

are strong, but not as strong as in a solid sample. This allows molecules to adhere to each other but not be constrained to certain positions. In the liquid state, molecules are free to move, slipping by one another. This action is observed when a liquid flows out of its container. Viscosity is a measure of resistance to flow. It describes the thickness of liquids or how well they flow. A low-viscosity liquid will flow like water. The lower the viscosity, the higher the tendency for the liquid to spread. Conversely, the higher the viscosity, the slower the spread (for example, cold molasses). When referring to hydrocarbons, primarily combustible and flammable liquids, viscosity can relate to the production of static electricity. Some hydrocarbons are polarizable; in other words, they can be induced to have a negative and positive end (like a magnet). As these dipoles (tiny magnets) move over each other, they create a small charge of static electricity. Once this electricity finds a ground, a spark can be created, and if the conditions are right, the vapors can ignite.

ALERT The movement of liquids and gases can produce static electricity, a potential ignition source, thus the reason for grounding and bonding as a standard operating procedure. This tendency is observed with natural gas, propane, and gasoline, as these fuels have high vapor pressures and low flash points.

Persistence is the tendency of a material to remain in the environment for a long period of time. A chemical’s persistence depends on its mass, polarity, and other structural elements. Nonpolar compounds tend to be more persistent than polar ones. However, despite the fact that vapor pressures increase with polarity, persistent materials tend to have low vapor pressures and high boiling points (see Chapter 5, Intermolecular Interactions and Predicting Physical Properties). A gas also takes up space but can be compressed into the container in which it is carried. The attractive forces in a gas are negligible, allowing the gas to move about more freely. In the gaseous state, molecules are the farthest apart, colliding with other molecules and the container itself. In each state of matter, an increase in temperature increases the molecular movement; likewise, decreasing the temperature decreases the molecular movement. Condensation is the conversion of a gas (or vapor) into the liquid state. Energy is released into the surrounding environment as the gas moves into a liquid state. This phenomenon can best be illustrated when steam (heated water vapor) condenses on the skin; the energy that is released is fairly high, causing a severe burn. As the state of matter changes, its physical appearance may change, but its chemical composition will remain the same. For example, if you were to put an ice cube on a hot surface, you would see the solid ice melt into a liquid, and when enough thermal energy is applied, the liquid ice (water) changes into a gas (vapor).

When the natural state of a material at room temperature and atmospheric pressure is the gas phase, it is referred to as a gas. Examples include carbon monoxide, propane, and nitrogen. Vapors are the gases that are given off from flammable or volatile liquids. Gasoline and acetone are examples. Dusts are fine particles of solid matter such as coal dust, saw dust, and grain dust. Mists are liquids that have been atomized; for example, spray paint, high-pressure oil leaks, and aerosolization of nerve agents. A mist and aerosol can be thought of as the same. Particular properties related to changing phase will be discussed later. For now, it is important to remember that these characteristics are observed through experimentation (e.g., the use of wet chemistry as a detection strategy is a form of observation and experimentation). Physical properties describe the outward physical attributes a substance may have. They are the properties that can be measured or observed without changing the true identity of the matter. Many physical properties are characteristic of or intrinsic to the material. Chemical properties describe the types of reactions that a particular substance may undergo. The true identity of the matter is changed when a chemical property is observed. Thus, the only way the chemical properties of a particular substance can be identified is through a chemical reaction.

Pure Substances Versus Non-Pure Substances A pure substance is comprised of only one component. There are two categories of pure substances: element or compound. Even though a compound is made up of more than one type of element, the elements that make up a compound cannot be separated from each other by physical means. Water is a pure substance, a gallon of pure ethanol is a pure substance, and even when there are both water vapor and liquid water in a container, it is a pure substance. Non-pure substances have different components. For example, a mixture of air and liquefied air are a mixture of different elements and compounds. The difference between the air (nonpure) example and the pure (water/water vapor) is that in liquid air, you can separate the components of the air using a physical process such as condensing them out at different temperatures. In a compound, which is a pure substance, the chemical composition is fixed, while in a mixture, which is a nonpure substance, this chemical composition is not. For example, carbon dioxide is a compound. It always contains a ratio of 2 oxygen atoms per 1 carbon atom. Bronze, however, is a mixture of metals. There are samples of bronze with different ratios of copper with other metals. Typically there is about 12% tin, but there can be more or less. Because the chemical composition of bronze is not fixed, this means that bronze is not a compound, but a mixture. Mixtures can additionally be characterized as heterogeneous or homogenous Figure 2-2 . Heterogeneous describes matter existing as a mixture of elements and/or compounds that is not the same at all points. Picture a jar with steel balls and glass marbles. At some points you would observe a bunch of steel balls or glass marbles. A homogeneous mixture is a substance having the same chemical and physical properties throughout. It is sometimes referred to as a solution.

Chapter 2 Properties and Toxicology

Heterogeneous Mixture variable composition

Mixtures

Homogeneous Mixture same throughout

Matter solid liquid gas

physical methods

Elements

Pure Substances

Compounds

27

that may be exposed to the atmosphere has a relationship to how much vapor is released into the environment. The greater the surface area, the higher degree of vapor production when discussing liquids. When a gas is involved, limiting its release or changing its physical form may be the tactical procedure. If the material is in the solid form, confinement may be the action chosen in order to minimize exposures. Remember that solids in particulate form and gases are easier to decontaminate than liquid materials or slurries (a mixture of a liquid and finely divided particles). Benner’s hazmat behavior model relates these facts into predictable events. The melting point is the temperature at which a material changes from a solid to a liquid. If a material has a low melting point, you would expect it to become a liquid if the temperature is elevated. A material could possibly even become a gas if the boiling point is significantly low. (High and low are references to the ambient temperature.) This presents inherent problems of containment, confinement, and decontamination. Liquids flow freely in the absence of a container at the scene of a hazmat incident. Melting point and boiling point can be thought of as the same thing: the point at which phase change occurs Figure 2-3 . Phase changes become increasingly important when looking at your tactical options.

Figure 2-2  Types of matter can be heterogeneous or homogenous. © Jones & Bartlett Learning.

Salt crystals dissolved in water is an example of a solution. The salt ions evenly distribute through the entire solution, and the physical and chemical properties are the same at all points within the solution, making it homogeneous.

Physical Properties The physical properties of an element or compound are useful in describing the material involved. Each substance has its own set of physical properties. An ethanol molecule, for example, will always possess an individual set of chemical and physical properties. Ethanol will always look, smell, and boil like ethanol. Appearance, melting point, boiling point, density, specific gravity, vapor density, solubility, vapor pressure, viscosity, and freezing point are all examples of physical properties of matter. Some of these properties can be observed through the use of wet chemistry, air monitoring, and observations. It is from observing these conditions that you can identify a chemical group or family. These properties are characteristic of a particular element or molecule. They are qualities measured without changing the chemical makeup of the compound or molecule. Appearance is the form, size, and color of a material. The form may be described as a solid, liquid, or gas, and the particulate size can be powder, dust, or fumes. The form of the hazardous material will dictate the management strategies toward incident stabilization. For example, if the material is a liquid, leak and spill control may be the tactics of choice; surface area

Figure 2-3  A piece of ice melting. © Gabe Palmer / Alamy Stock Photo.

Which term applies—either the melting point or the freezing point—depends on the context of the physical change. If, for example, the chemical is moving from a solid to the liquid phase, the term melting point is used. If the product is going from the liquid phase into a solid phase, the term freezing point is used. A compound’s freezing point and melting point are the same temperature, it just depends on whether the temperature is reached by heating up or cooling down. The amount of heat required to move the chemical from the solid state to the liquid state and the amount of heat that must be removed to move the liquid to a solid is also the same amount and depends on the chemical itself.

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Hazardous Materials Chemistry, Third Edition

Technical Note The property used to describe how much energy it takes to actually raise the temperature of a material is its heat capacity. Chemists will either look at a material’s specific heat or molar heat capacity. For water, the specific heat of the solid (ice) is 2.03 J/g°C, for liquid water it is 4.18 J/g°C, and for steam it is 1.84 J/g°C. Notice that water is unique in that it takes more energy to heat its liquid state, which is one of the reasons water is such a benefit for fire extinguishment.

The boiling point is the temperature at which the atmospheric pressure and the vapor pressure of a liquid are equal. At this point the liquid will transform from the liquid state into the gaseous state Figure 2-4 .

VAPOR PRESSURE

BOILING POINT FLASH POINT IGNITION TEMPERATURE

Figure 2-5  Hazardous substances in a liquid state with a low boiling point have a relatively higher vapor pressure. © Jones & Bartlett Learning.

Atmospheric pressure pushes down at 14.7 psi

Water boils at 212°F

Figure 2-4  Water transforming from the liquid state into the gaseous state.

Mass, shape of the molecule, and polarity all affect how well a compound will vaporize or volatilize. In general, heavyweight compounds produce small amounts of vapor, and lightweight compounds produce significant vapor. Vapor pressure (VP) is the pressure exerted by a vapor on its liquid when the vapor is in equilibrium with the liquid; it is also the pressure a gas exerts against the sides of an enclosed container Figure 2-6 .

© Jones & Bartlett Learning.

ALERT Hazardous materials that are packaged and transported as liquids but normally exist as gases at ambient temperature must be kept under pressure or they will boil and change form. Ammonia, propane, and compressed natural gas are common examples.

Hazardous substances in a liquid state possessing a low boiling point usually have a relatively high vapor pressure Figure 2-5 . This type of material presents potential fire, reactivity, and health hazards. Conversely, the high–boiling point liquids have relatively low vapor pressures. These liquids would need an active energy source (such as heat) to convert them from the liquid state to the vapor state. Substances with high boiling points are generally safer than those with low boiling points. However, there are a few exceptions to this rule; for example, sarin has a very high boiling point but does release toxic vapors even at room ­temperature, and its toxic values are very low (in other words, very small amounts can harm).

Liquid

Figure 2-6  Vapor pressure. © Jones & Bartlett Learning.

A liquid in a closed container will be in equilibrium with its own vapor. This means that the rate that molecules turn into a vapor equals the rate that vapor is condensing back into a liquid. Once molecules are in the vapor form, they will apply a force on the container (and on the liquid phase) as collisions occur. Most liquids have a measurable vapor pressure. Vapor pressure is typically measured in millimeters of mercury (mm Hg). It is the force of a gas in a defined area and it is temperature dependent. Water, for example, has a vapor pressure of 21–25 mm Hg. Naphthalene (and its derivatives), camphor, dry ice, and iodine crystals are solids that have a vapor pressure due to a physical change called sublimation, in which the material goes directly to the vapor state from

Chapter 2 Properties and Toxicology

the solid state without going through the liquid state. (Under certain conditions, gases can move into the solid state without passing through the intermediate liquid phase. This type of phase change is called deposition.)

Technical Note The gauge on a pressure tank is calibrated to read zero when the tank is empty and is designated as psig (lb/in2 gauge). Absolute pressure is the gauge pressure plus atmospheric pressure, and is designated as psia (lb/in2 absolute).

If you are dealing with a closed container, then high–vapor pressure materials have a potential to breach the container under high temperature conditions (the explanation for outage, which occurs with the expansion of liquids). If this same container has flame impingement, the potential further increases. When considering vapor pressure, the higher the vapor pressure, the lower the boiling point. Responders should consider that interior environments are containers that can hold in the chemical. In these environments, the high vapor pressures have the potential to lead to significant respiratory injuries. Additionally, a change in oxygen within the room can occur (a 0.1 percent change on your oxygen sensor represents 5000 ppm!). Expansion ratios are the ratios of compressed gas or liquefied gas volume in the container to what the true gas volumes would be outside the container. So, for example, liquid CO2 in a dewar is at −35°F and has a pressure of 150 psig. It has a liquid density of 68.74 lb/ft3. If this is vaporized at 70°F (68°F or 20°C), which has a gas density of 0.115 lb/ft3, the expansion ratio would be 68.74/0.115 = 598 or 600:1 Table 2-1 . Density is a property that can be applied to all three states of matter. It is the mass of a substance per a given volume. For solids, it is expressed as grams per cubic centimeter; for liquids it is usually expressed in grams per milliliter; and for gases, as grams per liter. A milliliter and cubic centimeter are equivalent. A liter is a thousand times larger than a milliliter. The change in scale for the volume measurement is necessary for gases because their densities are so much smaller than liquids and solids. Density =

Mass Volume

The density of a substance is also a function of temperature in that raising the temperature decreases the density for most substances. The density therefore is a function of temperature within its specific phase. Temperature has a large effect on the density of gases, small effect on the density of liquids, and a negligible effect on the density of solids (see critical temperature, pressure, and phase diagrams in Chapter 5, Intermolecular Interactions and Predicting Physical Properties).

Table 2-1

29

Expansion Ratio

Expansion Ratio: Anhydrous ammonia 844:1 Argon 842:1 Carbon dioxide 600:1 Carbon monoxide 680:1 Chlorine 439:1 Fluorine 981:1 Helium 745:1 Hydrogen 850:1 Krypton 693:1 LNG 635:1 Methane 693:1 Neon 1445:1 Nitrogen 696:1 Oxygen 860:1 Propane 270:1 Xenon 559:1

Although the units for density typically used by scientists are those listed above, any mass unit and any volume unit can be used to express a density. For example, 1 gallon (volume) of water weighs 8.35 lb (mass). A container holding 3 gallons of water weighs roughly 25 lb. You can determine the density of water by entering that information into the formula: Density =

25 lb 3 gal

= 8.333 lb/gal Therefore, if you know that a chemical has a volume of 4 gallons and a density of 19.8 lb/gallon, then through dimensional analysis, you arrive at 79.2 lb of the substance—roughly 80 lb of a hazardous substance. The tools and appropriate level of personnel can now be anticipated for the mitigation process. Properties such as density are expressed with derived units; that is, units that are built with more than one measurement. Because you need two measurements to express a density—a mass and a volume—the unit for a density such as g/cm3 or lb/gal will always be a derived unit. Derived units can be used in dimensional analysis problems just like conversion factors. For example, say you would like to calculate the mass of a known volume of a liquid and you know the density. You would start the calculation by writing what you know, the volume and lining up the derived unit for density, so that the volume would cancel and the mass remains in the numerator. If you need to know the volume of a certain mass of material, you would start with the mass and line up the density, so that mass would cancel and the volume would remain in the numerator. In that case, you would line up the density upside down. Given  Unit ×

Desired  Unit = Desired  Unit Given  Unit

30

Hazardous Materials Chemistry, Third Edition

Example: Calculate the volume of 500.0 g benzene. The density of benzene at room temperature is 0.8765 g/cm3. Answer:

500.0 g × 1 cm 3 = 570.5 cm 3 0.8765 g

Specific gravity (SG) is the weight of a solid or liquid compared to an equal volume of water. Water has a value of 1, a dimensionless quality, in relation to the compared material. In other words, there is no unit of measurement. If the specific gravity of the tested material is less than 1, the material will float in water; greater than 1, the material will sink in water. When dealing with liquid materials in a hazmat situation, you must know if the product will float or sink in order to choose the proper spill control techniques. If, for example, the material floats on water, then the material may also produce a vapor release, leading to yet another problem. However, if the material sinks, then containment of the gaseous product is confined. By using water or foam as a barrier, the potential of fire is reduced. In either case, you must remember the environmental impact of such a decision. This principle is what is used when you employ underflow and overflow damming, and it depends on the specific gravity of the substance being dealt with. Overflow dams are used when substances are heavy and insoluble within the water environment. When the contaminant is floating on the water, underflow damming is used Figure 2-7 .

Gasoline Water Carbon Disulfide

Figure 2-7  Gasoline will float on water, whereas carbon disulfide will not. © Jones & Bartlett Learning.

You can use specific gravity similar to a density in order to calculate the volume of a spill. Suppose a railcar of phosphoric acid overturned. The consist tells us that the railcar is 198,900 lbs. You also know that that the density of water is 8.35 lbs/gal. Use dimensional analysis as follows: 198,900 lb acid ×

1  lb water 1  gal = 14, 095  gal × 1.69   lb acid 8.35lb

Vapor density (VD) is a comparison like specific gravity, but of a gas or vapor to the ambient air. Vapor density is the weight of a vapor or gas as compared to an equal volume of air. Air is given

Low Vapor Density

High Vapor Density

Figure 2-8  The dissipation of vapor depends on many factors. © Jones & Bartlett Learning.

a density of 1. If the relationship indicates a number greater than 1, then the vapor will drop or settle. If the comparison yields a number less than 1, then the vapor will rise, creating a vapor cloud. This vapor may or may not dissipate depending on the density of the gas, wind, humidity, and other related factors Figure 2-8 . Prediction of a vapor cloud depends on several factors: density of the gas; wind, wind direction, ambient temperature, and humidity; cloud cover or the lack thereof; height, amount, and duration of the discharge; and the temperature of the vapor. In the National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Industrial Hazards, vapor density is identified as RgasD, or relative gas density, which is referenced to air where air = 1. Gases with a molecular weight around 29 g/mol will have a density similar to air and a vapor density close to 1. Vapor density and vapor pressure are two of the properties considered when dealing with plume dispersion models (weather conditions and topography are also a part of plume dispersion modeling). Under certain conditions, the water vapor in the air must also be considered. This is especially true when dealing with the lighter-than-air gases in high humidity environments; for example, methane has shown qualities very much like those of liquefied petroleum gas (LPG). If you consider that vapor density is the effect of the partial pressure, molecular weight, and number of molecules present, and combine the effect of atmospheric conditions, you can see that inversion layers in the environment will shift the physical properties. The inversion layer within the environment traps the normally lighter-than-air molecule, thus giving it outward properties of heavier-than-air gases. Both specific gravity and vapor density are applications that look at the mass per unit volume, compared to that of a well known substance. From these calculations, predictions on the movement of the liquid or vapor can be made. For example,

Chapter 2 Properties and Toxicology

specific gravity is used to predict whether a substance will sink or float on water. Vapor density, like specific gravity, will predict whether a vapor will settle or rise in air. Solubility is the ability of a material to blend uniformly with another material to form a solution. In a solution, the material present in the greater amount is called the solvent, and the material present in the lesser amount is called the solute. Certain materials are miscible with each other in any proportion, and others are not, depending on the relative strength of the intermolecular interactions present. The factors affecting solubility are the polarity and amounts of the materials in solution, and sometimes the phase of the solute. Miscibility is the ability of liquids to dissolve into a uniform mixture at any ratio. Usually you think in terms of a water-miscible substance; when you say a substance is miscible in water, it means that it is soluble in water in all proportions. Meaning, you could start out with only water and pour the material into it; as you progress from mostly water to mostly the other compound, the material will blend uniformly the entire time. Solubility depends on the strength of the interactions between the particles within a potential solute compared to the strength of the interactions between the particles of the potential solute and a different material, a potential solvent. For example, sodium chloride dissolves well in water because the sum of the interactions between the sodium ion with water and the chloride ion with water are greater than those between sodium ion and chloride ion. Other compounds, such as calcium chloride, do not dissolve in water because the strength of the interaction between calcium and chloride are too strong to be broken by the interaction between those ions and the water molecules. You will see in a later chapter that the phase of a material is directly related to the strength of the interactions within a material. Polar molecules tend to stick to each other better than nonpolar molecules Figure 2-9 . This “stickiness” reduces their tendency to vaporize. Polar compounds that contain O-H and N-H in the liquid state create hydrogen bonding and a lower tendency to vaporize. Polarity has a lot to do with the solubility of a solute in a solvent. Polar substances have a partially positive end and a partially negative end, while nonpolar substances do not display this. Like

will dissolve like: polar in polar, and nonpolar in nonpolar. If the solute is a solid, the polar/nonpolar solubility rule of thumb still holds true; however, the solvent can only dissolve a limited amount of the solid. It is not infinite, as it is with many liquids. Each solute and solvent combination will have a saturation point. Above this point, the added solute will not dissolve. If you wanted to dilute carbon tetrachloride, water would not be your choice because water and carbon tetrachloride do not mix, due to the polarity difference. Carbon tetrachloride is miscible in alcohol, such that the alcohol mixture would work well for decontamination (not human decontamination, however; only equipment decontamination). The carbon tetrachloride decontamination solution containing alcohol would, of course, have to be properly disposed of. The property that describes how much solute is in a solution is its concentration. The concentration can be expressed in many different ways, but most describe an amount of solute per total amount of solution. The most common way to describe concentration in chemistry is molarity. Molarity means moles of solute per liter solution (M = mole/liter). Another common concentration unit is mass percent, which is defined as mass solute over total mass solution times 100. For example, acids are often expressed as a percent of acid in water. Muriatic acid is roughly 10 parts HCl in 90 parts water. Therefore, if you have 100 grams of total solution acid, you would have 10 grams HCl and 90 grams water. Additionally, parts per million is a concentration defined as mass solute over mass total times a million. Anything that has a measurement for solute over total solution is a concentration. The concentration unit used for gas mixtures is the mole fraction. Mole fraction is the number of moles of the solute divided by the total number of moles of all components in the mixture. A mole percent is simply a mole fraction times 100. Lower explosive limits (LELs) and upper explosive limits (UELs) are expressed in mole percents (i.e., mole fractions times 100).

Technical Note Concentration Units Mass percent =

-

-

+

+

ATTRACT

ppm =

ppb =

-

+

REPULSE

+

-

Figure 2-9  Molecules can have positive and negative ends, depending on the individual atom’s electronegativity. Each acts like a tiny magnet. © Jones & Bartlett Learning.

31

mass of solute

mass of solute total mass of solution

× 106

mass of solute total mass of solution

Molarity (M) =

Mole fraction of solute =

× 106

total mass of solution

× 109

moles of solute liter of solution moles of solute

total moles of all components

32

Hazardous Materials Chemistry, Third Edition

Remember that mass percent, parts per million, parts per billion, and parts per trillion all differ by a factor of 10, so when referencing information, make sure that the appropriate measurement is referenced. Whenever a solution (or solubility) is discussed, it is a discussion of a homogeneous mixture. If you have an acid diluted with water, the runoff will be a mixture of the acid and the water.

ALERT Alcohol decontamination should not be used on people, because it can decrease body temperature with as little as 10 percent of body surface area exposed. It can also increase absorption of a chemical. Additionally, if a substance has a low water-solubility point, it may be soluble in lipids or proteins, adding to the health hazard.

The concept of dilution is relevant to the decontamination process. Although water is the primary solution for decontamination, the amount of water needed in some cases may be more than would be expected. For example, when dealing with corrosive materials, dilution as a method of neutralization would

Technical Note As a practical example and application of these principles, the Five Step Field ID Method, HazCat Kit, and the HazChem Kit utilize principles of chemical and physical properties to identify families of chemicals Figure 2-10 . From this deduction, further analysis can be performed to give logical characterization possibilities. These procedures are sometimes referred to as wet chemistry.

Figure 2-10  The HazChem Kit. Courtesy of HazTech Systems, Inc.

require an extensive amount of water. One liter of a fluid that has a pH of 1 would require a total volume of 1,000,000 liters of water to move the pH to around 7. When liquids are mixed the total volume increases. When polar liquids are added to water (which is also polar), a polar solution is formed of greater volume. Such is the case when a gallon of alcohol is on fire and an attempt to extinguish it using water is made. The result would be that the total volume of the alcohol and the water that was used would be on fire. This sort of situation is, in fact, a dilution problem. It takes a lot of water to dilute the alcohol to a point where vaporization no longer occurs, roughly 10 times more per volume. Solubility also comes into play when a toxic substance is placed into solution for dispersion of the material. Not only does its solubility give the material greater distribution power, it also increases the health hazard in terms of skin and mucosa absorption.

Chemical Properties As previously stated, chemical properties are the intrinsic characteristics of a substance that describe its tendency to undergo chemical changes. These characteristics include properties such as heat of combustion, reactivity, and flash point. All chemicals try to reach a state of stability. It is this desired condition that creates the need to undergo a chemical reaction. The reaction takes place because of the specific architecture of the elements or compounds within the surrounding environment. Problem Set 2-1 1. The property that describes the force exerted on by a vapor on its liquid when in equilibrium with it or the force exerted on the sides of the enclosed container is: a. vapor density. b. vapor pressure. c. relative vapor density. d. liquid density. 2. A substance that has a predominate positive end and predominate negative end is said to be: a. a positive hydronium. b. highly volatile. c. a polar substance. d. neutral. 3. The liquefied gas volume that is within a container as compared to the gas volume outside the container is called: a. the flash point. b. the ignition temperature. c. expansion ratios. d. lower explosive limits. 4. The solute: a. is the material in greater amount. b. is the material in lesser amount. c. dissolves uniformly. d. is miscible.

33

Chapter 2 Properties and Toxicology

The color of smoke can give a clue regarding the substance involved in an incident. Consider that smoke is a primary indicator of a reaction. Thick, black smoke is characteristic of benzene and petroleum products; white smoke is characteristic of hydrochloric acid and phosphorus-type products; gray-white-brown smoke is characteristic of nitrocellulose; greenish-yellow smoke is characteristic of chlorine; gray-brown-yellow/red smoke is characteristic of nitric acid and bromine, and purple smoke is characteristic of iodine. Ignition temperature is the minimum temperature at which a material will ignite and sustain combustion without a continuing outside source of ignition. The heat of combustion relates to a reaction in which the products are completely oxidized or in which complete combustion takes place in air. It is the heat liberated during the reaction. The flash point of a material is that minimum temperature under which a liquid will give off vapors to form an ignitable mixture in air, provided that an ignition source is present. So when a liquid produces enough vapor to flash when an ignition source is available but not sustain combustion, this condition is called its flash point Figure 2-11 . Flash point and ignition temperatures can be in close proximity on the temperature scale. (This concept is most important when dealing with organic compounds.) Flammable ranges or limits represent the minimum and maximum concentration of a chemical in the air that is favorable for ignition to occur. The LEL is the minimum concentration

ALERT When the boiling point is lower than the ambient temperature, vapors are produced. A lower boiling point equals a low flash point and higher possibility of a dangerous atmosphere.

of vapor in the air that can ignite. The UEL is the maximum concentration in the air that can ignite. When a gas is released into the environment, the wind, ambient temperature, topography, and availability of an ignition source play roles in the chemical’s ability to ignite. If you could measure the gas as it is traveling through the air, you would discover three distinct areas of concentration. First, the vapor would be “rich” within this atmosphere, or at a high concentration, around the container that originally held the material. Even if an ignition source were available, the gas would not burn in this area. As you continued your measurements moving away from the container, you would find an area that has the perfect percentage of air and chemical vapor concentration to permit ignition. Farthest from the source, you would measure the concentration of the chemical and find it to be “lean;” there would not be enough vapor to ignite in relation to oxygen. It would not burn even if there were an ignition source available. However, one must also remember that around the flammable limits (usually just below or at the lower explosive limit) may lay the toxic ranges. As shown in Figure 2-12 , whether or not a substance enters the flammability range is temperature dependent. As temperature increases, vaporization increases. Although, 10 percent of the LEL is below the flammability range, it is a warning that you may be entering a flammable environment. The wider the flammability range, the more dangerous the chemical. In general, LELs for flammable liquids are 1–3 percent and for flammable gases, 3–6 percent.

– 43°F Flash Point (Gasoline)

UEL

FLAMMABLE RANGE LEL 10% OF LEL

0% TEMPERATURE

Figure 2-11  Gasoline at −43°F gives off sufficient vapor to result in a flash point when an ignition source is present.

Figure 2-12  Range of flammability.

© Jones & Bartlett Learning.

© Jones & Bartlett Learning.

VAPOR PRESSURE

PERCENTAGE OF VAPOR IN AIR

100%

Hazardous Materials Chemistry, Third Edition

These concentration bounds or limits are called the flammable or explosive limits and are different for each chemical compound. The difference depends on the vapors that are produced, and thus the range of flammability. If, for example, the UEL range were, say, 98 percent, the explosive potential would be very real due to the wide flammable range that this particular chemical may have. Above this 98 percent point, the concentration of the chemical vapors within the atmosphere may be too high or rich to burn. However, one would have to transcend through the flammable range in order to reach this rich environment. Consider ethylene oxide as an example, with an explosive range of 1–99 percent, or acetylene at 2–100 percent. The UEL in these cases cannot be exceeded. They have potentially extremely hazardous environments before the UEL is reached, and reaching the UEL becomes hazardous. All compounds with wide flammable ranges pose this potential problem Figure 2-13 .

BOILING POINT

VAPOR PRESSURE

Residue in tanks permits a 1 percent content of material. The following is a simple relationship of how much could be within a tank based on size versus 99 percent “empty”: 50,000 = 500 gallons; 30,000 = 300 gallons; 5000 = 50 gallons; 3000 = 30 gallons; 1000 = 10 gallons.

FLASH POINT

MELTING POINT

LEL IGNITION TEMPERATURE UEL

SOLID OR LIQUID As a general rule, for every 10˚C temperature increase, the reaction doubles.

ALERT

VAPOR DENSITY

GAS

SPECIFIC GRAVITY

material is a solid, heat impinging on the material will cause it to move from a solid to a liquid and then into the gas phase. Once gas, which has a vapor pressure and density, is produced, a mixture must be attained for it to then move into a flash point state through its LEL and UEL. At some point, if not cooled, it will continue to repeat the cycle, becoming more intense with every repetition until the fuel or oxygen is consumed, or heat is reduced.

If a reaction continues, gas production will continue, and with fire present, the fire will continue until the fuel is consumed.

Figure 2-13  The fire cycle. Courtesy of Armando Bevelacqua.

The fire cycle summarizes the physical and chemical properties observed in a potential fuel as it approaches the conditions where it can ignite and sustain combustion. If, for example, a

Heat Transfer Some basic principles that apply in connection with heat and fire are conduction, convection, and radiation Figure 2-14 . Conduction is the mechanism by which heat is transferred between materials in contact with one another. Conduction is affected by the material’s total thickness, cross-section, and ability to transfer heat. It can be thought of as a balance between the thermal energy that is being given to the material and the amount of heat that can be absorbed. Increasing surface area around which heat is being liberated can increase conduction. Convection is the mechanism of heat transference by the movement of a gas or liquid. It is technically the heat that transfers through a gas or liquid medium at the point of contact with the

CONVECTION

RADIATION

CONDUCTION

34

FIRE

Figure 2-14  The heat from a fire can travel in three ways, individually or in combination, by convection, conduction, or radiation. Courtesy of Armando Bevelacqua.

Chapter 2 Properties and Toxicology

container. Radiation is the outward movement of heat from a source via electromagnetic waves. It is the mechanism by which heat is transferred between two objects that are not touching but are in relatively close proximity to one another. Thermal conductivity is a measure of the amount of heat a material can carry. This principle can be used in measurement of gases and how much conductively passes through a gas. The Gas Ranger meter uses this principle of conductivity. Once the LEL reaches 100 percent (on the catalytic bead side), the conductivity meter takes over. The reading then assumes that any gas other than air is a flammable gas. The conductivity of methane relative to air is 1.22, while carbon dioxide is 0.59. A conductivity meter doesn’t care whether the conductivity of the gas that’s being measured is higher or lower; it just knows it’s different than air. Conductivity meters m ­ easure the change in conductivity of the gas relative to that of air.

talking of the strength of an acid or base. A strong acid is a ­compound where every molecule will donate H+. A weak acid is a compound where only some molecules donate H+. The same concept applies to bases. A strong base dissociates completely. Only some molecules of a weak base accept H+ (see Chapter 11, Tools of the Trade). It is possible to have an acid solution lower than a pH of 0 or a base solution higher than a pH of 14 Figure 2-15 . Since pH is –log[H3O+], where the hydronium ion concentration is in molarity, any strong acid with a molarity higher than 1M (Molarity = mol/L) will have a pH lower than 1 Figure 2-16 . For example, concentrated nitric acid is typically 70 percent HNO3 or roughly 16 M. The –log16 = –1.2. Basic solutions that have a concentration of hydroxide greater than 1 M would have a pH greater than 14 Figure 2-17 . [H1]

Problem Set 2-2 1. The flammable ranges: a. represent the maximum concentrations within an environment. b. represent the minimum concentrations within an environment. c. represent both the maximum and minimum concentrations within an environment. d. are dependent on ignition source. 2. Which is the minimum temperature at which a material will ignite and sustain combustion? a. Flash point b. Ignition temperature c. LEL d. UEL 3. What is the mechanism by which heat is transferred between materials? a. Convection b. Radiation c. Conduction d. Heat transfer 4. What do we call the point at which we have a minimum ratio of flammable gas/vapor to air? a. LEL b. UEL c. Explosive limits d. Convection

pH Ion Scale The pH (positive hydronium ion) scale is used to measure how acidic or basic an aqueous solution is. pH is defined as the negative log of the hydronium ion concentration in molarity (moles of H3O+ per liter solution). An acid–base reaction is an ionization reaction. An acid will donate H+ (hydrogen ion) to water to create a H3O+ ion (hydronium) within a solution, and a base will accept H+ from water to produce a OH– (hydroxide) in an aqueous solution. It is the relative tendency of a substance to react in such a way with water that you are discussing when

35

pH

Examples

1020

0

Hydrochloric acid

1021

1

Lemon juice

1022

2

Stomach acid

1023

3

Vinegar, cola, beer

1024

4

1025

5

Tomatoes, champagne Peat bogs Black coffee

26

6

1027

7

1028

8

Urine Saliva (6.5) Distilled water Human blood (7.4) Seawater

1029

9

Baking soda

10210

10

Great Salt Lake

10211

11

Household ammonia

10212

12

Bicarbonate of soda

10213

13

Oven cleaner

10214

14

Sodium hydroxide (NaOH)

10

Acid

Base

Figure 2-15  The pH scale. © Jones & Bartlett Learning.

Extremely dangerous acids and bases include the ones that are anhydrous—without water. An acid with an acidity activity greater than 100 percent sulfuric acid, also known as oleum, fits into this category. A base such as anhydrous ammonia, because of its anhydrous and gas qualities, make it dangerous for responders. (If you have an acid without a water component, the reading from pH paper is meaningless. This is one reason why you should wet pH paper during initial entries.) Residue in tanks permits a 1 percent content of material. The following is a simple relationship of how much could be within a tank based on size versus 99 percent “empty”: 50,000 = 500

36

Hazardous Materials Chemistry, Third Edition

not occur to completion. A chemist would write the equation with a double-sided arrow. CH3COOH(aq) ∆ CH3COO− (aq) + H+(aq) or CH3COO(aq) + H2O(l) ∆ CH3COOH− (aq) + H3O+(aq)

Figure 2-16  An acid. © Jones & Bartlett Learning. Photographed by Glen E. Ellman.

Despite being weak, there could exist very concentrated solutions of weak acid that are very dangerous. For example, hydrofluoric acid (HF) is considered a weak acid to a chemist simply because HF does not dissociate to completion. However, most incidents involving HF involve concentrated solutions that are extremely dangerous. A hazardous materials technician would treat the incident with the same (if not more) level of caution that he or she would at an incident involving a concentrated solution of a strong acid. Therefore, although concentration, or the amount of acid dissolved in water, is not the property that classifies an acid solution as strong or weak to a chemist, it is the concentration of the acid solution that is most important to a hazardous materials technician.

Toxicology

© Jones & Bartlett Learning. Photographed by Glen E. Ellman.

gallons; 30,000 = 300 gallons; 5000 = 50 gallons; 3000 = 30 gallons; 1000 = 10 gallons. A chemist will classify an acid as being strong or weak depending on the extent to which that acid dissociates in water to produce hydronium. For example, hydrochloric acid is considered a strong acid because the following dissociation occurs to completion: HCl (aq) → H+(aq) + Cl−(aq) or

100 80 % Responding

Figure 2-17  A base.

Toxicology, for our purposes, must be thought of as the study of a biochemical reaction: a chemical compound that is foreign to the human body is reacting through a biometabolic pathway and causing an effect. That effect may be slight or it may be catastrophic. Most of the time when one interacts with chemicals, the dose is very small, allowing the body to compensate for the exposure. However, if the insult is large, that is, the exposure is of a greater magnitude than what the body can metabolize, an effect from the exposure is observed. This effect is called the dose response Figure 2-18 .

60 50% 40 20

HCl(aq) + H2O(l) → H3O+(aq) + Cl−(aq) There could exist very dilute solutions of strong acid that are not very dangerous. For example, a solution that contains 1.0 × 10−5 M HCl has a pH of 5, and would not be dangerous, even though HCl is a strong acid. Conversely, a weak acid is one that does not dissociate to completion in water. The dissociation of a weak acid reaches equilibrium. For example, acetic acid is a weak acid because when dissolved in water, the dissociation of H+ to form hydronium does

0 10

100

LD50

1000

10000

Dose (log scale)

Figure 2-18  From a hazmat perspective, you cannot be sure where on the curve an individual may have a response. Factors such as age, previous exposure, race, sex, and immunity all play a role in the dose response. © Jones & Bartlett Learning.

Chapter 2 Properties and Toxicology

There are thousands of chemicals in our daily environment, and millions within the environment as a whole. Some are naturally occurring and some are man-made (synthetic). Because of this vast quantity of chemicals, it is sometimes hard to link the cause and effect to an exposure. Did the exposure (the cause) lead to the medical problem (the effect)? The fundamental reason this relationship is so hard to establish is the difficulty in understanding the human (and animal) physiological functioning on the biochemical (cellular and tissue) level. Phillipus Paracelsus was the first to recognize this dose-response relationship in the sixteenth century as to the quantity of a poison that is harmful. He is considered the father of toxicology.

Routes of Entry There are four basic considerations when it comes to exposure: 1. The amount of the chemical, which includes the concentration (how much are you exposed to?) 2. Rate of absorption, which has to do with the shape and polarity of the chemical (absorption and distribution) 3. Rate of detoxification, which depends on the organism’s metabolism (phase I and phase II) 4. Rate of excretion, which is conditional to the end result of the metabolic pathway Exposure also deals with the route by which the chemical may enter the body, or routes of entry Figure 2-19 . These routes can share components; for example, inhalation will include a certain degree of absorption quality. You can generalize exposure routes into four basic modes: 1. Absorption 2. Ingestion 3. Inhalation 4. Injection

37

Absorption commonly refers to dermal contact, but it can occur in any organ. Inhalation injuries include absorption across the alveolar membrane through or into the bloodstream. Thus, the agent is transported throughout the body, affecting numerous organs and tissues as it passes. Again, absorption is normally thought of as the transmission of a chemical through the skin or mucous membranes; however, it may occur within the respiratory tract. For most workers, the absorption route of entry involves the highest percentage of injury. Ingestion is the intake of a solid or liquid into the gastrointestinal tract. This route is commonly referred to as oral ingestion. Here, as elsewhere in the body, a certain degree of absorption does take place because ingestion is actually an absorption relationship within the gastrointestinal tract. At a hazardous materials incident, the process is usually seen during the rehabilitation and decontamination phases of the incident; for example, eating, drinking, or smoking prior to effective decontamination facilitates ingestion. Inhalation is the intake and absorption of a gas (fume, aerosol, particle, dust, and so forth) into the lungs, where it is distributed to the rest of the body. Inhalation is the most common exposure route. Because the lungs can move a tremendous volume of air as you breathe, a high level of respiratory protection is mandated in hazmat situations. For most workers, the respiratory absorption route of entry involves the highest percentage of injury. Injection is the forced introduction of a substance into the body. Although the incidence of such an exposure at a chemical accident is rare, the possibility is always present. Usually you see this type of exposure during the entry phase of the incident. Perhaps a team member is not aware of a sharp object (or the open valve in a high-pressure cylinder) and it penetrates the suit and the skin, introducing the chemical via injection into the body, or more commonly by EMS during IV placement.

Types of Exposure

A. Inhalation

B. Absorption

C. Ingestion

D. Injection

Figure 2-19  Four ways a chemical substance can enter the body. © Jones & Bartlett Learning.

Acute exposure refers to a sudden onset of symptoms or an exclusive short-term episode. It relates to the hazardous materials exposure as a single event that causes an injury. This single exposure is usually of short duration. It is sometimes classified as nonpredictable. This single dose either occurs within a 24-hour period, or as a constant exposure for 24 hours or less. In certain cases, it could be multiple exposures within the 24-hour time frame. Acute also refers to the rapid onset of symptoms after such exposure. Subchronic and subacute are terms that have been used interchangeably in the literature to describe the same type of exposure. However, in order to be correct, the appropriate term is subchronic exposure. This type of exposure is a recurring acute exposure that, in total, happens during approximately 10 percent of the organism’s life span. Chronic exposure is a long-term exposure, usually recurring during 80 percent of the total life span of the organism.

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Hazardous Materials Chemistry, Third Edition

Chronic effects are much harder to establish than the acute effects because of the many factors involved. Our understanding of toxicological responses and knowledge of biochemistry is limited. Chronic exposure may affect not only the exposed organism, but its offspring as well. In addition, the cumulative effect of chronic exposure may lead to hyper-or hyposensitivity within the organism.

Exposure Limits In the United States, the recommended threshold limit values (TLVs) are established by the American Conference of Governmental Industrial Hygienists (ACGIH). The recommended exposure limits (RELs) are established by the NIOSH. Workplace environment exposure limits (WEELs) are established by the American Industrial Hygiene Association (AIHA), with permissible exposure limits (PELs; also seen as published or personal exposure limits) established by the Department of Labor Occupational Safety and Health Administration (OSHA). The numbers that each United States organization utilizes are roughly the same. In some instances the testing procedures may vary; however, for the most part, the TLV standards of the ACGIH, a trademark for the ACGIH, are customarily used as the industry standard. The committee that introduced these levels has stated that the TLVs are not intended for the following uses: • To describe the level of hazard as it relates to the toxicity for a chemical or group of chemicals • For the evaluation of air pollutants • For the decision of an extended work period within an environment or when estimating the toxic capacity of a chemical • To describe the cause and effect of a chemical substance • If the working conditions are greatly different from those within the United States work environment

Reducing Potential Exposures ACGIH’s only intended purpose was to establish safe working conditions in the United States for those individuals who may become exposed on a daily basis. They were not intended to be used by emergency response personnel at the scene of a hazardous materials accident. However, they are the only numerical indicators of exposure limits that exist for chemicals. Remember that these standards were developed for the long-term exposure found in industrial processes and relate to the worker who becomes involved with these chemicals. These numbers should not be viewed as absolutes, but rather as indicators of an estimated level of harm. All toxicological data used should be scrutinized during the decision-making process. By utilizing these values in association with all other toxicological data, and through your understanding of chemistry, you can plan your safe level and manage the incident with one objective: to reduce the possibility of exposure to response personnel.

Toxic Values Although many of the chemical toxic values are given in mg/m3 (solids), some of the literature will give conversion ­factors for mg/m3 (typically for liquids) to ppm. For a ballpark ­conversion to ppm estimate, you can use the following formula: ppm = mg/m3 × 24.45/MW, where ppm is parts per million and MW is the molecular weight. Parts per million (ppm) can be visualized as 1 ounce of cream in 7,500 gallons of coffee, or 1 percent is equal to 10,000 ppm or 1 inch per 16 miles. A ppb, or part per billion, is 1 ounce of cream in 3,780,000 gallons of coffee. You can utilize these numbers with associated information because most of them were established for safe working conditions without the need of personal protective equipment (PPE). At an incident, some level of PPE is nearly always worn, thereby increasing the margin of safety. However, allowances must be made for all of the values, considering the testing parameters under which they were derived. The TLV is the level of exposure that starts to produce an effect. Below this level, there will not be any discernible effects if a worker is exposed to a chemical repeatedly. Most of these values refer to airborne concentrations and are based on exposure during a standard workweek. The ACGIHs TLV-TWA is based on an 8-hour day, 5 days a week to give a 40-hour workweek. OSHA also considers this time frame as the exposure standard. In both cases they refer to this level as the TLV-TWA, in which TWA is the time-weighted average, or the average concentration of a chemical that most workers will be exposed to during the normal 40-hour workweek, at 8 hours a day. NIOSH denotes a TLV-TWA based on a 10-hour workday, 4 days a week, to give the 40-hour workweek. Based as it is on the traditional 8-hour day and 40-hour workweek, the TLV-TWA cannot be applied to conditions of nontraditional schedules, such as one 8-hour day a week plus two 16-hour days on weekends to arrive at 40 hours. Its values were designed to take into consideration exposure to a chemical for the length of a day, provided that the maximum TLV-TWA was not reached, and time off allows the body to eliminate any stored chemicals. So, in 1976, the ACGIH committee that designed the TLV came up with short-term exposure limits (STELs), a weighted 15-minute event. It is sometimes referred to as the emergency exposure limit (EEL). The STEL refers to an exposure that occurs for only 15 minutes and is not repeated more than four times a day. Each 15-minute exposure event is interrupted by a 60-minute non-exposure environment. Thus, STEL applies to an individual exposed to a chemical for 15 minutes with a 1-hour break between exposures, not to exceed four times within an 8-hour day. More recently, the ACGIH recommended the use of excursion limits (ELs), which are weighted averages with the exposure time not to exceed five times the published 8-hour TWA. This exposure can only occur for 30 minutes within any one workday that is 8 hours in duration. Therefore, ELs are more realistic than the STEL.

Chapter 2 Properties and Toxicology

The ACGIH has defined other limit values: TLV-s and TLV-c, the threshold limit values for absorption through the skin (s), and for ceiling levels (c). At ceiling levels, exposure ensures death if not properly protected. Ceiling levels should never be exceeded without evaluating the PPE required. This level is similar to NIOSH’s immediately dangerous to life and health (IDLH) value. OSHA, which is a branch of the Department of Labor, has, for the most part, adopted the ACGIH TLVs as their own PELs. OSHA and NIOSH define IDLH as the maximum airborne concentration that an individual could escape from within 30 minutes without sustaining any adverse effects. The IDLH (and TLV-c) give us a level at which the only form of protection is that of full encapsulation with self-contained breathing apparatus. In some cases, the skin absorption factor must also be evaluated. It is recommended that IDLH atmospheres not be entered unless the individual is properly trained and the appropriate protective garments are donned. Individuals caught unconscious within an IDLH environment will more than likely have died by the time the hazardous materials team can make entry. NIOSH defines IDLH as an exposure to airborne contaminants that is “likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.” The OSHA definition is “in the absence of airborne contaminates to include oxygen-deficient circumstances,” which under the regulation (1910.134(b)) defines the term as “an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual’s ability to escape from a dangerous atmosphere.” Working with IDLH or LClo values is problematic for several reasons. For one thing, it only applies to the healthy, young, active male working population. It does not account for the possibility of hypersensitive or hyposensitive individuals. Even though its values are based on the effects that may occur if there happened to be a 30-minutes exposure, this criterion does not mean that one can stay in the atmosphere for 30 minutes without ill effect (even though the 30-minute time frame is not in the definition, many chemicals have time frames from which you should recognize self removal). The ACGIH exposure limits terminology is as follows: TLV (threshold limit value): The level of exposure to airborne contaminants that starts to produce an observable effect. TWA (time-weighted average): A refinement of TLV to take into account an 8-hour day, 40-hour workweek with repeated exposure without any adverse effects. STEL (short-term exposure limit): A TLV restricted to a 15-minute event in which the worker is exposed to the chemical continuously. The event must not have any of the following effects: any irritation, chronic tissue damage, or the impairment of a self-rescue. EL (excursion limit): An average exposure not to exceed the published 8-hour TWA, and not to occur for more than 30 minutes on any workday.

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TLV-s: Identifies a material that is absorbed through the skin. TLV-c: A ceiling level for exposure. Many discussions on toxicology use Haber’s Law, which gives a dose over time with equivalents. For example, 10 minutes at 8 mg/m3 = 2 minutes at 40 mg/m3 = 1 minutes at 80 mg/m3. All are equal to 80 mg-min/m3. Finally, NIOSH does not have values for all IDLH toxic chemicals. Any IDLH value should be used only as a guideline and not as an absolute level. The Environmental Protection Agency (EPA) utilizes the values as presented from ACGIH, NIOSH, and OSHA. It is mostly concerned with the impact that a chemical may have on the environment and the organisms that make up that environment. The EPA has developed Emergency Response Planning Guidelines (ERPGs), as follows: • ERPG-1: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing anything other than mild, transient adverse health effects or perceiving a clearly defined objectionable odor. • ERPG-2: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action. • ERPG-3: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects. The OSHA exposure limits terminology is as follows: PEL (permissible, published, or personal exposure level): Has the same meaning as TLV-TWA. IDLH (immediately dangerous to life and health): The maximum airborne contamination that an individual could escape without any side effects (NIOSH defines IDLH as an exposure to airborne contaminants that is “likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.” The OSHA definition is “in the absence of airborne contaminates to include oxygen-deficient circumstances.”). CL (ceiling level): Similar to TLV-c. NIOSH’s REL is similar to PEL and TLV-TWA, where RELs are often more conservative than the TLV. In addition to the ERPGs, the EPA has also developed TEELs (temporary emergency exposure limits). They are the following: • TEEL-0: The threshold concentration below which most people will experience no appreciable risk of health effects.

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Hazardous Materials Chemistry, Third Edition

• TEEL-1: The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild, transient adverse health effects or perceiving a clearly defined objectionable odor. • TEEL-2: The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action. • TEEL-3: The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing life-threatening health effects. Because short-term and long-term exposure limits sometimes vary, the EPA has proposed a new threshold exposure limit called Acute Exposure Guideline Level (AEGL). This represents threshold exposure limits for the general public and is applicable to emergency response exposures for periods ranging from 10 minutes to 8 hours (AEGL-1, AEGL-2, and AEGL-3), and will be distinguished by varying degrees of severity of toxic effects. It is believed that the recommended exposure levels are applicable to the general population, including infants and children and other individuals who may be sensitive and susceptible. With increasing airborne concentrations above each AEGL level, there is a progressive increase in the likelihood of occurrence and the severity of effects described for each corresponding AEGL level. Although the AEGL values represent threshold levels for the general public, including sensitive populations, it is recognized that certain individuals subject to unique metabolic responses could experience the effects described at concentrations below the corresponding AEGLs level. The AEGLs are defined in Table 2-2 .

Table 2-2

Exposure Limits Summary

Organization

Exposure Abbreviation

Definition

ACGIH

TLV

8-hr time-weighted average

ACGIH

STEL

15-min time-weighted average

OSHA

PEL

8-hr time-weighted average

NIOSH

REL

10-hr time-weighted average

NIOSH

IDLH

Dangerous to immediate threat to life; escape is possible without permanent injury

EPA

ERPG

Planning guidance

EPA

TEEL

Planning guidance

EPA

AEGL

Guidance for emergency responders with exposure durations

• AEGL-1 is the airborne concentration (in ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic, non-sensory effects. However, the effects are not disabling, and are transient and reversible on cessation of exposure. Airborne concentrations below AEGL-1 represent exposure levels that could produce mild and progressively increasing odor, taste, and sensory irritation, or certain non-symptomatic, non-sensory effects. • AEGL-2 is the airborne concentration (in ppm or mg/ m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting, adverse health effects, or an impaired ability to escape. • AEGL-3 is the airborne concentration (in ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death. The last group of exposure-limit toxicological terms that will be discussed are related to the dose-response of drugs as they relate to chemicals. If the chemical in question is airborne and primarily an inhalation hazard, you would want to know its lethal concentration (LC). If the chemical poses a threat other than an inhalation injury, you would want to know its lethal dose (LD). Both quantities describe the effect on a percentage of the population. A 50 percent death rate after the introduction of a chemical inhalation hazard is denoted as lethal concentration 50 (LC50). The lethal dose 50 (LD50) is the calculation of an expected 50 percent death toll after an exposure to a chemical that may or may not include an inhalation injury. Similarly, an LC25 or LD25 is a 25 percent death toll within the tested population. Dose-response exposure terminology is as follows: LClo: The lowest concentration of airborne contaminates that can cause injury. LDlo: The lowest dose (solid/liquid) that can cause an injury. LC50: A level of concentration at which 50 percent of the test population died from the introduction of this ­airborne contaminate. LD50: A dosage level at which 50 percent of the tested ­population died from the introduction of this chemical as a solid or liquid. LCT50: A statistically derived LC50 (LDT50 is a statistically derived lethal dose—Haber’s Law). MAC: The maximum allowable concentration (European, also MAK). RD50: A 50 percent calculated concentration of respiratory depression (RD) in response to an irritant, over a 10- to 15- minute time frame. The number that is given with the associated LC or LD is relative. In general, the smaller the number, the more toxic

Chapter 2 Properties and Toxicology

the chemical. Likewise, the greater the number the less toxic it is. The reference literature that enumerates the LD and LC for humans actually use statistical extrapolations. They are derived from the mean LD or the average lethal dose (ALD) or concentration. From there they are calculated to the human experience. At times this value is referred to as the toxic dose low (TDL), or the toxic concentration low (TCL). As previously noted, the concentration denotes the inhalation injury and the dose denotes absorption of a liquid or solid either through the skin or by ingestion. Not everyone will react to a toxin in the same way. For this reason, 50 percent of the population is the standard for LDs and LCs. Also, the problem of extrapolation from an animal population to the human is an assumption. For example, if two chemicals have an LD50 of 1000 ppm and 10,000 ppm, respectively, the first chemical is more toxic. However, if a third chemical is observed with an LD50 of 4000 ppm but it has a higher percentage of death at the beginning of the curve, then hyposensitive individuals will become affected early on. Overall, even though the LDs may have escalating numbers, it is the beginning of the curve that truly designates the acute toxicity. One must remember that for the most part, these are values that are observed in the laboratory under controllable conditions; these tests are not done on human beings. However, there are a few cases in which the human experience has been documented. In these cases, the reference literature usually denotes this by placing the chemical-exposure animal in parentheses. Problem Set 2-3 1. List four considerations as they pertain to an exposure. a. Absorption, inhalation, ingestion, injection b. Rate of absorption, rate of detoxification, rate of excretion, ingestion c. Inhalation, absorption, concentration, excretion d. Concentration, absorption, detoxification, excretion 2. List the modes of exposure. a. Absorption, inhalation, ingestion, injection b. Rate of absorption, rate of detoxification, rate of excretion, ingestion c. Inhalation, absorption, concentration, excretion d. Concentration, absorption, detoxification, excretion 3. Acute exposure refers to: a. an exposure lasting 10 percent of a lifespan. b. an exposure lasting 75 percent of a lifespan. c. an exposure lasting 24 hours or less. d. an exposure lasting 48 hours or less. 4. Which of the following numbers would be used in an emergency response? a. TLV b. STEL c. IDLH d. All the above

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In the beginning of this chapter, how to predict an outcome was discussed. Predictions can sometimes involve the chemical and physical properties of a substance, and sometimes predictions encompass what a container may do with outside influences. The entire incident or event, however, has not yet been described or addressed. There are three components within an event: seen characterization, hazard characterization, and exposure characterization, and each of these characterizations has additional components that the responder can use to identify other elements of the incident. Under the heading of toxicology, responders use the exposure characterization to identify the potential toxidromes that may be affecting a victim of a hazardous materials event.

Toxicological Considerations Reactions in the Body Substances can be inherently toxic or converted into toxic compounds in the body during the metabolic process (protoxic). As previously discussed, shape, polarity, and orientation in space (shape) all have an effect on a chemical and its physical properties. These same factors also affect the metabolism of that chemical, which may manipulate the chemical into a toxic or nontoxic compound. Chemicals also have the ability to enhance, cancel, support, and give an additive response to toxicity. Human beings are made mostly of water. All substances excreted from our body are water soluble. In order for an introduced substance to be excreted from the body via the kidneys, it must be water soluble. Remember that polarity limits the solubility to like substances. With some chemicals, the body looks for a way to convert the nonpolar (thus nonsoluble) substance into a polar molecule so that the excretory process can handle the metabolite. Unfortunately, sometimes a nonpolar, nontoxic substance is converted into a polar and possibly toxic substance. In order for the body to manipulate the nonpolar substance into a polar substance, several reactions must take place. During this reaction cycle, a toxic intermediate compound may be produced that starts to destroy the required chemical processes in the body. The primary reason for these reactions are due to what are called Phase I and Phase II reactions. In a Phase I reaction, you have to remember that the chemistry of the functional groups depends on the surrounding available compounds. An assortment of products can be created from a single compound. Now multiply the possibilities if you have several chemicals invading the body (which possesses its own variety of chemicals). In some metabolic pathways, the Phase I reaction takes a highly active polar chemical and converts it into a lipophilic toxic chemical. Once this chemical becomes modified, the product is a water-soluble compound. However, the solubility is relative to the original compound; if the compound is slightly soluble, then the product will more than likely have high water-soluble qualities. Conversely, if the compound is not soluble in water

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Hazardous Materials Chemistry, Third Edition

at all, then, although the product compound may have water-soluble qualities, it may not be as soluble as is necessary for the excretory process to handle. The following are examples of Phase I reduction reactions: Aldehyde R–CHO RCH2OH Ketone R–CO–R′ RCH(OH)R′ Alkene C=C –CHCH(OH) Nitro groups R–NO2 R–NO; RNH2; RNH–OH If the substance does not become as soluble as it needs to be for the kidney to take over, then an active site is placed on the compound so that the substance can be eliminated through the kidneys. This attachment of an active site is termed the Phase II reaction. Remember that these reactions are the body’s attempt to detoxify an intruding chemical. In some cases, the chemical intermediate is a highly toxic compound that will start to destroy cells and tissue. In other cases, the cells are hindered in accepting oxygen and nutrients, or in releasing carbon dioxide along with bound receptor sites. The intermediates may have synergistic, additive, potentiative, or antagonistic qualities. At what level does the chemical in question harm us? Does the chemical become enhanced, or does it cancel out the effects of toxicity? These chain reactions or the exposure of numerous chemicals can be described in the following terms: • Synergistic: The combined effects are more severe than those of the individual chemicals. In this case you may have a chemical that by itself is moderately toxic, but in combination with another has enhanced toxic qualities (i.e., if 1 + 1 = 3). • Antagonistic: The combined effects cancel each other, decreasing the toxic event. One of the chemicals is acting to decrease the effects of the other chemical (i.e., if 1 + 1 = 0.5). • Additive: Some chemicals that are different in chemical structure, shape, and polarity may have the same physiological response in the organism. Thus the effect is a twofold (or more) enhancement (i.e., if 1 + 1 = 2). • Potentiative: A chemically inactive species acts on another chemical, which enhances the chemically active substance (i.e., if 1 + 0 = 2). Most antidotal treatment is based on the organism’s ability to excrete the end product. There are a limited number of antidotes as compared to the vast variety of chemicals that pose exposure hazards. Antidotes are not typically discussed but need to be mentioned because of the dangers associated with their use. Chelating agents are often used as antidotes. Chelating agents form a chemical complex between the insulting chemical and the agent. Either another chemical is introduced to eliminate the newly formed complex or the chelating agent and the insulting chemical combination is eliminated. With these particular agents, the attachment of the antidote to the toxic chemical is how the chemical is removed from the body, thus making it water soluble (in the Phase I and Phase II reactions). For the most part, these reactions occur at the enzyme, or protein, level. The alteration of the metabolism of these chemicals

(enzymes) interrupts the body’s ability to recognize particular unwanted chemicals. If this cycle of reactions continues (repeated exposure), the body is unable to return to the pre-exposure state. If the exposure to the chemical is minimal, specific enzymes in the body that are needed to recognize the unwanted chemical act on the toxic metabolite. The chemical reactions continue to take place until the unwanted substance is excreted from the body.

Testing for Exposure Effects The numbers used for toxic levels are not absolute numbers. There is a misconception in the emergency field that these numbers will tell you the level that is safe and the level that may be dangerous. This is a false assumption. Predictable outcomes when dealing with the toxic levels of chemicals are based in the testing procedure. Although these tests show a level of possible insult, they do not truly identify at what level this insult will take place. Some of this inaccuracy is due to the limited knowledge of biological processes and some lies in the testing procedures.

Acute Exposure The term acute is used to describe a sudden onset or exclusive episode. It relates to a hazardous materials exposure as a single event that causes an injury. This single exposure is usually of short duration and is sometimes classified as nonpredictable. It can occur within a 24-hour period or can be a constant exposure for 24 hours or less. In certain cases, it could also be multiple exposures within the 24-hour time frame. Standard testing routines exist for determining exposure effects. The first step in the procedure usually is to reference all of the information that is currently known about a chemical. The testing technique is then based on the historical reference of the material. Oral toxicity tests are relatively easy to conduct. Groups of rats or mice are used to study the chemical or drug in question (after the reference literature has been searched). These tests are done initially to rate the chemical as to the toxic levels. In other words, the test animals are given increasing amounts of the chemical until an LD is attained. The test animals are divided into four, five, or six groups. In group one, the rats or mice are given a specific amount of the chemical that may or may not be at the TLV. It is, in general, a no-death dose; all the animals are expected to live. However, there may be an observable toxicity event. The remaining groups (depending on the chemical and the testing technique) are given increasing dosages. The last group is given a dose that is known to be completely lethal. From this observation a further sub-ranking of the chemical is done, and for the next 14 days, the death rate, sickness, fur loss, and so on, are observed. The dose that produces a 50 percent death toll over 14 days is referred to as the LD50. Each test group will produce a statistical picture of the chemical dose versus the death rate, fur loss, sickness, and so on. This data is compared to effective doses that are known for the chemical

Chapter 2 Properties and Toxicology

or like chemicals. Both graphs are statistically smoothed into a straight line called the dose response curve. Through statistical modeling, the effective dose and the LD are calculated and the published LD50 is established. Both oral toxicity and inhalation toxicity are measured in this way. The oral toxicity levels are usually for a one-time dose. For cases in which the inhalation exposure is an exposure that occurs for 1 hour to each test group, each test group receives the appropriate dose. In each case the groups of animals are observed for a period of 14 days. At the end of the 14-day cycle, the 50 percent death rate must be observed. If the percentage is higher or lower, the doses are reevaluated until the end result is 50 percent. Because its skin closely resembles that of a human being, a pig is usually used for dermal testing, but rats and mice are also used. The animal is exposed for a period of 24 hours on the bare skin (if hair is present, it is shaven off). Only 10 percent of the total body surface area is used. Observed reactions are matched with the known level of the tested chemical or chemical family. If a chemical needs to be studied further or the results are such that the human element needs to be established, then the procedure is repeated utilizing different species. In general during the testing process, if all the test animal species respond in a similar manner and the statistical slope of the dose response curve is steep, then the results are considered to be accurate for LD50 or LC50. Conversely, if the testing battery showed that there was a diversity of slopes across the animal species spectra and shallow slopes were observed statistically, then the accuracy of the outcome is questioned. The problem is that the numbers emergency responders use are some point in time in which a toxic dose was received. Not only does it give us a small window into the dose response, but it does not tell us the angle of the testing slope. Was the slope steep and thus a good correlation to the human event, or was it a shallow slope, which does not tell us the true toxicity of the chemical in man?

ALERT Inhalation hazards are identified in the Emergency Response Guide Book as A, B, C, and D. These are arbitrary representations of toxicity, as represented: A: LC50 ≤200 ppm B: LC50 >200 ≤1000 ppm C: LC50 >1000 ≤3000 ppm D: LC50 >3000 ≤5000 ppm

Lethal concentration or dose tests are not performed on humans. If the reference literature states a level that caused death in man, this information was obtained through an autopsy performed on the victim of a suicide, homicide, or accidental release. It is hypothesized that the variation of exposure will give the true toxic picture. In simpler terms, without the documentation of a human experience, if the chemical in question has

Table 2-3

Hodge and Sterner Table of Toxicity

Reference

Nomenclature

ppm

LC50 Reference (mg/m3)

10 drops of v­ apor in 1000 ft3

Extremely toxic*

1–10

3–30

Highly toxic

10–100

Moderately toxic*

100–1000

Slightly toxic

1000–10,000

Practically nontoxic*

10,000–100,000

Relatively harmless

Greater than 100,000

¼ cup of ­vapor in 1000 ft3 1 quart of ­vapor in 1000 ft3

43

300–3000

30,000–300,000

Note: These descriptions of toxic levels are relative terms used to convey a scale of toxicity. The specific language does not imply that there are no harmful effects. The values are based on a 4-hour exposure. *These terms are frequently used on an Safety Data Sheets.

been demonstrated to be toxic to most all plant and animal life, then it is considered to be a health hazard to humans. The LD subscripts are maintained as close to 50 as possible. These numbers represent the population that showed a response, and, in most cases, the response is the death rate of the population. The actual number as it moves toward zero represents a more lethal toxic value. In other words, low numbers as toxic values are extremely dangerous chemicals. However, consider a low toxic value and a high number subscript, and the lethality of this particular chemical is very dangerous. In general, the smaller the number that the LC or LD projects, the more toxic the chemical Table 2-3 . In addition, most chemicals are weight dependent. In other words, the greater the mass of the animal or person in relation to the chemical exposure, the higher the likelihood of successfully combating the exposure. Looking at, say, the LD50 of a chemical in order to estimate the LD, you could take the weight of the person and multiply it by the quantity of the material. For example, for a small child weighing 40 lb (18.18 kg), the LD50 would be multiplied by 18.18 kg. So if this child ingested sevin (a moderately toxic pesticide with an LD50 of 500 mg/kg), you would multiply 18.18 kg by 500 mg/kg and obtain 9090 mg (9.090 grams or 0.02 lb). If your patient were a 220-lb man, for example, it would take a little over a tenth of a pound to reach the LD50 (220/2.2 = 100 kg; 100 × 500 = 50,000 mg or 50 grams, which is 0.11 lb). Metabolism, sensitivity, humidity, temperature, and vapor pressure are but a few of the influencing factors not considered here. This calculation is based only on body weight as it relates to the LD50 of the chemical. Because most chemicals are in the solid or liquid state and do not change states of matter, there are more dose problems

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Hazardous Materials Chemistry, Third Edition

than there are concentration problems. Very few become a vapor problem, unless you are experiencing flame impingement on a product or it has been aerosolized (as with chemical warfare agents). There are relatively few chemicals that are airborne contaminants. However, this brings up yet another problem: The testing procedures under which these chemicals are studied do not mimic the conditions an emergency responder may be exposed to. Emergency responders have to deal with the health, flammability, and reactivity issues that chemicals may possess. Under fire conditions, for example, how will a chemical react? What are its synergistic, additive, antagonistic, or potentiative reactions? The problems of how the chemical may react, combust, or jeopardize your health integrity are all significant management problems. Lethal concentrations and doses (including TLVs, PELs, and RELs) are only estimates of the potential health problems that may exist. They are by no means all-or-none limits. That is, they should not be understood as set limits above which health hazards exist and below which no health effects will occur. In looking at gases and vapors, Dalton’s law of partial pressures gives us a valuable tool for establishing the total partial pressure when there is a mixture of gases in an enclosed space. OSHA and EPA have used this basic concept to calculate the toxicity concentrations of mixtures: Ec = Cn/Ln where Ec is the exposure concentration, n represents the number of gases, Cn is the on-scene actual concentration (ppm), and Ln is the reported exposure limit value (ppm). Thus, for three gases you would have: Ec = C1/L1 + C2/L2 + C3/L3

The exposure is given a period of 90 days. At the end of 90 days, all the animals are autopsied for any histological evidence of effect, which is the chemical’s effect as compared with the control group(s).

Chronic Exposure When an exposure occurs during 80 percent of the total life span of an organism, it is called chronic exposure. Chronic, or long-term, effects are much harder to establish than acute effects because there are so many more confounding factors. Acute exposure and the organism’s sensitivity are limits to the testing procedure. Our understanding of toxicological responses and knowledge of biochemistry is limited. Chronic exposure can also influence some, any, or all offspring. Accumulation, or acclamation, may lead to hyposensitivity or hypersensitivity. As in the acute testing process, a certain degree of inaccuracy is also seen in the chronic exposure figures. Most of what is seen and read about is from an after-the-fact chronic event. In other words, someone or a group of individuals has become ill or has died from an exposure. An immediate and obvious cause and effect will not be obvious with all chemical exposures.

ALERT Exposure level numbers should not be considered as safe ­levels, but rather as a statistical analysis of risk that may result in injury from an exposure. They provide an expedient method for ­estimating a chemical’s potential toxic effects.

or, in general: Ec = C1/L1 + C2/L2 + . . . + Cn/Ln

Subchronic Exposure Subchronic and subacute are two terms that are sometimes used interchangeably to describe the same type of exposure. However, the appropriate term is subchronic. This type of exposure is an acute exposure that is repetitive. It is a recurring event. It is an exposure that happens during approximately 10 percent of the organism’s total life span. The testing procedures for subchronic exposures are based on the LD50 or LC50, which established death in 50 percent of the test group. The testing procedure is carried out in a minimum of two species, with each having a control group. Three to four groups are tested in a similar manner. At the top end, a dose under the LD or LC and high enough to show signs of injury, but not death, is given. At the low end of the dose range, the treatment is such that there should not be any noticeable effects. Depending on the test chemical, a middle point is chosen. If the curve from the acute testing is shallow, then the two or more middle points are picked. If the curve is steep, one point is selected.

As a starting point, the chronic toxicity of most chemicals is determined through oral acute studies. There is good reason for this particular starting point. The first studies of chronic toxicity were undertaken to isolate those chemicals that could potentially become a problem if introduced into food, such as preservatives and production additives. This method of exposure study is easy to do. Chronic exposure studies have been expanded in recent years to include chronic inhalation and topical exposures. Similar to the evaluation of subchronic (subacute) exposures, the chronic-exposure experiment starts out by finding the toxicity range of the chemical in question. Most of the information is gathered from the acute studies. The chemical is introduced into the animal by placing it in food. This process lasts for 90 days, during which time a variety of dose ranges are used to establish the high, medium, and low toxic ranges. In the high toxic range, the effect is limited. In the low toxic range, no undesirable effect is noted. In the moderate range, the effect is mild. In addition to these three groups under study, there is a control group.

Chapter 2 Properties and Toxicology

Typically, a large number of animals and two or more species are used. The oral ingestion is started from birth and continues through approximately 80 percent of the animal’s life expectancy. Every day the animals are observed for negative effects, and a battery of tests is performed weekly. At the end of the experiment, all animals are autopsied and histological tests are

45

analyzed. From the data, a statistical model is used to give the dose effect response. This type of testing can become extremely expensive. It can take years to observe some effect. If, for example, new factors (testing processes) were introduced in the experiment during the testing period, the results would be skewed.

Case Study Answers 1. What has happened? Methanol has a flammable vapor that is heavier than air and that moves very fast within the environment to find an ignition source. Its flash point is extremely low, which means that when given a source of ignition, it will catch fire; when in a bulk supply, it will back flash to the chemical source given the opportunity.

2. What will or could happen? These incidents show that a complete and through investigation, identification, and research of the chemicals must be made prior to any educational demonstration. Whenever an experiment for educational use is performed, a site safety plan must be made. It is through this site safety plan that the hazards are identified and the safety protocols are established. If during this process it is shown that the safety of spectators is at risk, then these “experiments” should remain in the lab under strict safety conditions and filmed for observation rather than be performed for a live audience.

improvement store, drug store, auto repair shop, and the list continues. Within the educational arena, some individuals do not think through the problem, hence the need for site safety plans. Safety plans are sometimes thought of as just another task, when in fact they are, and should be thought of as, a necessary part of a process. This process identifies the issues that may pose a threat to the students. The planning process is a process of fact discovery. What can be taken away from this incident is that even when superficially the situation may seem safe, consider the chemical and physical properties of the chemical(s) with which you are engaging. Look at these basic principles to guide you toward the safety precautions. Remember, all chemicals have chemical and physical properties. It is understanding the actions and reactions of the chemicals that is important. These are not just definitions in books but principles of nature, and negative outcomes can and have resulted with inappropriate handling of chemicals. The key here is to apply your understanding of these properties to the environment you have and look at these principles as your guide toward your strategies.

3. What can you change? In general, society has become complacent when it comes to chemicals. Chemicals are in the grocery store, the home

Design credits: RedFlames: Drx/Dreamstime.com; Steel texture: © Sharpshot/Dreamstime.com; Orange flames: © Jag_cz/Shutterstock, Inc.; Stacked photo background: © Vitaly Korovin/Shutterstock, Inc.; Paper: © silver-john/Shutterstock, Inc.; Application Tip: © iraua/Shutterstock, Inc.; Alert: © iraua/Shutterstock, Inc.; Technical Note: © Eky Studio/Shutterstock, Inc.

WRAP-UP In Summary • When educating individuals on hazardous materials, basic principles of chemistry should be considered as more than just definitions. • Physical and chemical properties describe the fundamental behaviors of chemicals and how they interact within the environment.

• Through an understanding of the guiding chemical principles, the responder will be able to value each piece of information as it becomes available. • It this through the understanding of these principles and their association with chemical families that you can now anticipate what can happen during a hazardous materials incident.

Key Terms absorption  Commonly refers to dermal contact, but it can occur in any organ. acid  A material that donates hydrogen ions (H+) when dissolved in water yielding more H3O+. acute exposure  Refers to a sudden onset of symptoms or an exclusively short-term episode. additive  Some chemicals that are different in chemical structure, shape, and polarity may have the same physiological response in the organism. Thus the effect is a twofold (or more) enhancement (kind of like if 1 + 1 = 2). antagonistic  The combined effects cancel each other, decreasing the toxic event. One of the chemicals is acting to decrease the effects of the other chemical (kind of like if 1 + 1 = 0.5). appearance  The form, size, and color of a material. base  A substance that accepts hydrogen ion (H+) ions when dissolved in water yielding more hydroxide (OH-). boiling point  The temperature at which the atmospheric pressure and the vapor pressure of a liquid are equal so the substance changes from a liquid to a gas or vapor. chemical properties  Describes a substance’s reactivity. chronic exposure  A long-term exposure, usually recurring during 80 percent of the total life span of the organism. condensation  The conversion of a gas (or vapor) into the liquid state. conduction  The mechanism by which heat is transferred between materials in contact with one another. convection  The mechanism of heat transference by the movement of a gas or liquid. density  The mass of a substance per unit volume; a relationship and can be applied to all three states of matter. dose response  Describes the change or effect caused by a substance on an organism by issuing defined levels of exposure. dusts  Fine particles of solid matter such as coal dust, saw dust, and grain dust. expansion ratios  The ratios of compressed gas or liquefied gas volume in the container to what the true gas volumes would be outside the container.

flammable ranges or limits  Represents the minimum and maximum concentration of a chemical in the air that is favorable for ignition to occur; sometimes referred to as explosive limits. flash point  The minimum temperature under which a liquid will give off vapors to form an ignitable mixture in air, provided that the flammable limits are within favorable perimeters and that an ignition source is present. freezing point  The temperature at which the product is going from the liquid phase into a solid phase. gas  A state of matter with no definite volume or shape. heterogeneous  Matter existing as a mixture of pure substances having different chemical and physical properties throughout the sample. homogeneous  Matter existing as a mixture of pure substances having the same chemical and physical properties throughout the sample. ignition temperature  The minimum temperature at which a material will ignite and sustain combustion without a continuing outside source of ignition. The heat of combustion relates to a reaction in which the products are completely oxidized or in which complete combustion takes place. ingestion  The intake of a solid or liquid into the gastrointestinal tract. inhalation  The intake and absorption of a gas (fume, aerosol, particle, dust, and so forth) into the lungs. inhalation injuries  Injuries that include absorption across the alveolar membrane through or into the bloodstream. injection  The forced introduction of a substance into the body. lower explosive limit (LEL)  The minimum concentration bounds when describing flammable range. melting point  The temperature at which a material changes from a solid to a liquid. miscibility  The ability of materials to dissolve into a uniform mixture at all ratios. mists  Liquids that have been atomized; for example, spray paint, high-pressure oil leaks, and aerosolization of nerve agents.

Chapter 2 Properties and Toxicology

outage  A potential to breach the container under high temperature conditions. particle size  Used for describing dimensions of: solid particles (flecks, powders, dust), liquid particles (droplets, mist, aerosolized liquids), liquid vapors (fumes), or gaseous particles (bubbles, fumes). persistence  The tendency of a material to remain in the environment for a long period of time. pH (positive hydronium ion)  The scale used to measure how acidic or basic a solution is; -log[H3O+]. physical properties  Describes the look and feel of a chemical and not its reactivity. potentiative  A chemically inactive species acts on another chemical, which enhances the chemically active substance (kind of like if 1 + 0 = 2). radiation  The outward movement of heat from a source via electromagnetic waves; the mechanism by which heat is transferred between two objects that are not touching but are in relatively close proximity to one another. solubility  The ability of a material to blend uniformly with another material to form a solution. solute  The component or components of lesser abundance in a solution; a material dissolved in another as a component of the solution. solvent  The most abundant component of a solution; a material in which another material is placed and dissolves to form a complete solution.

specific gravity (SG)  The weight of a solid or liquid compared to an equal volume of water. subchronic exposure  Recurring acute exposure that, in total, happens during approximately 10 percent of the organism’s life span. sublimation  The process when a material goes directly to the vapor state from the solid phase without going through the liquid state. synergistic  The combined effects are more severe than those of the individual chemicals; a chemical that by itself is moderately toxic, but in combination with another has enhanced toxic qualities (kind of like if 1 + 1 = 3). thermal conductivity  A measure of the amount of electric current a material can carry; this principle is used in thermal conductivity. upper explosive limit (UEL)  The maximum concentration bounds when describing flammable range. vapor density (VD)  A comparison like specific gravity, but of a gas or vapor to the ambient air. vapor pressure (VP)  The pressure that is exerted by a vapor on its liquid when in equilibrium with it; also, the pressure exerted by a vapor against the sides of an enclosed container. vapors  The gases that are given off from flammable or volatile liquids. viscosity  A measure of resistance to flow; describes the thickness of liquids or how well they flow.

Review Questions 1. Density is defined best by which statement? a. How hard a substance is b. How much of a substance there is c. The volume per unit mass (volume/mass) d. The mass per unit volume of the substance (mass/ volume)

4. If you could measure a gas released into the environment as it is traveling through the air, you would see three distinct areas of concentration. What are these areas called? a. Flammable ranges b. Explosive limits c. Flammable limits d. All the above

2. What is a comparison of weight between water and the material being tested called? a. Specific density b. Density c. Specific gravity d. Vapor density

5. Match the following abbreviations of specific toxicological values with their definitions: a. PEL b. MAK c. TLV d. EL e. WEEL

3. What is the minimum temperature under which a liquid will give off vapors to form an ignitable mixture in air without sustained combustion called? a. Vapor pressure b. Fire point c. Ignition temperature d. Flash point

6. a. exclusion limit b. workplace environment exposure limit c. maximum allowable concentration d. threshold limit value e. permissible exposure limit

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WRAP-UP 7. Match the following definitions to the appropriate toxicological term. a. Based on an 8-hour day, 5 days a week, to give a 40-hour workweek. b. The letter “s” identifies that the material is absorbed through the skin. c. Only occurs for 15 minutes and is not repeated more than four times a day. Each 15-minute exposure event is interrupted by a 60-minute nonexposure environment. d. Immediately dangerous to life and health. e. The letter “c” denotes ceiling levels. 1. STEL 2. TLV-TWA 3. IDLH 4. TLV-c 5. TLV-s

c. d. e. f. g.

8. Match the following: a. LClo b. LDlo

Problem Set Answers Problem Set 2-1 1. The property that describes the force exerted on by a vapor on its liquid when in equilibrium with it or the force exerted on the sides of the enclosed container is:

b. vapor pressure.

2. A substance that has a predominate positive end and predominate negative end is said to be:

c. a polar substance.

3. The liquefied gas volume that is within a container as compared to the gas volume outside the container is called:

c. expansion ratios.

LC50 LD50 LCT50 MAC RD50 1. The lowest concentration of airborne contaminates that can cause injury. 2. Fifty percent of the test population died from the introduction of this airborne contaminate. 3. A statistically derived LC50 (LDT50 statistically derived lethal dose). 4. A 50 percent calculated concentration of respiratory depression in response to an irritant over a 10- to 15-minute time frame. 5. The lowest dose (solid or liquid) that can cause an injury. 6. The maximum allowable concentration (European). 7. Fifty percent of the tested population died from the introduction of this chemical, which may be a solid or liquid.

4. The solute:

b. is the material in lesser amount.

Problem Set 2-2 1. The flammable ranges:

c. represent both the maximum and minimum concentrations within an environment.

2. Which is the minimum temperature at which a material will ignite and sustain combustion? b. Ignition temperature 3. What is the mechanism by which heat is transferred between materials? c. Conduction

Chapter 2 Properties and Toxicology

4. What do we call the point at which we have a minimum ratio of flammable gas/vapor to air? a. LEL Problem Set 2-3 1. List four considerations as they pertain to an exposure. d. Concentration, absorption, detoxification, excretion 2. List the modes of exposure. a. Absorption, inhalation, ingestion, injection

3. Acute exposure refers to: c. an exposure lasting 24 hours or less. 4. Which of the following numbers would be used in an emergency response?

d. All the above

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CHAPTER © Sergey Nivens/Shutterstock, Inc.

3

The Atom LEARNING OBJECTIVES Upon completion of this chapter, you should be able to: • Describe how to use the periodic chart to predict scene outcomes given a set of chemicals. • Describe atomic structure and the atom’s components. • Use the periodic table to predict the electronic structure of an element and predict reactivity. • Compare the relationship between the neutral atom and ions. • Compare the groups, periods, regions, and families on the periodic table. • Integrate the relationship between the group’s number at the top of the periodic table and the electronic structure of the atom. • Categorize the trends on the periodic table. • Examine the formation of anions and cations. • List the three hazards of radiation. • Identify the forms of measurement for radiation.

NFPA Citations and Competencies Citation or Competency Heading

NFPA 472 Reference

Hazard evaluation

11.3.3.3(3)(d), A.3.3.49, A.7.1.2.2(3)(5), A.8.1.2.2(2)(d)(5), A.9.3.1.2.2(2)(e), A.11.3.3(3)

Radiological

5.2.1.6.5, 6.2.3.1(3)(b), 6.11.2.2(1)(d), 7.3.2.2(2), 8.2.2(6)(f), 18.4.1, 20.4.1(5), 23.3.1 (3), 24.2.1(5), a.3.3.68, A.3.3.68.1, A.5.2.3(7), D.1.1.1, D.1.1.2

Hazard and response information

4.4.1(4), 5.1.2.2(b), 5.2.2, 5.2.3, 7.1.2.2(1)(b), 7.2.2, 7.2.2.1, 7.2.2.4, 7.2.2.5, 8.1.2.2, 8.2.1, 9.2.3.1, 9.3.3.1, 9.4.1.2.2(b), 11.1.2.2, 11.2.1, 11.5.2, A.4.2.3, A.4.4.1(4),.2.1

Decontamination

5.1.2.2, 5.3.4, 5,4,1, 6.1.1.1, 6.2.1.1.1, 6.2.1.2, 7.3.3, 7.4.4

Response options

5.1.2.2, 6.5.1.2.2, 6.9.3.1, 6.9.4.1, 6.10.1.2.2, 6.10.3.3, 6.11.1.2.2, 6.11.3.2, 7.1.2.2, 7.2.5.2, 7.2.5.7, 7.3.1.1, 7.5.1, 8.1.2.2, 8.3.2, 8.5.1, 9.2.1.2.2

Disposal

5.2.2, 6.4.3.1, 7.3.3, 8.3.4.5.4, 9.3.1.2.2, 9.3.3.3, 10.4.1, A.3.3.16.4

Termination considerations

A.3.3.66, E.2.5

Risk assessment

21.1, 21.2.1, 21.2.2

Case Study April 26, 1986, and March 11, 2011, mark the two dates on which the only two Level 7 nuclear incidents have occurred. The first was at Chernobyl in Ukraine, and the second was in Fukushima, Japan. Each presented responders with a myriad of issues. In 1990, the International Atomic Energy Agency (IAEA) defined nuclear accidents in terms of event magnitude. Similar to the logarithmic scale of earthquakes, the nuclear event scale Courtesy of Bill Hand. is an attempt to quantify the level of health and environmental effects, which requires a very specific degree of planning and countermeasure approaches at all levels of response. These events, from worst case to no safety significance, are: Level 7: Major accident Level 6: Serious accident Level 5: Accident with wide consequences Level 4: Accident with local consequences Level 3: Serious incident Level 2: Incident Level 1: Anomaly incident Level 0: Deviation Levels are thought of as three general areas of intensity. Level 0 has no true safety significance to a local community, but may have some relative significance to the plant’s operation. Levels 1–3 are incidents with impact that is perhaps significant to the local area. This is defined as having limited health and safety consequences and limited environmental impact. Levels 4–7 come with significant human, community, county, and continent impact with associated global concerns. Figure 3-1 is a representation of all nuclear power plants in the United States. Looking at the map, identify the areas in which a Level 3 versus a Level 7 incident could affect a region. Ask yourself what planning resources would you have for such an event, considering the evacuation zone around the event in Fukushima, Japan was 30 km or 18 miles. On September 13, 1987, in Goiânia, Brazil, a section of the city was contaminated with cesium-137 (from radioactive cesium chloride). The source was purchased in 1977 by a privately owned radiotherapy institute. Over the next decade, the institute experienced a decline in business and moved to a different location. It also engaged in disputes with business partners (this incident has many political, legal, and business relationship implications). The radiological contamination within the city was extensive due to the hospital leaving the original location and abandoning the radiological isotopes there. “Salvagers” going into abandoned buildings was commonplace at that time. On September 13, 1987, the guard hired to monitor the premises did not show up for work and no replacement officer was assigned to the location. During the day, the premises were entered by persons looking for “salvageable” materials. The capsule that contained the cesium chloride was removed and taken to a salvage company by one of the salvage people who entered the building. Cesium-137 has a half-life of 30 years. Originally purchased with an activity level of 74 terabecquerels (TBq), it was estimated that its activity at the time of “salvage” was in the neighborhood of 50 TBq (approximately 44 TBq has since been recovered during the clean-up of this incident; for a detailed report, see http://www-pub.iaea.org/mtcd/publications/pdf/pub815_web.pdf). At some point, the capsule containing the cesium-137 was taken to the home of the salvager. Once taken home, the capsule was eventually ­damaged, revealing a small opening that contained the cesium chloride and exposing the handler to the source. The substance glowed bright blue. Thinking that the material was worth money, he brought it into the house and invited friends and family to witness this “glowing material” that he found. That evening his wife became nauseated and started to vomit. Her condition worsened over the next several days. On September 24, the brother of the original salvage operator scraped some of the material out of the capsule and painted the concrete floor and his daughter’s skin with the “glowing” material. The child was eating at the time and it is believed that she ingested some of this material. On September 28, it was noticed that persons who had any contact with this capsule and/or its contents were growing increasing ill. The capsule was packaged and taken to the local medical facility in a plastic bag, and the situation of the capsule’s origin was described. By September 29, a medical student used a Geiger counter to confirm his suspicions and found dangerously high levels of radiation around that section of the city. Using the principles set forth in this section, answer the following questions: 1. 2. 3. 4.

What has happened? What can you do to change the outcome? What level of radiation should you be concerned with? What event level is this?

Figure 3-1  Nuclear power plants in the United States.

Content removed due to copyright restrictions

52 Hazardous Materials Chemistry, Third Edition

Chapter 3 The Atom

Introduction The structure of the atom is remarkable. Greek philosophers imagined the concept of atoms based upon logic and intuition, but it was not until recent history that experimental evidence supported what philosophers imagined. Antoine Lavoisier in 1777 established the idea of combustion, and it was the first time that scientific experiments gave rise to the empirical data. From these early days of the scientific method, measurements of chemical reactions were conducted. The interesting fact of this brief story is the fact that early scientists “saw” that there were building blocks in the material world, that these building blocks have a system, that the elements on the periodic chart have a repetition of properties—and that there was a way to organize the known elements so that in some cases, predictions of how an element will react can be made. It is this predictable understanding of the atoms that you are going to investigate. This will then allow you to predict physical properties of materials.

The Structure of Atoms In 400 bc, a Greek philosopher by the name of Democritus was the first to describe a system of matter consisting of basic building blocks, which are known today as the elements. However, it was not until the Middle Ages that people attempted to produce gold from common metals by means of chemical experiments. This primitive science was called alchemy, and it was the forerunner of chemistry. Alchemists, although driven by the desire to manipulate matter, were the first to acquire a wealth of knowledge through observation. Thousands of years would pass before the investigation of the properties of the elements would show that they are built of atoms, which consist of even smaller particles called protons, neutrons, and electrons Figure 3-2 . Atoms have been found

ATOM Nucleus (protons and neutrons)

Electron cloud

NUCLEUS Proton Neutron

Figure 3-2  A graphic representation of an atom. © Jones & Bartlett Learning.

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to contain a nucleus, which accounts for most of the mass of the atom. This nucleus contains the protons and the neutrons, with the electrons found around it. The important properties of the subatomic particles are their mass and their electrical charge. Electrons carry a negative charge to balance the positive charge of the protons in the nucleus. The positively charged particles are called protons, and the uncharged particles in the nucleus are called neutrons. Protons and neutrons both have an approximate mass of 1 on the atomic mass scale, while electrons are considered to have essentially zero mass (1/1840 is the mass as compared to the proton). The sharing or transfer of electrons is the basis of chemical reactions and the bonding of elements.

Technical Note During radioactive decay, the particle that is identified as the alpha particle consists of two protons and two neutrons (helium nucleus). The beta particle is identified as the electron, and gamma is the energy liberated from the decay.

In some chemistry books, the atomic number is identified as the “Z” number and the “A” number indicates the mass number. This designation comes up in connection with radioactive isotopes. Atoms of different elements vary in the number of their protons, neutrons, and electrons. The factor that determines the type of atom is the number of protons in the nucleus. The number of neutrons may differ depending on the isotope of the atom. All electrically neutral atoms contain an equal number of protons in relation to the number of electrons. The number of protons dictates the number of electrons within a neutral atom. If the atom has 14 protons, then there will be 14 electrons in the atom when neutral. The number of protons determines the atomic number (“Z” number). The atomic number correlates to the order of the elements on the periodic table (see the inside back cover). All atoms except those of the most abundant form of ­hydrogen contain some neutrons in the nucleus. The neutrons do not affect the conventional chemical properties of the atom but significantly affect its mass. Because the electrons are so light, most of the mass of an atom results from the number of neutrons and protons. The mass number (“A” number) of a particular isotope is the sum of the protons and neutrons of that atom. Number of Protons + Number of Neutrons = Mass Number (A) Atomic Number (Z) = Number of Protons = ­ Number of Electrons in a neutral atom Many elements contain two or more slightly different types of atoms called isotopes. Isotopes are two or more forms of an element that have the same number of protons (and electrons) but differ by the number of neutrons. They may be defined as

54

Hazardous Materials Chemistry, Third Edition

atoms with the same atomic number but with different numbers of neutrons, and therefore with different mass numbers (“A”). Isotopes of the same element have identical conventional chemical properties. Most elements that exist in nature have one predominant isotope; however, some of the elements contain several isotopes of relatively high abundance. There are 92 naturally occurring elements; the rest are man-made. After uranium (Z = 92), the majority of the rest are observed only in the laboratory. When describing atomic weight, you are dealing with all the isotopes that naturally occur for that element and the value reported in a weighted average of all the isotopes. That is, if the element exists in the form of two or more isotopes, then the atomic weight will be an average of the masses of each isotope and the percentage of occurrence. For example, hydrogen normally does not have a neutron in the nucleus but can have one or two neutrons in its respective isotopes. Therefore, hydrogen is said to have three isotopes Figure 3-3 .

P

P N

P N N

Hydrogen

Deuterium

Tritium

Figure 3-3  The atomic weight of hydrogen is 1.008, which accounts for its three isotopes. © Jones & Bartlett Learning.

The Periodic Table In 1869, Dimitri Mendeleev discovered that elements could be organized in a logical manner based on their properties. His observations allowed him to predict elements that were not yet discovered at the time. In his original chart, Mendeleev based the known elements in groups and periods based on what was known in his day. He left gaps, assuming that other elements not yet discovered would complete the table. His system of classification gave us the periodic table. There are very detailed periodic tables and others that contain less information. At a minimum, every periodic table will contain the following information on each element Figure 3-4 : • The atomic symbol. The atomic symbol consists of one or two letters. The first letter is always capitalized. If there is a second letter, it will be lower case. • The atomic number. Recall the atomic number represents the number of protons in the nucleus. • The atomic mass. This number, which usually contains a decimal point, represents the weighted average of the masses of all isotopes of that element. Chemists use a counting unit known as the mole. A mole is equal to 6.022 × 1023 items. The units for atomic mass can be either the atomic mass unit (amu) or grams per mole (g/mol). The

Figure 3-4  Information for an element found on any periodic table. © nmcandre/Getty Images.

atomic mass is the mass, in grams, of 6.022 × 1023 atoms of that element. The unit g/mol is the more useful unit to use with the atomic masses found on the periodic table. A chemist will use the term amu when referring to a single unit only. More commonly, chemists deal with actual, measurable amounts of chemical in the real world.

Families and Groups The periodic table provides a general framework of the ­elements to show relationships between the chemical groups Figure 3-5 . This table arranges the chemicals according to atomic number. Looking at the chart, you see elements arranged in vertical columns called groups. Within each group, elements that have similar chemical properties are found. Although hydrogen is in the same column as the alkali metals, it is considered a nonmetal under most conditions, thus the line that separates metals from nonmetals may start under hydrogen on some periodic tables. Each horizontal row is called a period. Atoms tend to become smaller going from left to right within a row of the periodic table. This is because of the more positive nuclear charge going across a row. Periods end with a noble gas. The rare earth metals (or inner transition metals) are placed in rows 6 and 7. For easy reading, these elements are pulled to the lower portion of the table. Within each box, the elements (atoms that represent elements) are represented by symbols. It is these symbols that are used to write formulas to represent compounds There is a line that separates the metals from the nonmetals on many periodic tables. It usually starts below boron and is shaped like a staircase. Elements to the left of the line are metals. Elements to the right of the line are nonmetals. You can further identify areas that represent certain qualities of chemicals by placing them into regions. The first two columns or groups (groups 1 and 2) and the seven metal elements in groups 13 and 14 (IIIA–IVA) are termed the

7

6

5

4

3

2

1

lanthanum 57

La

barium 56

cesium 55

Y

actinium 89

Ac

radium 88

Ra

(226)

francium 87

Fr

(223)

(261)

Rf

rutherfordium 104

178.49

Hf

hafnium 72

91.22

Zr

zirconium 40

47.88

Ti

titanium 22

4 IVB

5 VB

U

Pa (231)

Th 232.04

238.03

Figure 3-5  The periodic table.

*Note: For radioactive elements, the mass number of an important isotope is shown in parenthesis; for thorium and uranium, the atomic mass of the naturally occurring radioisotopes is given.

Actinide Series

uranium 92

protactinium 91

thorium 90

Nd 144.24

Pr 140.91

Ce 140.12

neodymium 60

praseodymium 59

cerium 58

(262)

Bh

bohrium 107

186.21

Re

rhenium 75

(99)

Tc

technetium 43

54.94

Mn

manganese 25

(263)

Sg

seaborgium 106

183.85

W

tungsten 74

95.94

Mo

molybdenum 42

52.00

Cr

chromium 24

7 VIIB

(262)

Db

dubnium 105

180.95

Ta

tantalum 73

92.91

Nb

niobium 41

50.94

V

vanadium 23

6 VIB

1.01

*Atomic Mass

Lanthanide Series

(227)

138.91

Ba

137.33

Cs

132.91

88.91

Sr

87.62

85.47

yttrium 39

Rb

strontium 38

rubidium 37

Sc

44.96

calcium 20

potassium 19

Ca

24.31

22.99

40.08

Mg

Na

K

magnesium 12

sodium 11

39.10

scandium 21

9.01

3 IIIB

Be

Li

beryllium 4

lithium 3

H

1

hydrogen

Symbol

Atomic Number

Element

55.85

Fe

iron 26

8 VIII

(237)

Np

neptunium 93

(147)

Pm

promethium 61

(265)

Hs

hassium 108

190.2

Os

osmium 76

101.07

Ru

ruthenium 44

PERIODIC TABLE OF THE ELEMENTS

6.94

2 IIA

1.01

H

hydrogen 1

1 IA

(244)

Pu

plutonium 94

150.36

Sm

samarium 62

(266)

Mt

meitnerium 109

192.22

Ir

iridium 77

102.91

Rh

rhodium 45

58.93

Co

cobalt 27

9 VIII

(243)

Am

americium 95

151.97

Eu

europium 63

(269)

Uun

ununnilium 110

195.08

Pt

platinum 78

106.42

Pd

palladium 46

58.69

Ni

nickel 28

10 VIII

(247)

Cm

curium 96

157.25

Gd

gadolinium 64

(272)

Uuu

unununium 111

196.97

Au

gold 79

107.87

Ag

silver 47

63.55

Cu

copper 29

11 IB

(247)

Bk

berkelium 97

158.93

Tb

terbium 65

(277)

Uub

ununbium 112

200.59

Hg

mercury 80

112.41

Cd

cadmium 48

65.39

Zn

zinc 30

12 IIB

(252)

Es

einsteinium 99

164.93

Ho

holmium 67

(284)

Nonmetals

(257)

Fm

fermium 100

167.26

Er

erbium 68

(288)

Uup

ununbium Ununpentium 115

ununbium Ununquadium 114

Uuq

208.98

Bi

bismuth 83

121.75

Sb

antimony 51

74.92

As

arsenic 33

30.97

P

phosphorus 15

14.01

N

nitrogen 7

15 VA

207.2

Pb

lead 82

118.71

Sn

tin 50

72.61

Ge

germanium 32

28.09

Si

silicon 14

12.01

C

carbon 6

14 IVA

Metalloids

Metals

(251)

Cf

californium 98

162.50

Dy

dysprosium 66

(284)

Uut

Ununtrium 113

204.38

Tl

thallium 81

114.82

In

indium 49

69.72

Ga

gallium 31

26.98

Al

aluminum 13

10.81

B

boron 5

13 IIIA

(258)

Md

mendelevium 101

168.93

Tm

thulium 69

(292)

Uuh

ununbium Ununhexium 116

(209)

Po

polonium 84

127.60

Te

tellurium 52

78.96

Se

selenium 34

32.07

S

sulfur 16

16.00

O

oxygen 8

16 VIA

(259)

No

nobelium 102

173.04

Yb

ytterbium 70

(294)

Uus

ununbium Ununseptium 117

(210)

At

astatine 85

126.90

I

iodine 53

79.90

Br

bromine 35

35.45

Cl

chlorine 17

19.00

F

fluorine 9

17 VIIA

(260)

Lr

lawrencium 103

174.97

Lu

lutetium 71

(294)

Uuo

ununbium Ununoctium 118

(222)

Rn

radon 86

131.29

Xe

xenon 54

83.80

Kr

krypton 36

39.95

Ar

argon 18

20.18

Ne

neon 10

4.00

He

helium 2

18 VIIIA

Chapter 3 The Atom 55

56

Hazardous Materials Chemistry, Third Edition

representative metals. The groups in the lower portion of the main portion of the periodic table are called the transition metals and are identified by the groups 3–12 (IIIB - IIB). Between the nonmetals and the right-side representative metals are the metalloids. These have properties in between metals and nonmetals. Underneath the transition metals and a part of this region are the inner transition metals or rare earth metals. This area has two main groups called the lanthanides and actinides. Lanthanides and actinides occur naturally, but the later portion of the actinides are man-made through neutron bombardment and are extremely rare.

Electronic Structure of the Atom Because almost all of the chemical reactivity of the elements is the result of the behavior of the electrons in an atom, a more thorough understanding of the behavior of electrons within an atom is essential to being able to predict the chemistry of the elements. The work of physicists such as Niels Bohr and Erwin Schrodinger contributed greatly to our understanding of the behavior of electrons within atoms. Chemists think of electrons as occupying orbitals. The pictorial representation of these orbitals have a characteristic size and shape and represent the probable positions of electrons within an atom. Each orbital can represent a maximum of two electrons. As the number of electrons increases within an atom, the number of orbitals that are occupied by electrons also increases. Much of the chemistry of the elements can be explained when you group orbitals of similar energies together into “shells”. These shells can contain more and more orbitals and therefore more and more electrons as they extend farther from the nucleus. For example, the first shell is the smallest and contains only one type of orbital. Because each orbital can contain a maximum of two electrons, the first shell can only hold two electrons. The second shell represents four orbitals. Because each orbital can contain a maximum of two electrons, the second shell can hold a maximum of eight electrons. For all the elements discovered so far in the ground state (not excited by radiation or another form of energy), there are seven shells. The maximum number of electrons each can contain are as follows: 2, 8, 8, 18, 18, 32, 32 Figure 3-6 .

Nucleus 1st shell = 2 electrons 2nd shell = 8 electrons 3rd shell = 8 electrons

Figure 3-6  A model of atomic orbital shells and the number of electrons can be contained in each shell, which aids in understanding the atom and predicting chemical behavior.

As the number of electrons in an atom increases, more shells become occupied. Electrons will occupy these shells in a certain order. For example, an atom of helium contains two electrons. Those two electrons occupy the first shell. An atom of lithium contains three electrons. The first two electrons in a lithium atom will occupy the first shell. Because the first shell is full with two electrons, the third electron will occupy the next shell. An atom of magnesium contains 12 electrons. The first two electrons will occupy the first shell. The next eight electrons will occupy the second shell, and the remaining two will occupy the third shell.

Technical Note You can quickly determine how many electrons are in an atom by looking at the periodic table, since the atomic number represents the number of protons, and the number of protons equals the number of electrons in a neutral atom.

The last, or outermost, shell that electrons occupy in any atom is referred to as the valence shell. In the magnesium atom, three shells are occupied. The third shell containing only two electrons is referred to as the valence shell. The electrons that occupy that valence orbital are referred to as valence electrons. Atoms are particularly stable when the valence shell is completely occupied. For example, helium has two electrons that occupy that first shell. Because the first shell is “full” with two electrons, helium is a very stable element. Helium does not react and samples of helium contain individual stable atoms. You will find this is the case for all the elements known as “noble gases.” The chemistry of the elements can be predicted by the occupancy of electrons in an atom’s valence shell. In the earlier example, you determined that magnesium has 12 electrons, 2 of which occupy its valence shell. Because an atom is most stable when its valence shell is full, magnesium reacts in such a way that those two valence electrons are lost. That is why you will find magnesium in nature as a component of salts, ionic compounds where magnesium carries a charge of +2. The magnesium atom in that compound contains two fewer electrons than protons. There is no need to memorize how many electrons can fit in each of the shells within an atom, for this number can be determined quickly by looking at the periodic table. Take a look at the first row on the periodic table. It contains only hydrogen and helium. That is two elements. The first shell can hold two electrons. The second row of the periodic table contains eight elements. So does the third row. The second and third shells can each hold eight electrons. Go ahead and count across the fourth row of the periodic table. You will find there are 18 elements. The fourth shell holds 18 electrons. This is also true for the fifth row and the fifth shell. If you remember to include the lanthanides and actinides in your element count, you will find that the sixth and seventh rows contain 32 elements. The sixth and seventh shells hold the same number of electrons. This pattern between the periodic table and the maximum number of electrons per shell is not a coincidence, as the behavior of

57

Chapter 3 The Atom

valence electrons is the basis for the behaviors that Mendeleev observed when organizing the elements on the periodic table.

Electronic Relationships Atomic Orbitals The shell model of the atoms can be used to predict the chemistry of many elements, but it has its limitations. For a more thorough understanding of the electronic structure of an atom, it is necessary to describe in better detail the nature of atomic orbitals within each shell. In the late 1800s and early 1900s, our understanding of matter increased significantly with the onset of quantum mechanics. Physicists discovered that radiation not only behaves with wavelike properties, but also could behave like streams of particles. Particles of radiation are now referred to as photons. Soon after wave/particle duality was used to describe radiation, the concept was also applied to electrons as well. It was determined that electrons not only behaved like particles, but also like waves. Like a plucked guitar string, standing waves have a lowest energy frequency and higher energy ones, of shorter wavelength. If an electron were like a standing wave, it would also have a lowest energy frequency and higher energy ones. So the question becomes, how does this wave/particle duality affect the model of the atom? In Bohr’s theory, electrical energy of the atom rotates around the nucleus. In Schrodinger’s model, the electron function looks more like a wave. The earliest model some students may learn of the atom is the Bohr model, with electrons rotating around the center of the atom. This is an easy visualization. With Schrodinger’s model, it can be difficult to visualize and the mathematical approach is very complex; however, the model is important because without it, some early experimental results that studied the nature of matter could not be explained. So let’s start by looking at the behavior of an electron in an atom as a wave. Let’s say there is a string tied down at both ends very much like the string of a guitar. You pluck this string and the string vibrates, but it only vibrates at a very precise frequency. So relating this back to the atom, Schrodinger showed only certain waves are possible for electrons in an atom, which defined the energy of an electron in terms of wave functions Figure 3-7 . 1. Only certain wave functions can be found to be acceptable at certain allowed energy values. 2. The equation for electrons gave rise to what are now call quantum numbers and only certain combination of values are possible. 3. While looking at this string vibrating, you can now relate this to the probability of finding electrons in a tight, tiny region of space. In 1926, Erwin Schrodinger developed an equation that took into account the wavelike nature of the electron. The solution to his equation represents the probable location of an electron around the nucleus. Just like a guitar string, there is a lowest

L

L= 12 λ1

Fundamental or rst harmonic, ƒ1

L= λ2

First overtone or second harmonic, ƒ2 = 2ƒ1

L=

3 2

λ3

Second overtone or third harmonic, ƒ3 = 3ƒ1

Figure 3-7  Only certain waves are possible for electrons in an atom, which defines the energy of an electron in terms of wave functions. © Jones & Bartlett Learning.

energy solution and higher energy ones. The solutions to the Schrodinger equation yield a set of numbers that describe the orbital’s size, shape, and orientation in space. For our purposes, the actual equation and numerical solutions are not important. However, knowing of the existence of these “wave functions” or orbitals can help you better understand the behavior of the atoms.

Orbitals and the “Shell Model” In the shell model, the maximum number of electrons that fit in each shell is defined. After taking into account the wavelike properties of the electron and understanding that there are different possible frequencies in a standing wave, you can incorporate this understanding to the electron shells. The shells in this model represents a group of orbitals that are close in energy to each other, but not exactly the same. Recall that the first shell in the shell model could hold a maximum of two electrons. Because each atomic orbital can hold a maximum of two electrons, that first shell represents just one wave function, or orbital. The pictorial representation of that probability density is as follows, kind of like a sphere or a ball surrounding the nucleus. The first shell only contains one “s” orbital that is shaped like a ball and can only contain two electrons Figure 3-8 .

58

Hazardous Materials Chemistry, Third Edition

Z

Y

X

Figure 3-8  An “s” orbital can contain a maximum of two electrons. © Jones & Bartlett Learning.

The second shell in the model held a maximum of 8 electrons. This shell is larger and contains more than one type of orbital. The lowest-energy orbital in each new shell is the spherical one, represented above. Chemists call this type of orbital the “s” orbital. The second shell contains another type of orbital beside an s orbital. It also contains three “p” orbitals. The p orbitals in the second shell, when in atoms, have the same energy and shape as each other, but are oriented in different directions in space. A “p” orbital looks kind of like a figure 8 Figure 3-9 . Z

x

Z

Z

y x

Z

y x Pz

y Px

x

y Py

Figure 3-9  A “p” orbital looks like a figure 8. © Jones & Bartlett Learning.

Since the second shell contains one s orbital and three p orbitals (each p orbital is on each axis of a plane, x, y, and z, and contains two electrons per orbital), the second shell can hold a maximum of eight electrons (two in the s orbital, and six in the p orbitals for a total of eight), since each orbital can represent two electrons. The third shell also contains one s orbital and three p orbitals and also holds a maximum of eight electrons (again two in the second s orbital, and six in the p orbitals, for a total of eight). Therefore, on the periodic chart, an atom such as argon has two electrons in the first s orbital, eight electrons in the

second s and p orbitals, and another eight in the third s and p orbitals, giving it a total of 18 electrons with all the orbitals full and rather stable! The fourth shell can hold a maximum of 18 electrons, which means that the fourth shell must contain more orbitals. The fourth shell of an atom can contain orbitals that chemists call the “d” orbitals. The shape and orientation of these orbitals are beyond the scope of this book, but in each shell that can contain d orbitals, there will be five d orbitals of approximately equal energy when in an atom. Because each of these five orbitals can represent two electrons, the fourth shell can hold 10 more electrons, for a total of 18. That’s because the fourth shell contains an s orbital, three p orbitals and five d orbitals each containing two electrons, for an additional 10 electrons, there is a total of 18 electrons. The fifth shell also contains one s orbital, three p orbitals, and five d orbitals. With each individual orbital potentially representing two electrons, the fifth shell can hold 18 electrons as well. Finally the sixth and seventh shells can hold a maximum of 32 electrons. The additional type of orbitals in these shells is called the “f” orbital. In each of these shells, there are seven f orbitals of equal energy that can each represent two electrons. This allows the sixth and seventh shells the ability to hold 14 more electrons, for a total of 32.

Atomic Orbitals and the Periodic Table How then do atomic orbitals relate to the periodic table? Recall that in the simple shell model, the maximum number of electrons for each shell also corresponded to the number of elements in that row of the periodic table. For example, the first shell holds two electrons and the first row of the periodic table contains two elements. The second shell holds eight electrons and the second row of the periodic table contains eight elements Figure 3-10 . You can quickly determine what type of orbitals are in an atom’s valence shell and which electrons are involved in bonding by locating that element on the periodic table. Consider the second row of the periodic table. The first element in the second row is lithium. Lithium contains a total of three electrons. The first two electrons occupy the first shell. The third electron occupies the s orbital in the second shell. Now locate carbon to the right of lithium in that same row. Carbon has a total of six electrons. The first two fill the first shell. The next four are valence electrons. Two electrons occupy the s orbital and the other two occupy p orbitals. In general, chemists refer to the first two columns of the periodic table as the “s” block. Every element in the first two rows has valence electrons that occupy s orbitals. Columns 13–18 are referred to as the “p” block. With the exception of He, all of the elements in groups 13–18 have valence shells that contain s orbitals and p orbitals that are at least partially occupied. (Those elements in the fourth row and lower have full d orbitals as well.) Groups 3–12 are the “d” block. All the elements in this region of the periodic table have valence shells that contain two s electrons and at least partially filled d orbitals. Finally, the lanthanides and actinides represent the f block.

Chapter 3 The Atom

1s1

59

1s2

2s1

2s2

2p1

2p2

2p3

2p4

2p5

2p6

3s1

3s2

3p1

3p2

3p3

3p4

3p5

3p6

4s1

4s2

3d1

3d2

3d3

3d5

3d5

3d6

3d7

3d8

3d10

3d10

4p1

4p2

4p3

4p4

4p5

4p6

5s1

5s2

4d1

4d2

4d4

4d5

4d5

4d7

4d8

4d10

4d10

4d10

5p1

5p2

5p3

5p4

5p5

5p6

6s1

6s2

5d2

5d3

5d4

5d5

5d6

5d7

5d9

5d10

5d10

6p1

6p2

6p3

6p4

6p5

6p6

7s1

7s2

6d2

6d3

6d4

6d5

6d6

6d7

6d8

6d10

6d10

7p1

7p2

7p3

7p4

7p5

7p6

5d1

4f1

4f3

4f4

4f5

4f6

4f7

4f7

4f9

4f10

4f11

4f12

4f13

4f14

4f11

6d1

6d2

5f2

5f3

5f4

5f6

5f7

5f7

5f9

5f10

5f11

5f12

5f13

5f14

5f14

Figure 3-10  The periodic table with a simplified summary of unfilled subshells.

Problem Set 3-1 1. For the first 12 elements on the periodic table, determine the number of shells and electrons within each shell.

Problem Set 3-2 1. Given a “number” determine the element and the other ­“numbers” that are associated with it: Name

Atomic Number

Mass Number

Number of Protons

Number of Electrons

 8 20 22  9 13 85 17

Ion Formation Elements in the “s” block primarily lose their valence s electrons when involved in chemical reactions. The only exception is hydrogen, which can lose its electron, gain another, and share it.

Nonmetals in the p block can gain electrons or share their valence electrons to form molecular compounds. You will see later in the text that most nonmetals undergo chemistry that results in the atom being surrounded by at least eight electrons. Understanding the existence of additional orbitals, besides s and p, explains why certain elements can have more than eight electrons. You may notice that certain p block metals have stable charges that would correspond to losing only p electrons or losing s and p electrons. For example, lead is stable with oxidation numbers +2 and +4. Metals in the d block do interesting chemistry with electrons originally in d atomic orbitals. You may notice that most transition metals are stable at +2 charge. This corresponds to losing the two s electrons. With five d orbitals that can split into different energies depending on the chemical environment, you can now understand why transition metals can have a variety of stable oxidation numbers. As discussed before, atoms that are electrically neutral have the same number of electrons as protons. When atoms gain or lose electrons when forming ionic compounds, they may end up with a different number of electrons than protons. Because the number of protons does not vary, the element does not change. However, if there are fewer electrons than protons, the atom will be positively charged, thus forming a cation (positive ion). With more electrons than protons, the atom is negatively charged and forms an anion (negative ion). Elements in the p block (the right side of the periodic table) gain or share electrons to fill their valence shell. When they gain electrons outright, they become anions.

60

Hazardous Materials Chemistry, Third Edition

With a basic understanding of the electronic structure of the atom, one can predict a great amount of chemistry of the elements. Because metals in group 1 have one electron in their valence shell, group 1 metals will react to form +1 cations. Group 2 metals have 2 valence electrons and will react to form +2 cations. Elements of the right side of the periodic table, on the other hand react either to form anions by gaining enough electrons to fill their valence shell or react in such a way with other nonmetals to share electrons. The result is usually a bond where each element shares the number of electrons needed to obtain a full valence shell. With this simple model of the atom, you can understand why metals lose electrons to form cations and nonmetals either gain electrons to form anions or share electrons to form molecular compounds. A more thorough discussion of chemical bonding will be continued in Chapter 4, Bonding.

behavior of electrons in those atoms, there are certain trends that can be predicted between atoms based on their relative location on the periodic table.

Atomic Radii Atomic radii can be defined in more than one way, but no matter the definition used, the trends among atoms on the periodic table are the same. The more obvious trend that can be predicted is the one among atoms in the same column of the periodic table. The atoms arranged in the same column all have very similar electron configurations in their valence shell. This biggest difference is that atoms placed lower in a column of the periodic table have a valence shell that is farther away from the nucleus than atoms arranged higher. Therefore, the first trend regarding size is: atoms in the same group on the periodic table get bigger as you move down the group. Now consider atoms located in the same row on the periodic table. As you move across a row, both the number of protons and the number of electrons in the neutral atom increase. However, those electrons are placed in the same shell as the electrons prior and are not located any farther away from the nucleus, while at the same time, the added proton in the nucleus is increasing the charge in the nucleus and increasing the attraction the electrons have to the nucleus. Having a greater nuclear charge causes the electrons to be pulled in closer to the nucleus. Therefore the second trend regarding size is: atoms in the same row on the periodic table get smaller as you move across. The overall trend regarding atoms is summarized in Figure 3-11 .

ALERT The reactions that occur between groups 1 (IA) or 2 (IIA) and group 7 (VIIA) may be explosively violent.

Periodic Trends Because the elements in the periodic table are ordered by the number of protons in the nucleus and the elements have been arranged in such a way that atoms with similar chemical properties are grouped together in columns, and because the similarity in chemical properties can be explained by understanding the

Periodic Table of the Elements Atomic Radius

1H

3Li

2He

4Be

Atom sizes are relative to the largest element, cesium. Dimmed elements have no data. Elements 87, 88 and 104-118 have no data and were omitted.

5B

6C

7N

8O

9F

10Ne

13AI

14Si

15P

16S

17Cl

18Ar

11Na

12Mg

19K

20Ca

21Sc

22Ti

23V

24Cr

25Mn

28Fe

27Co

28Ni

29Cu

30Zn

31Ga

32Ge

32As

34Se

35Br

36Kr

37Rb

38Sr

39Y

40Zr

41Nb

42Mo

43Tc

44Ru

45Rn

46Pd

47Ag

48Cd

49In

50Sn

51Sb

52Te

53I

54Xe

55Cs

56Ba

72Hf

73Ta

74W

75Re

76Os

77lr

78Pt

79Au

80Hg

81TI

82Pb

83Bi

84Po

85At

86Rn

57La

58Ce

59Pr

60Nd

61Pm

62Sm

63Eu

64Gd

65Tb

66Dy

67Ho

68Er

69Tm

70Yb

71Lu

89Ac

90Th

91Pa

92U

93Np

94Pu

95Am

96Cm

97Bk

98Cf

99Es

100Fm

101Md

102No

103Lr

Figure 3-11  A periodic table showing the relative sizes of atoms.

Chapter 3 The Atom

Keep in mind that this broad trend does not always hold true between individual atoms. For example, there are variations in this trend between individual transition metals. However, understand this broad trend can help you predict some important patterns in chemical reactivity.

Ionization Energy and Electron Affinity The ease with which atoms lose electrons and the tendency of atoms to gain electrons can also be predicted based on an atom’s position on the periodic table Figure 3-12 . First consider the trend noticed within elements in the same group. Because the valence electrons get farther away from the nucleus as you move down a group on the periodic table, you can state that: atoms lose electrons more easily as you move down a group on the periodic table. Now consider elements within the same row. You know how atoms get smaller as you move across a row because the charge of the nucleus increases going across a row. For this same reason: electrons are harder to remove from atoms as you move across a period on the periodic table. The energy needed to remove an electron from an atom is called ionization energy. This energy gets smaller as you move down a group. This energy gets bigger as you move across a period. For the purposes of this text, first ionization energies or the energy required to remove one electron from an atom shall be discussed. There

are some exceptions to this overall trend that can be explained by electron configuration. For example, is it easier to remove an electron from boron than beryllium even though boron lies to the right of beryllium on the periodic table. This is because the outermost electron configuration of boron contains two 2 s and 1 p electrons. It is easier to remove that single unpaired p electron from boron than one of the two paired electrons in beryllium Figure 3-13 . The relative tendency of atoms to gain electrons can also be predicted based on their positions on the periodic table. In general, atoms that lose electrons easily do not attract electrons easily, so the tendency for electrons to gain electrons is opposite the trend for losing electrons. The tendency for an atom to gain electrons is measured by its electron affinity. Electron affinity is defined as the change in energy when an electron is added to an atom in the free gaseous state to form an anion. Energy is needed to remove electrons from atoms, so ionization energies are positive. However, energy is usually released when an electron is put into an atom, so most electron affinities are negative. The larger the magnitude of the negative value, the more attracted that atom is to electrons. For example, chlorine, a nonmetal with nearly a complete valence shell, has an electron affinity of −349 kJ/mol, whereas sodium, a metal that has a greater tendency to lose electrons, has an electron affinity of −53 kJ/mol. The greater negative value of chlorine indicates that chlorine has a greater affinity for electrons Figure 3-14 .

Stronger in electronegativity; ionization potentials increase as atomic radius decreases

Atomic radius increases, making the atoms larger and heavier; metallic qualities increase

Stronger in electronegativity, ionization potentials increase along with increase in atomic number; atomic radius decreases

Atomic radius increases, making the atoms heavier; metallic qualities increase

Figure 3-12  Generalized relationships across the periodic table. © Jones & Bartlett Learning.

61

62

Hazardous Materials Chemistry, Third Edition

1

2

He

H Ionization Energy

(1.00784; 1.00811) HYDROGEN

3

5

6

Li

Be

B

3 (6.938; 6.997) LITHIUM

4. 9.0122 BERYLLIUM

[10.806;10.821] BORON

11

12

13

7

8

C

N

[12.0096;12.0116] [14.00643;14.00] CARBON NITROGEN

14

9

15

10

O

F

[15.999;159997] OXYGEN

18.9984032 FLUORINE

16

17

Ne 20.1797 NEON

18

Na

Mg

Al

Si

P

S

Cl

Ar

22.990 SODIUM

24.305 MAGNESIUM

26.982 ALUMINUM

[28.084;28.086] SILICON

30.974 PHOSPHORUS

[32.059;32076] SULFUR

[35.446;35.457] CHLORINE

39.948 ARGON

19

Increases

4.0026 HELIUM

4

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

39.098 POTASSIUM

40.078 CALCIUM

44.956 SCANDIUM

47.867 TITANUM

50.942 VANADIUM

5.996 CHROMUM

54.938 MANGANESE

55.845 IRON

58.9332 COBALT

58.6934 NICKEL

63.546 COPPER

65.392 ZINC

69.723 GALLIUM

69.723 GERMANIUM

74.9216 ARSENIC

78.963 SELENIUM

79.904 BROMINE

83.801 KRYPTON

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

85.468 RUBIDIUM

87.62 STRONTIUM

88.90585 YTTRIUM

91.224 ZIRCONIUM

92.90638 NIOBIUM

95.94 MOLYBDENUM

98.907 TECHNETIUM

101.07 RUTHENIUM

102.9055 RHODIUM

3106.42 PALLADIUM

107.8682 SILVER

112.411 CADMIUM

114.818 INDIUM

114.818 TIN

121.76 ANTIMONY

127.603 TELLURIUM

126.90447 IODINE

131.292 XENON

55

56

Cs 132.90545 CESIUM

87

57-71

137.327 BARIUM

88

Fr 223.02 FRANCIUM

72

LANTHANIDES

89-103

227.027 ACTINIUM

57

LANTHANIDES

75

76

77

78

79

80

81

82

83

84

85

86

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

178.49 HAFNIUM

180.95 TANTALUM

183.84 TUNGSTEN

186.207 RHENIUM

190.233 OSMIUM

IRIDIUM IRIDIUM

195.084 PLATINUM

196.96655 GOLD

200.59 MERCURY

[204.382;204.385] THALLIUM

204.383 LEAD

208.98038 BISMUTH

209.982 POLONIUM

209.987 ASTATINE

104

105

106

107

108

109

110

Rf

Db

Sg

Bh

Hs

Mt

263.113 RUTHERFORDIUM

262.114 DUBNIUM

266.122 SEABORGIUM

264.125 BOHRIUM

269.134 HASSIUM

268.159 MEITNERIUM

58

59

60

61

62

111

Ds

63

112

Rg

272.146 294 DARMSTADTIUM ROENTGENIUM

64

65

113

Cn

Uut

277 COPERNICIUM

284 UNUNTRIUM

66

67

114

115

116

Uuq Uup Uuh 284 288 UNUNQUADIUM UNUNPENTIUM

68

69

292 UNUNHEXIUM

70

117

Uuo 294 UNUNOCTIUM

71

Pr

Nd

Pm

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

138.905 LANTHANUM

140.116 CERIUM

140.90765 PRASEODYMIUM

144.242 NEODYMIUM

144.913 PROMETHIUM

150.362 SAMARIUM

151.964 EUROPIUM

157.253 GADOLINIUM

158.92534 TERBIUM

162.5 DYSPROSIUM

164.93032 HOLMIUM

167.259 ERBIUM

168.93421 THULIUM

173.043 YTTERBIUM

174.967 LUTETIUM

91

92

93

94

95

96

97

98

99

100

101

222.018 RADON

118

Uus

Ce 90

Rn

294 UNUNSEPTIUM

La 89

ACTINIDES

74

Ta

Ra Ac-Lr 226.254 RADIUM

73

Hf

Ba La-Lu

102

103

Ac

Th

Pa

U

Np

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

227.027 ACTINIUM

232.0381 THORIUM

231.03588 PROTACTINIUM

238.02891 URANIUM

237.048 NEPTUNIUM

244.064 PLUTONIUM

243.061 AMERICIUM

247.07 CURIUM

247.07 BERKELIUM

251.08 CALIFORNIUM

252.83 EINSTEINIUM

257.095 FERMIUM

258.098 MENDELEVIUM

259.101 NOBELIUM

262.11 LAWRENCIUM

Increases Figure 3-13  Ionization energies in the periodic table.

Period

Electron Affinity Values for Selected Elements (kJ/mol) Group 1 H 1 -72

18 He +20*

2 Li -60

2 Be +240*

13 B -23

14 C -123

15 N 0

16 O -141

17 F -322

3 Na -53

Mg +230*

Al -44

Si -120

P -74

S -20

Cl -348

Ar +35*

4 K -48

Ca +150*

Ga -40*

Ge -115

As -7

Se -195

Br -324

Kr +40*

5 Rb -46 6 Cs -45 7

Fr

Ne -30

3 Sc

4 Ti

5 V

6 Cr

7 Mn

8 Fe

9 Co

10 Ni

11 Cu

12 Zn

Sr +160*

Y

zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In -40*

Sn -121

Sb -101

Te -190

I -295

Xe +40*

Ba +50*

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl -50

Pb -101

Bi -101

Po -170

At -270*

Rn +40*

Ra *Calculated value

Figure 3-14  Electron affinities.

Chapter 3 The Atom

Electronegativity There are two properties that describe an atom’s tendency to gain or attract electrons. The first property, previously discussed, is called electron affinity. Electron affinities describe the attraction of single atoms in the gas phase (not involved in bonds) to electrons. Atoms that want to gain electrons have large negative electron affinities. The second property that describes an atom’s tendency to attract electrons is called electronegativity and refers to an atom’s ability to attract electrons to itself when involved in a chemical bond. Atoms that attract electrons well are referred to as electronegative. Atoms that do not attract electrons well are referred by some as electropositive. Electronegativities are calculated using measured electron affinities and ionization energies. Using both properties, elements in the upper right attract electrons better than elements in the lower left. Like the other trends, this overall trend has exceptions that are easily explained when the electron configuration of the atoms are well understood. For example, fluorine has both a larger negative electron affinity and a higher electronegativity than helium. This is because helium, with a full valence shell, does not need to attract any electrons to be stable. Therefore, electronegativity is a property that quantifies how tightly electrons are held by an

Technical Note Electronegativity was a concept known to chemists before a quantitative scale for it was proposed by Linus Pauling in 1932. Linus Pauling earned the Nobel Prize in chemistry in 1954 based on his work on the nature of the chemical bond. Although other numeric electronegativity scales were developed for electronegativity, Linus Pauling’s scale is still the one that is most widely used.

Problem Set 3-3 1. From the table in Problem Set 3-2 and using your understanding of ionization, which element is the most electronegative?

ALERT The alkali metals are very reactive and are not found freely in nature. These metals have only one electron in the outer shell, giving them a strong tendency to react and form an ionic bond.

atom when part of chemical bond. Noble gases, since they do not participate in chemical bonding, are not considered when discussing electronegativity. Fluorine is the most electronegative atom on the periodic table. In general, the closer an element is to fluorine, the more electronegative it is Figure 3-15 .

Bonding Basics With a basic understanding of valence electron configuration, you can now begin discussing the behavior of electrons to form chemical bonds. Conventional chemical reactivity is about the behavior of the electrons between the atoms involved in bonding. Chemical bonds are formed due to the transfer or sharing of electrons. When a chemical bond is formed as a result of electrons from one atom being transferred to another atom, that bond is called an ionic bond. What happens in an ionic bond is that an atom with a low ionization energy (loses electrons readily) loses one or more electrons, which are then transferred

H 2.1

Li 1.0 Na 0.9 K 0.8 Rb 0.8 Cs 0.7

B 2.0

Be 1.5

Al 1.5

Mg 1.2 Ca 1.0 Sr 1.0 Ba 0.9

Sc 1.3

Ti 1.5

Y 1.2

Zr 1.4

La 1.0

Hf 1.3

Figure 3-15  Electronegativity.

V 1.6

Cr 1.6

Mn 1.5

Nb 1.6

Mo 1.8

Tc 1.9

W 1.7

Re 1.9

Ta 1.5

63

Fe 1.8

Co 1.9

Ni 1.9

Cu 1.9

Ru 2.2

Rh 2.2

Pd 2.2

Ag 1.9

Os 2.2

Ir 2.2

Pt 2.2

Au 2.4

C 2.5

Sl 1.8

N 3.0

P 2.1

Ge 1.8

As 2.0

In 1.7

Sn 1.8

Sb 1.9

Tl 1.8

Pb 1.9

Bi 1.9

Zn 1.6

Ga 1.6

Cd 1.7 Hg 1.9

F 4.0

O 3.5

S 2.5 Se 2.4 Te 2.1 Po 2.0

Cl 3.0

He

Br 2.8

Ne

I 2.5 Al 2.1

Ar Kr Xe Rn

64

Hazardous Materials Chemistry, Third Edition

to an atom with a large negative electron affinity (an atom that gains electrons readily). The result of that electron transfer is an atom with a positive charge because that atom has fewer electrons than protons in the nucleus, and an atom with a negative charge, because that atom has more electrons than protons in the nucleus. Because opposite charges attract, the positive atom, or cation, is bonded to the negative atom, or anion. For example, sodium is an atom with one valence electron, so sodium reacts in a way to lose that valence electron and become positively charged with a full outermost shell as a result Figure 3-16 . Chlorine is an atom with one fewer electron than is needed for a full valence shell. As a result, chlorine reacts in a way to either gain an electron from another atom or share one with another atom to complete its valence shell. When chlorine reacts with sodium, sodium will transfer its valence electron to chlorine. Sodium will end up +1, chlorine will end up -1, and the two opposite charges will attract to form sodium chloride, or table salt.

11P 11N

11P 11N

11e-

10eNa (neutral)

Na+

Figure 3-16  In becoming a positive ion, the neutral sodium atom decreases in size once its electron has been given up. © Jones & Bartlett Learning.

The other type of chemical bond results from the sharing of electrons. Remember, chlorine can become stable by either gaining an electron from electron transfer or sharing an electron with another atom to complete its valence shell. The element chlorine exists as a molecule consisting of two atoms. In this molecule, each chlorine shares an electron with the other so that each is stabilized by having a complete valence shell. The chemical bond that is the result of the sharing of electrons is known as a covalent bond. A rudimentary way of determining the type of bonding that is occurring between atoms in a compound can be determined based on the identity of the atoms. In general, ionic bonds are formed between metals and nonmetals. Metals tend to have low ionization energies and nonmetals have large negative electron affinities. The chemical bond formed between two nonmetals will be covalent. In general, metals do not bond to each other.

General Characteristics Alkali Metals Group 1 (1A) elements listed in the first column or group on the left on the periodic table are alkali metals, and include lithium, sodium, potassium, rubidium, cesium, and francium. They are highly reactive in their pure forms. The elements in this group give up an electron easily because there is only one electron in the outer shell. Therefore, it is rare that any of this group is found in its pure form. In nature, all are found as cations in salts (ionic compounds).

Group 1 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

1

Hydrogen

H

1s1

1s1

3

Lithium

Li

1s22s1

[He] 2s1

11

Sodium

Na

1s22s22p63s1

[Ne] 3s1

19

Potassium K

1s22s22p63s23p64s1

[Ar] 4s1

37

Rubidium

Rb

1s22s22p63s23p6 3d104s14p65s1

[Kr] 5s1

55

Cesium

Cs

1s22s22p63s23p6 3d10 4s24p64d105s25p66s1

[Xe] 6s1

87

Francium

Fr

1s22s22p63s23p6 3d10 [Rn] 7s1 4s14p64d105s25p65d10 6s26p67s1

The reactions of these elements are so violent that only sodium, lithium, and potassium are used commercially. The chemicals in this group are highly water-reactive and prone to ignition on exposure to moist air. They produce strong caustic solutions that can result in severe burns to the eyes, skin, and respiratory system. In addition, they will produce hydrogen gas on contact with water.

Alkaline Earth Metals Group 2 (IIA) elements listed in the second column or group from the left on the periodic table are the alkaline earth metals, and include beryllium, magnesium, calcium, strontium, barium, and radium. These elements appear to be gray with a metallic brilliance. Some of the common commercial uses of these elements relate to their radioactive qualities. Magnesium is used in metal alloys and beryllium is used in the hazmat industry for nonsparking tools. As with the first group, this second group is also very reactive. These elements have two electrons in the outermost shell and freely release them to form cations with a charge of +2. They react with acids, releasing hydrogen gas that Group 2 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

4

Beryllium

Be

1s22s2

[He] 2s2

12

Magnesium

Mg

1s22s22p63s2

[Ne] 3s2

20

Calcium

Ca

1s22s22p63s23p64s2

[Ar] 4s2

38

Strontium

Sr

1s22s22p63s23p6 3d10 4s24p65s2

[Kr] 5s2

56

Barium

Ba

1s22s22p63s23p6 3d10 4s24p64d105s25p66s2

[Xe] 6s2

88

Radium

Ra

1s22s22p63s23p6 3d10 [Rn] 7s2 4s24p64d105s25p65d10 6s26p67s2

Chapter 3 The Atom

is extremely flammable. In addition, they are water-reactive, produce solutions that may be caustic, and have the potential to ignite in air if heated. Like the metals in Group 1, the Group 2 metals react more violently moving down the group.

Group 13 Atomic No Name

Electron Symbol Configuration

Transition Metals

5

Boron

B

The next 10 groups, Groups 3–12 (groups IIIB–IIB), are called the transition metals. These are stable as elements. Some are resistant to corrosion and some are not. Those that are resistant to corrosion are known as the noble metals. Some transition metals have a distinct ability to have several valence numbers because they can combine with other elements utilizing electrons that occupy suborbitals within the valence shell. This is the reason that you will find several valence numbers for most of these elements. These are metals that conduct electricity and heat. Hemoglobin within the blood contains an iron atom that readily accepts oxygen for transportation through the arterial cardiovascular system. The bonding of oxygen to the hemoglobin molecule forms oxyhemoglobin. This bond is weak and enables the red blood cell to carry oxygen to the cells. Once at the cell, the bond is broken. There are several other configurations that are stronger than the oxygen-to-hemoglobin bond, thus not allowing oxygen transfer; for example, sulfhemoglobin, ­carboxyhemoglobin, and methemoglobin.

13

Technical Note Carbon and oxygen sometimes combine to produce carbon monoxide (CO). Once CO is attached to hemoglobin, a very stable bond is created. Hemoglobin contains iron, which is where the carbon monoxide bonds. The new compound is called carboxyhemoglobin. This molecule is so stable that oxygen can no longer attach to the red blood cell, causing chemical asphyxiation.

All of the elements in this area of the periodic table are true metals, some of which are referred to as the heavy metals. These elements pose health hazards that are frequently monitored for medical consequences.

Condensed Electron Configuration

1s22s2 2p1

[He] 2s22p1

Aluminum Al

1s22s22p63s23p1

[Ne] 3s23p1

31

Gallium

Ga

1s22s22p63s23p6 3d104s24p1

[Ar] 3d104s24p1

49

Indium

In

1s22s22p63s23p6 3d104s24p64d10 5s25p1

[Kr] 4d105s25p1

81

Thallium

Tl

1s22s22p63s23p6 3d10 4s24p64d104f145s2 5p65d106s26p1

[Xe] 4f145s15p6 5d106s26p1

113

Ununtrium Uut

1s22s22p63s23p63d10 4s24p64d104f145s2 5p65d105f146s2 6p66d107s27p1

[Rn] 5f146s16p6 6d107s27p1

Group 14 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

5

Carbon

C

1s22s2 2p2

[He] 2s22p2

14

Silicon

Si

1s22s22p63s23p2

[Ne] 3s23p2

32

Germanium Ge

1s22s22p63s23p6 3d104s24p2

[Ar] 3d104s24p2

50

Tin

Sn

1s22s22p63s23p6 3d104s24p64d10 5s25p2

[Kr] 4d105s25p2

82

Lead

Pb

1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d10 6s26p2

[Xe] 4f145s2 5p65d106s26p2

114

Flerovium

Fl

1s22s22p63s23p6 3d104s24p64d104f14 5s25p65d105f146s2 6p66d107s27p2

[Rn] 5f146s2 6p66d107s27p2

Aluminum Family Group 13 on the periodic table of elements are the aluminum family of metals and one nonmetal; namely boron, aluminum, gallium, indium, and thallium. Their physical state is solid for the most part (gallium has a low melting point at 86°F). The general hazards of this group are poisoning and other varied effects depending on the element combination. Boron is used in flares and some of the pyrotechnic rockets; it gives fireworks their distinctive green color. Although not a potent poison, it may result in chronic toxic effects if ingested. Indium is primarily used for making low-melting alloys and is toxic through inhalation. Thallium is a toxic substance; the compound thallium sulfate was mostly used in rodenticides during the 1970s. Because of its highly toxic qualities, household availability of thallium is prohibited.

65

Germanium Family Group 14 of the periodic table represents the germanium family of elements: carbon, silicon, germanium, tin, and lead. These elements range from gray-black to silvery white and are all solids that have high densities. Germanium initially did not have many industrial applications; however, with the introduction of computers and the Internet, this element has found many useful industrial applications. It also has been found to be advantageous in fighting specific bacteria, which makes it highly useful in the medical field. Lead is a toxic heavy metal that, much like mercury, can cause a variety of central nervous system disorders. The toxic effects of lead are long term, which is one reason why lead is no longer used in plumbing or as a tint in white paint.

66

Hazardous Materials Chemistry, Third Edition

Sulfur Family

Technical Note Mercury and lead poisoning are examples of heavy metal toxicity. In the early 1800s, the effect of mercury was noted among those individuals who made hats (hatters), as mercury was used in the final stages of hat production. The hatter was directly exposed to the mercury fumes, which caused a variety of nervous system dysfunctions and hyperactivity. Thus the phrase “mad as a hatter,” which was highlighted in the book Alice’s Adventures in Wonderland. It is also thought that the Romans used lead in their water aqueduct system and to sweeten wine. This intake of high quantities of lead, and the resulting lead poisoning, was thought to have contributed to the fall of the Roman Empire.

General hazardous characteristics of this group are heavy-metal poisoning and other varied effects depending on the element combination.

Nitrogen Family Group 15 on the periodic table makes up the nitrogen family, which includes nitrogen, phosphorus, arsenic, antimony, and bismuth. In this group, nitrogen is the only element that is a gas; the rest are solids. The general hazards of this group are heavy-metal poisoning and other varied effects depending on the element combination. For example, phosphorus is pyrophoric in certain forms.

Group 15 Electron Symbol Configuration

7

Nitrogen

N

1s22s2 2p3

[He] 2s22p3

15

Phosphorus

P

1s22s22p63s23p3

[Ne] 3s23p3

33

Arsenic

As

1s22s22p63s23p6 3d104s24p3

[Ar] 3d104s24p3

1s22s22p63s23p6 3d104s24p64d10 5s25p3

[Kr] 4d105s25p3

1s22s22p63s23p6 3d104s24p64d104f14 5s25p65d106s26p3

[Xe] 4f145s25p6 5d106s26p3

1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d105f14 6s26p66d107s27p3

[Rn] 5f146s26p6 6d107s27p3

Antimony

Sb

83

Bismuth

Bi

115

Ununpentium Uup

Group 16 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

8

Oxygen

O

1s22s2 2p4

[He] 2s22p4

16

Sulfur

S

1s22s22p63s23p4

[Ne] 3s23p4

34

Selenium

Se

1s22s22p63s23p6 3d104s24p4

[Ar] 3d104s24p4

52

Tellurium

Te

1s22s22p63s23p6 3d104s24p64d10 5s25p4

[Kr] 4d105s25p4

84

Polonium

Po

1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d10 6s26p4

[Xe] 4f145s25p6 5d106s26p4

116

Livermorium Lv

1s22s22p63s23p6 3d104s24p64d104f14 5s25p65d105f146s2 6p66d107s27p4

[Rn] 5f146s26p6 6d107s27p4

Halogens Condensed Electron Configuration

Atomic No Name

51

Group 16 on the periodic table is the sulfur family, sometimes called the chalcogen family, and consists of oxygen, sulfur, selenium, tellurium, and polonium. The first two concern us most because they are the most prevalent. These elements are moderately reactive. The general hazards of this group are heavy-metal poisoning and other varied effects depending on the element combination.

The aluminum group is sometimes referred to as the “other metals.” Although ductile and malleable like the transition elements, their valence electrons are from the s and p orbitals. For use in this text, the valence is +3, but some of these elements may have valences of +3, +4, –4, or –3. All are solids.

Group 17 on the periodic table are the halogens, consisting of fluorine, chlorine, bromine, iodine, and astatine. This group of elements is one of the most widely used groups of chemicals. These Group 17 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

9

Fluorine

F

1s22s2 2p5

[He] 2s22p5

17

Chlorine

Cl

1s22s22p63s23p5

[Ne] 3s23p5

35

Bromine

Br

1s22s22p63s23p6 3d104s24p5

[Ar] 3d104s24p5

53

Iodine

I

1s22s22p63s23p6 3d104s24p64d10 5s25p5

[Kr] 4d105s25p5

85

Astatine

At

1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d10 6s26p5

[Xe] 4f145s25p6 5d106s26p5

117

Ununseptium Uus

1s22s22p63s23p6 3d104s24p64d104f14 5s25p65d105f14 6s26p66d107s27p5

[Rn] 5f146s26p6 6d107s27p5

Chapter 3 The Atom

chemicals are all toxic and produce a variety of serious health effects. This group is utilized in the production of the halons. They are corrosive, irritating, and strong oxidizers. Great care should be exercised during a hazmat operation involving these elements. Because all of the halogens have one fewer electron than is necessary for a full valence shell in the elemental form, all exist as molecules that contain two atoms. Each atom of the halogen shares one electron with the other so that each atom seems to have a full valence shell. Also, when halogens react with metals, they gain 1 electron and become anions with a –1 charge.

The halogens, or the salt-formers, have one fewer electron in their outermost shell than is needed to be full, therefore they gain one electron and have a charge of -1 when part of an ionic compound. Halogens can substitute for hydrogen in methane or ethane, resulting in a nonflammable, colorless gas that can be used as an extinguishing agent. In this configuration, they represent an asphyxiation hazard.

The elements in groups 16 and 17 are mostly nonmetal. The nonmetals do not conduct electricity well. They can exist in any of the three states of matter at room temperature. Valence numbers can be ascertained from their position on the periodic table. The metalloids (refer to the periodic chart in Figure 3-5) are the elements that are between the metals and the nonmetals. They have properties of both the metals and the nonmetals.

Group 18 Condensed Electron Configuration

Atomic No Name

Electron Symbol Configuration

2

He

1s2

Ne

2

2

2

2

6

2

6

[Ar]

2

2

6

2

6

10 18

Neon Argon

Ar

[He] 6

1s 2s 2p

[Ne]

1s 2s 2p 3s 3p

36

Krypton

Kr

1s 2s 2p 3s 3p 3d104s24p6

[Kr]

54

Xenon

Xe

1s22s22p63s23p6 3d104s24p64d10 5s25p6

[Xe]

86

Radon

Pn

1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d10 6s26p6

[Rn]

118

Noble Gases Group 18 on the periodic table is known as the noble gases and is made up of helium, neon, argon, krypton, xenon, and radon. All the elements in this group are stable without the introduction of energy and are sometimes referred to as inert gases. The reason for their stability is that the outer shell is full. Commercial use is focused on this extreme stability and non-reactivity, such as inerting pipelines and as pipeline pigs. The general hazard of this group is that these elements are displacement asphyxiants.

Radiation

ALERT

Helium

67

Ununoctium Uuo

1s22s22p63s23p6 [Uuo] 3d104s24p64d10 4f145s25p65d10 5f146s26p66d107s27p6

Emergency responders are exposed to a variety of hazards, not the least of which is radiation. Radiation is all around us. The common forms seem not so threatening: sunshine and diagnostic medical procedures such as X-rays and medicines, for example. However, the topic of nuclear power strikes fear into the hearts of emergency responders and the public alike. But it’s basically a fear of the unknown. In fact, radiological accidents are few. Other hazard classifications are responsible for larger and more frequent releases. As with anything else, it is increased understanding that reduces fears and provides the capability for handling these types of releases.

ALERT In addition to their radioactive qualities, heavy metals, found at the bottom of the periodic table, may have additional hazards associated with them.

A variety of compounds are used in the nuclear power industry, but most are metal salts. Even though the following discussion focuses on radiological hazards, never forget that these compounds can undergo other chemical reactions as well and pose other hazards in addition to radiation. An understanding of the subatomic particles gives rise to the understanding of radiation. Recall that the atomic number found on the periodic table represents the number of protons, which in turn represents the number of electrons in a neutral atom. Adding the number of protons and the number of neutrons gives the mass number (A). For example, uranium can be shown as U-238, where the atomic number is 92 and the mass number is 238 (i.e., Z = 92 and A = 238).

Technical Note There are four types of radioactivity: alpha, beta, gamma, and neutron. Alpha and beta particles are physical particles, and so is the neutron. A gamma ray is a high-energy photon.

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Hazardous Materials Chemistry, Third Edition

Table 3-1

Radioactive Decay Process Toward Stability

Isotope

Emission

U-238

Alpha

Th-234

Beta and gamma

Pa-234

Beta and gamma

U-234

Alpha

Th-230

Alpha

Ra-226

Alpha

Rn-222

Alpha

Po-218

Alpha

Pb-214

Beta and gamma

Bi-214

Beta and gamma

Po-214

Alpha

Pb-210

Alpha and beta

Bi-210

Alpha

Po-210

Alpha

Pb-206

Stable

An element atom consists of protons, neutrons, and electrons. Atoms in their natural state try to achieve a level of stability. Table 3-1 . So why does radiation, the releasing of electrons and nuclei, exist? All elements have isotopes that have different numbers of neutrons and differing relationships to the number of protons in the nucleus. Hydrogen, for example, has three isotopes differing by the number of neutrons in the nucleus; it can have zero, one, or two neutrons in the nucleus. Depending on the isotope, the mass of the atom changes. Certain isotopes try to achieve a more stable state. In doing so, they can release an electron (beta particle) or a particle consisting of two neutrons and two protons (alpha particle), which are called helium nuclei, because helium has two protons and two neutrons when its electrons are stripped. In addition to the release of particles, energy is also released as a wave or package called photons or gamma rays. This whole process encompasses the terms radioactivity, radioactive decay, and spontaneous transmutation, which is the change of one chemical element into another by a nuclear reaction disintegration. The unstable nucleus releasing these items is said to be radioactive and the process is radioactive decay (see Table 3-1). By losing neutrons, protons, and electrons to achieve a stable state, a reduction of the atom’s components results in a different element. When identifying the activity of a radiological isotope, use the units of Curies (Ci) or Becquerels (Bq). Curies and Becquerels are a measure of activity, not radiation. Activity is the

measurement of the number of atoms transmuting per unit time. When describing a dose to a living organism, use sievert, Gray (Gy), roentgen equivalent man (REM), or radiation absorbed dose (RAD). One way to consider the difference between activity and dose is radiation, or the quantity of ionizing energy that is released by a radioactive material. This is the measurement of activity. Exposure is the amount of ionizing energy traveling through the air, referred to as a roentgen (R), and is also the radiation that you look at from a dose perspective.

Technical Note The unit of roentgen (R) is no longer recognized in 10 CFR Part 20 and is being phased out as an official unit for dose. However, it may be seen on radiation instrumentation. The absorbed dose is the amount of radiation that is absorbed by a person measured in RAD and Gy. Dose equivalent (or the effective dose) combines the amount of radiation absorbed and the medical effects on an individual measured in REM. Typically for emergency work, you will use 1 R = 1 RAD = 1 REM.

Alpha Particles The nucleus of a radioactive element has excessive repulsion in it. In order to reduce this pressure from within the nucleus, a helium nucleus, or alpha particle consisting of two neutrons and two protons, is released. This occurrence in effect reduces the atomic number by two and the mass number by four, and the element transforms or transmutates into another, usually radioactive, element. Alpha particles can travel only approximately 4 inches from their source. These particles can be stopped by a piece paper and, therefore, cannot penetrate even light clothing. The danger with alpha particles is ingestion. While alpha particles do not penetrate skin, if ingested they will damage internal organs quickly Figure 3-17 .

Alpha α N P P P

N

N

N N

N

N N

P

P

N

N P

Figure 3-17  An alpha particle. © Jones & Bartlett Learning.

Chapter 3 The Atom

69

Beta Particles

Gamma Radiation

Beta particles can be positively or negatively charged (referred to as an electron or positron) depending on the type of radiological emitter and the needs of the releasing and accepting atom. These particles travel at higher speeds than the alpha particle and are of smaller configuration (basically, they are the size of electrons). Most beta particles can travel about 1 to 20 feet from their source. Penetration can occur up to half an inch into the skin, but is blocked by dense material or a thin layer of metal. The beta particle is actually created when the neutron-to proton ratio is too great. One of the neutrons in the nucleus transforms itself into a proton and an electron. The proton is incorporated into the nucleus, and the electron is ejected with tremendous kinetic energy. This occurrence describes a negative beta particle release. With this type of beta release, the atomic number increases by one and the mass number remains essentially unchanged. The converse occurrence is the release of a positively charged electron or positron. Here the neutron-toproton ratio is too small, and a proton converts into a neutron and a positive electron. With the positive beta release, the mass number remains the same but the atomic number is decreased by one. A third process that may occur is when the unstable nucleus of the element that is releasing beta radiation captures an electron from the environment. The extra-nuclear electron is then incorporated in a proton, thus forming a neutron. The atomic number decreases by one and the mass number remains the same. This process occurs because of the neutron-to-proton ratio being too small Figure 3-18 .

Gamma radiation like X-rays, ultraviolet, infrared, and microwaves, gamma rays are electromagnetic energy Figure 3-19 . Ultraviolet and infrared radiation have long wavelengths as compared to X-rays and gamma radiation, which have shorter wavelengths. Gamma rays are photons, released from a nucleus of a high level of energy falling to a lower energy. The atomic number or mass of the atom remains unchanged. The energy is extremely strong and can penetrate most material. During a nuclear fission reaction, a neutron is sent into the nucleus of uranium-235, which captures the neutron and becomes U-236. This compound splits apart into two fission fragments: two or three neutrons and gamma rays. The energy that is released is in the form of kinetic energy and is used in an

e P

N

N P

N P

N

N N

Beta β

N

N P

Figure 3-18  A beta particle. © Jones & Bartlett Learning.

Sun High energy

Low energy

Cosmic rays

10

214

m

Gamma rays

10

Short wavelength (high frequency)

212

m

10

210

m

27

4 3 10 m (400 nm)

Figure 3-19  Electromagnetic energy spectra. © Jones & Bartlett Learning.

Ultraviolet

X-rays

28

Wavelength increases as frequency decreases

Visible

Frequency increases as wavelength decreases

Infrared

26

10 m

10 m

27

Microwaves Radar

24

10 m

27

6 3 10 m 5 3 10 m (500 nm) (600 nm) Visible spectrum

22

TV, FM AM Radio waves 0

10 m

10 m

27

7 3 10 m (700 nm)

2

10 m

Long radio waves 4

10 m Long wavelength (low frequency)

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Hazardous Materials Chemistry, Third Edition

Gamma γ P

N

N P

N P

N

N N

N

N P

Figure 3-20  Gamma radiation. © Jones & Bartlett Learning.

electrical reactor to increase the temperature of water to create steam to produce electricity by means of a turbine. However, in a nuclear age and with the threat of terrorism, governments are concerned about the growing level of nuclear waste. Fission fragments are produced in a fission reaction, and many are radioactive. These fragments are typically cesium-137, strontium-90, and iodine-131. Enriched uranium has a certain percentage of U-238 and U-235. Natural uranium is approximately 99.27 percent U-238; approximately 0.72 percent U-235; and, a trivial amount of U-234. The concentration of U-235 must be enriched in order to be used as a fuel in a nuclear reactor or as a weapon. Normal reactor fuel is typically enriched so that U-235 is in the 5–8 percent range, so the amount of U-238 is down to the 92–95 percent range. When U-235 is used in the compound, the material is spent but radioactive. “Spent” in terms of reactor fuel means the enrichment of U-235 has been “burned up” through fissioning and is no longer useful as a fuel. However, if U-238 captures a neutron, it is transformed into plutonium-239, which eventually decays into plutonium-239. Actually it becomes U-239 which eventually decays into plutonium-239. Spent nuclear fuel is loaded with usable amounts of all of these isotopes (U-238, Pu-239, Cs-137, Sr-90, I-131), which is why most countries recycle spent fuel. The problem is that the Pu-239 waste can be refined and the plutonium removed Figure 3-20 .

Understanding Radioactivity and Radiation Absorbed Dose Radioactive material is measured in units of activity and not by mass, weight, or volume. Activity is defined by the Nuclear Regulatory Commission (NRC) as the rate of disintegration (transformation) or decay of radioactive material. The units of activity are the Curie (Ci) and the Becquerel (Bq). One Ci of radioactive material is undergoing 37,000,000,000 disintegrations per second. One Bq, which is the International System of Units (SI) unit for activity, is the quantity of radioactive material in which one atom disintegrates, or is transformed per second. When a radioactive atom decays, the nucleus of the atom undergoes a transformation in order to reach a more stable energy state. It does this by emitting that excess energy in the form of particles

and electromagnetic waves. Alpha, beta, gamma, and neutron radiation are the most common forms, although there are a few other mechanisms by which the nucleus can change its energy state. Regardless of the mode of decay, the common factor is that energy is being emitted from the nucleus. For reference, radiation energy is given in units of electron volts. By definition, 1 electron volt (eV) is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electric potential difference of one volt. This is equal to 1.602 × 10−19 Joules of energy. The energy of alpha, beta, gamma, X-ray, and neutron radiation is typically given in units of kilo-electron volts (keV) or mega-electron volts (MeV). One keV equals 1000 eV, and 1 MeV equals 1,000,000 eV. Activity only describes the rate at which the material is decaying and not the total amount of energy being emitted as radiation. The potential risk from radiation exposure is dependent on how much of that energy is absorbed by something or someone. The unit used to measure the amount of radiation absorbed by an object or person is known as the RAD, or radiation absorbed dose. This is the amount of energy that radioactive sources deposit in materials through which they pass. The NRC defines the RAD as the amount of energy from any type of ionizing radiation, deposited in any medium (e.g., water, tissue, air). An absorbed dose of 1 RAD means that 1 gram of material absorbed 100 ergs of energy as a result of exposure to radiation. The related international system of unit is the Gray (Gy), where 1 Gy is equivalent to 100 RAD. As radiation moves through and interacts with a material, ionizing that material, it is gradually and continually losing its energy. This continues until the radiation has lost all its energy and no longer has enough energy to ionize. The probability of interaction is dependent upon the type of radiation, its energy, and the density and atomic number of the absorber. The term linear energy transfer (LET) refers to the energy imparted in a material per unit distance as ionizing radiation travels through that material. LET can vary depending on the type of radiation and charge of the particle involved. In general, alpha radiation has a much higher LET than beta radiation or gamma rays. Alpha radiation will therefore lose all of its energy in a relatively short distance and is unable to penetrate deep into any material. On the other hand, radiation with a low LET, such as beta and gamma, only loses a small amount of energy per interaction, allowing it to penetrate deeper into an absorbing material such as the human body. The biological effects of high LET radiation are in general much greater than those of low LET radiations with the same energy. This is because high LET radiation can deposit most of its energy within the volume of one cell of the body and the chance and amount of damage to the cell is therefore larger. The greatest risk to humans from radiation exposure is damage to the internal organs, bone marrow, gastrointestinal tract (GI), and brain cells. These are the three bodily systems associated with acute radiation syndrome. The bone marrow is within the bone, so the bone is actually providing some shielding. The same applies to the brain. The GI system is shielded in part by skin, muscle, and fat, and is even somewhat self-shielding because it wraps around itself.

Chapter 3 The Atom

As an external source, radiation must have enough energy and be capable of penetrating deep into the body through the natural human shielding (skin, muscle, bone) to be a risk to the internal organs. That is why gamma and neutron radiation, and not alpha and beta, are an external whole body radiation hazard Figure 3-21 . However, when radioactive material has been inhaled, ingested, or absorbed into the body, alpha radiation poses a greater risk of biological harm than beta or gamma radiation due to its high LET Figure 3-22 .

ALERT A situation described as ALARA (as low as is reasonably ­achievable) means that every reasonable effort has been taken to limit radiation exposure to below the dose limit.

mSv/h

International Nuclear Event Scale (1)

Alpha

Beta Gamma

milli-sieverts per hour

Level 7- Major Accident 100000 Radiation Level 6- Serious Poisoning Accident Level 4/5 8000 High Accident 10000 hemorrhaging, with Local/ dementia, death Wider in one day Consequences Level 3 Serious Incident (> 1000 mSv)

4000 Med nausea, infection lymph nodes Low 1000 itching, nausea Cancer risk: 1:20

Neutron

1000

100

Figure 3-21  Penetrating potential of radiation. © Jones & Bartlett Learning.

The rem, also known as the Roentgen equivalent man is one of the two standard units used to measure the dose equivalent or the effective dose of radiation. The effective dose takes into account the amount of energy from any type of ionizing radiation that is deposited in human tissue, that type of radiation’s ability to transfer its energy (LET), along with the potential medical effects of the given type of radiation. For beta and gamma radiation, the dose equivalent is the same as the absorbed dose. By contrast, the dose equivalent is larger than the absorbed dose for alpha and neutron radiation because these types of radiation are more damaging to the human body. Thus, the dose equivalent (in rems) is equal to the absorbed dose (in rads) multiplied by a quality factor for that type and energy of radiation. The related international system unit is the sievert (Sv), where 100 rem is equivalent to 1 Sv.

1:200

1. Time: Limit exposure; the shorter, the better. 2. Distance: Stay as far away as possible from the source; doubling the distance from the source, exposure is decreased by a factor of four (inverse square law).

World Events

Chernobyl core [6] Core explosion >300,000 mSv/h K-19 Submarine 8 deaths 1961, 54,000 mSv/h Atomic bomb [5] crater region, 30,000 mSv/h Louis Slotin Scientific accident, 1946 Manhattan Project Harry Daghlian Scientific accident, 1945 Manhattan Project Chernobyl workers average dose 170 mSv/h Radiation poisoning starts

10 Level 2 Incident (> 10 mSv) 1.0 Altitude [7] Level 1 Anomaly (> local background)

15 km High jet .01 mSv/h 10 km Jets .005 mSv/h

0.1

0.01

6.7 km Himalaya Mountains .0001 mSv/h 0.001

Radiation Hazard The particles or energy released from a radioactive isotope has the potential to interfere with biological systems. This disruptive action can impair cell function in the human body, resulting in a variety of illnesses. There are four basic safety factors in avoiding harm from radiation:

71

Level 0 Normal

2.0 km High cities (Denver) .00001 mSv/h

.0001

Radiation increases with altitude

Figure 3-22  International nuclear event scale. © Jones & Bartlett Learning.

International limit for nuclear workers 100 mSv/year = .01 mSv/h Geological radiation [8] Ramsar, Iran, Yiangling, China. Smoking 1 pack/day Most cities Household radon Three Mile Island Natural background 0.5 to 5 mSv/year

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Hazardous Materials Chemistry, Third Edition

3. Quantity: Limit the amount of the exposed radioactive material. 4. Shielding: Put almost anything between yourself and the source. The inverse square law describes a source of energy that spreads out in all directions equally. From a geometric standpoint, it is the intensity at any given radius from the source. In other words, energy that is twice as far from the source will spread over an area that is four times the original area, or reflect ¼ the intensity at distance. Use the following to identify the radiation at distance, where R is the RAD measurement and d is the distance: R/d2 = radiation at distance so a package at 20 feet is expressed as 100 R/(20 ft)2 = 0.25 R. This equation assumes that the first responder will walk up to the package and retrieve that information in order to make the calculation. However, a first responder can use this law to look at the radiation at a distance and reverse the logic to get the radiation at the package location without approaching it. The reverse inverse square law states that D2 × RD = RS where D is distance and S is source so at 20 feet, there is 0.25 R or (20 ft) × 0.25 R = 100 R. Many times hydrogen-laden products are also used as a shield for radiation protection. Hydrogen-laden material is best used for shielding neutron radiation because of the way neutrons interact with hydrogen atoms causing the neutron to lose its energy. 2

Protective Action Guides An essential reference for radiological emergency response is the U.S. Environmental Protection Agency’s PAG Manual: Protective Action Guides and Planning Guidance for Radiological Incidents (2017). This document is currently in draft format for interim use and public comment. It is an updated version of the 2013 publication, Manual of Protective Action Guides and Protective Actions for Nuclear Incidents (EPA-400/R-17/001, January 2017). The information and guidance contained in the PAG ­Manual is intended to address radiological incidents ranging from

Table 3-2

• The early phase addresses the beginning of a radiological incident when immediate protective actions are required. It is generally intended to cover the first four days of an event. • The intermediate phase covers the period after releases have been brought under control but not necessarily eliminated. This phase may last from weeks to months. • The late phase covers the recovery period and actions necessary to reduce radiation levels in the environment to acceptable levels. This phase may last from months to years. For the purpose of emergency response planning, the early phase PAG Manual recommendations are the most relevant to the majority of radiological events that may be encountered. These would include such things as transportation accidents, fires at facilities that use and produce radioactive material, and lost or stolen radioactive sources. Response to any radiological incident involves the potential exposure to radiation and contamination hazards. The PAG Manual provides recommendations for both, with the expectation that the Incident Commander should make every effort to maintain ALARA. Response worker guidelines for radiation exposure assume a “once-in-a-lifetime” dose and that future exposures would be substantially lower than that received during a serious radiological event. The dose includes exposure from external sources and internal contamination. Table 3-2 provides guidelines for response workers during the early phase. These guidance values, based on the urgency of the situation and knowledge of the risks involved, are intended to minimize potential long-term risk to the responder. However, they should not be interpreted as a fixed limit.

Early Response Phase Guidelines

Guidelines

Activity

Condition

5 REM (50 mSv)

All occupational exposures

All reasonably achievable actions have been taken to minimize dose.

10 REM (100 mSv)

Protecting valuable property necessary for public welfare (e.g., a power plant)

Exceeding 5 REM (50 mSv), unavoidable and all appropriate actions taken to reduce dose. Monitoring available to project or measure dose.

25 REM (250 mSv)b

Lifesaving or protection of large populations

Exceeding 5 REM (50 mSv), unavoidable and all appropriate actions taken to reduce dose. Monitoring available to project or measure dose.

a

a

transportation to nuclear power plants to improvised nuclear devices. The protective actions recommended are intended to address the potential impact resulting from significant releases of radioactive material into the environment. It is important to understand that the PAG Manual is a guidance document only. It is not legally binding nor does it supersede any environmental laws. The PAG Manual is divided into three phases: early, intermediate, and late.

For potential doses >5 REM (50 mSv), medical monitoring programs should be considered. In the case of a very large incident, such as an improvised nuclear device (IND), incident commanders may need to consider raising the property and lifesaving response worker guidelines to prevent further loss of life and massive spread of destruction. b

Chapter 3 The Atom

Stay Time Charts

So, by simply reworking the equation, stay time can be calculated:

It is important to understand that radiation dose is a function of time. The longer the time spent in the radiation field, the greater the dose to the individual.

Stay Time = Allowable Dose ÷ Dose Rate Stay time charts can be used to help responders plan their response in areas with elevated radiation levels. The allowable dose used in the calculation can be the values recommended in the PAG Manual, predetermined jurisdictional values, situational needs, or restricted levels based on a responder’s previously acquired dose Figure 3-23 . The variable in this equation is the dose rate on scene. This can be determined through direct measurement or estimated using computer modeling or source term information from shipping papers, facility personnel, and radiation specialist resources.

Dose = Dose Rate × Time Personnel must limit their time in a radiation hazard area in order to keep exposures ALARA and ensure they do not exceed their established dose limits. If personnel are available, a rotating team approach can be used to keep individual radiation exposures to a minimum. The term “stay time” refers to the amount of time it would take a person to reach a predetermined allowable dose in a known dose rate field. Allowable Dose = Dose Rate × Stay Time

T

Exposure Rate*

O

T

A

L

D

O

S

E

100 mrem

1 rem

5 rem

10 rem

25 rem

50 rem

100 rem

125 rem

150 rem

1 mR/h

4 day

6 wk

7 mo

14 mo

2.8 yr

5.7 yr

11.4 yr

14.3 yr

17.1 yr

2 mR/h

50 h

3 wk

3.5 mo

7 mo

1.4 yr

2.9 yr

5.7 yr

7.1 yr

8.6 yr

5 mR/h

20 h

8.3 day

6 wk

2.8 mo

7 mo

1.2 yr

2.3 yr

2.8 yr

3.4 yr

10 mR/h

10 h

4 day

3 wk

6 wk

3.5 mo

6.9 mo

14 mo

1.4 yr

1.7 yr

25 mR/h

4h

40 h

8.3 day

16.6 day

6 wk

2.8 mo

5.6 mo

7 mo

8.3 mo

50 mR/h

2h

20 h

4 day

8.3 day

3 wk

6.0 wk

2.8 mo

3.5 mo

4.2 mo

100 mR/h

1h

10 h

50 h

4 day

10 day

20.8 d

6 wk

7.5 wk

2 mo

200 mR/h

30 min

5h

25 h

50 h

5 day

10.4 d

3 wk

3.7 mo

1 mo

500 mR/h

12 min

2h

10 h

20 h

50 h

4.1 d

8.3 day

10.4 day

12.5 day

1 R/h

6 min

1h

5h

10 h

25 h

2.1 d

4 day

5.2 day

6.2 day

2 R/h

3 min

30 min

2.5 h

5h

12.5 h

1.0 d

50 h

2.6 day

3 day

5 R/h

72 sec

12 min

1h

2h

5h

10 h

20 h

25 h

30 h

10 R/h

36 sec

6 min

30 min

1h

2.5 h

5h

10 h

12.5 h

15 h

25 R/h

14.4 sec

2.4 min

12 min

24 min

1h

2h

4h

5h

6h

50 R/h

7.2 sec

72 sec

6 min

12 min

30 min

1h

2h

2.5 h

3h

100 R/h

3.6 sec

36 sec

3 min

6 min

15 min

30 min

60 min

75 min

1.5 h

200 R/h

1.8 sec

18 sec

90 sec

3 min

7.5 min

15 min

30 min

37.5 min

45 min

Figure 3-23  Stay time charts. Data from ASTM E2601. © Jones & Bartlett Learning.

73

Case Study Answers 1. What has happened? This incident brings to light several issues that should be addressed on many levels. It is beyond the scope of this text to comment or suggest on local, state, or federal level actions that should have been in place prior, during, and after the event. Several reports on this have been written and are in a better place for these suggestions. Both local and state emergency management along with federal resources need to be involved with this type of incident. On the responder level, it is vitally important to establish whether you have a hazardous environment. In a later chapter, illicit use of chemicals and the measurement instrumentation, which the first response community has in place at a variety of levels throughout the country, will be discussed. It is truly up to the first response personnel to start to look at incidents in a global stance and not get too focused on the direct facts, but rather look around and see what the whole incident is presenting. To answer the question directly, this incident highlights how easily an exposure can occur. It shows us that a simple event can have far-reaching consequences. On the surface, you see that a family has been exposed, resulting in death; however, you also have friends, neighbors, neighborhoods, community, and the city at large with some level of effects. You can further explore the environmental ramifications, both short term and long term, within this community, all of which need to be addressed by the hazmat team response.

2. What can you do to change the outcome? Recognition is the first step; once you see the potential issues, then you can act. In this case, why was a group of individuals getting sick? The 6-year-old daughter of one of the salvagers became critically ill and was confined to an isolation room where she was left alone because the hospital staff was afraid to touch her, and she died a month later. The wife, who discovered that an illness was surrounding the salvaged capsule, also died a month later; however, her actions of recognition probably saved many lives within the local community. The two salvage men also died a month later; in each of these cases, it was estimated that a dose between 450 and 600 REM was encountered by these individuals. In total, 250 people become contaminated with radioactive residue found on their skin. A total of 130,000 people overwhelmed the medical system.

In other words, understanding your response area and having a plan for a wide area response is essential in any Comprehensive Emergency Management Plan (CEMP). This plan must incorporate automatic response, mutual aid, regional aid, and in-state response leading toward the federal response system.

3. What level of radiation should you be concerned with? As discussed previously, the levels these individuals were exposed to were extremely high. If you look at the stay time charts and estimate the activity of the Cs-137, you can see that the dose rate had exceeded the normal levels of radiation. The individuals did not know at first they are been irradiated, and it is for this reason, as you look at chemicals from a response perspective, you rule in or rule out radiation as a threat first. Protective action guidelines (PAG) should be adhered to at all radioactive incidents. These guidelines should be followed up with a health physicist’s input, with very comprehensive action planning. Some suggestions fir the first three action levels have been 5 REM, 10 REM, and 25 REM; the latter value being the high end of the spectrum for a one-time rescue, with the absolute top dose being 50 REM for a catastrophic event. Remember, these levels are when you approach the incident. Once you spend time within the environment and return to the safety of the cold zone, at a minimum, you have doubled your exposure.

4. What event level is this? Using the scale introduced at the beginning of this chapter, this event become a level 5 event. As you can see, a seemingly simple event can have large impact to both the social structure of a community and the medical system contained within and external to it. In any event, recognition of the event along with identification of such an event is critical in order to get ahead of the incident. Here, several indicators were ignored. As an example, one of the salvage men did go to the hospital early in the event, complaining of a burn-like area on his hands. He was sent home to get some rest. The key is to look at chemistry from an investigative standpoint. The principles that you are using within this text are directly applicable to the street. Chemical and physical properties along with air monitoring and detection systems can lead you down the correct path. The process that you will start to develop is an investigatory method through the use of deductive reasoning, or what is commonly called the scientific method.

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WRAP-UP In Summary • Chemistry is the science of matter, energy, their reactions and interactions. Matter is anything that occupies space. It may be a solid, liquid, or gas. It also may be a pure substance or a mixture. Pure substances may be compounds or elements. Mixtures are physical blends of elements, compounds, or both. Elements are materials that cannot be broken down into simpler form by normal means and still retain the properties of that particular element. • Atoms consist of protons, found in the nucleus of the atom with an atomic weight of 1 and electrical charge of +1. The atom will possess the same number of protons within a given element. Neutrons with no electrical charge are also found in the nucleus of the atom. The atomic weight of the neutrons is 1 and the number will vary within the nucleus. Electrons are in the shell surrounding the nucleus and essentially have no weight; however, they have an electrical charge of −1. Chemical behavior is ultimately determined by the number of electrons in the outer shell. • The atomic number indicates the number of protons in the nucleus and is equal to the number of electrons. The elements on the periodic table are listed by increasing atomic number. The configuration of the chart results in repetition of certain common properties between the elements within groups. The atomic weight varies; however, the number of protons within the nucleus remains the same. The weight variations are due to the number of neutrons and the average of the isotopes that occur. • The periodic table is the basic tool for chemical identification and the potential hazards that may arise. Each box within the table represents an element. Each element is represented by a symbol. The position within the table indicates the physical and chemical properties of an element. As you move down the table, the elements become larger. Moving across the table from left to right, the elements become smaller and more electronegative.

• Nature does not like anything to be in an unstable state; there is a continual desire for the elements to achieve a state of stability. In the case of atoms, this means the outer shell of an element must have the appropriate number of electrons. There are two ways that an atom can achieve this state of stability. One is by forming molecules whereby the whole structure will satisfy the rule of stability. The other is by the element or group of elements (molecule) forming an ion. • Ions may also be formed by a group that has collectively gained or lost electrons. The group will also have a charge equal to the number of electrons gained or lost. Negatively charged ions are called anions and positively charged ions are called cations. This concept is true whether or not the ion was formed by a single atom or a group. Once ions are bonded, the resulting compound must achieve an electrically neutral environment. • Chemical and physical properties allow us to understand the basic chemistry that a substance possesses. Knowledge of these properties enables us to use monitoring equipment, make intelligent decisions, and establish strategic priorities. By using your knowledge of chemical and physical properties, the hazards and mitigation techniques have a basis in the sciences. • There are four types of radioactivity: alpha, beta, gamma, and neutron. Alpha and beta particles are physical particles; a gamma ray is a high-energy photon, or light package, released when an atom “falls” from a high level of energy to a lower level. • It is important to understand that radiation dose is a function of time. The longer the time spent in the radiation field, the greater the dose to the individual. ▪▪ Dose = Dose Rate × Time • PAGS for emergency use are 5 REM (50 mSv), 10 REM (100 mSv)a, 25 REM (250 mSv)b.

Key Terms “A” number  The mass of an atom results from the number of neutrons and protons; the mass number. actinides  See the inner transition metals. ALARA (as low as reasonably achievable)  Making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. alkali metals  Group 1: The elements that are in the first column or group to the left on the periodic table: lithium, sodium, potassium, rubidium, cesium, and francium. alkaline earth metals  Group 2: The elements that are in the second column or group from the left on the periodic

table: beryllium, magnesium, calcium, strontium, barium, and radium. alpha particle  The radiation particle consisting of two neutrons and two protons that is emitted from certain radioisotope decay. aluminum family  Group 13: A group of elements on the periodic table represented by boron, aluminum, gallium, indium, and thallium. anion  Negatively charged ions. atomic number  The number of protons in the nucleus of an atom; “Z” number.

WRAP-UP atomic weight  Atomic weight is the weighted average of all the isotopes of an element. Becquerels (Bq)  The unit of measurement for radioactivity equivalent to one disintegration of a nucleus per second; it is the activity of the atom. beta particle  An electron (negatively charged) or positron (positively charged) emitted from a radioactive isotope during beta decay. cation  Positively charged ions. covalent bond  The chemical bond that forms as a result of atoms sharing electrons. Curies (Ci)  A unit of measurement of radioactivity as compared to 1 g of radium whereby 1 Ci = 3.700 × 1010 decays per second. electronegativity  A measure of how strongly an atom holds on to its electrons or attracts electrons from other atoms when part of a chemical bond. electrons  Negatively charged fundamental particles located outside the nucleus of an atom. gamma radiation  Electromagnetic radiation of energy emitted from radioisotopes. germanium family  Group 14: A group of elements on the periodic table represented by carbon, silicon, germanium, tin, and lead. Gray (Gy)  The unit of an absorbed dose of radiation. groups  Chemicals arranged in vertical columns on the periodic table containing families of elements. halogens  Group 17: A group of elements on the periodic table consisting of fluorine, chlorine, bromine, iodine, and astatine. inner transition metals  A region on the periodic table underneath the transitional metals that have two main groups: lanthanides (rare earth metals) and actinides. ionic bond  The attraction of oppositely charged particles (i.e., the chemical bond that forms between cation and anion). ionization energy  The amount of energy required to remove an electron from an atom. isotopes  Forms of an element that have the same number of protons but a different number of neutrons. lanthanides  See inner transition metals; also known as the rare earth metal. mass number  The total number of neutrons and protons in the nucleus of an atom; “A” number. metalloids  A region of the periodic table that includes the elements between the nonmetals and the right-side representative metals: boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te).

neutrons  Fundamental particles without electrical charge that are part of the nucleus of an atom. nitrogen family  Group 15: A group of elements on the periodic table consisting of nitrogen, phosphorous, arsenic, antimony, and bismuth. noble gases  Group 18: A group of elements on the periodic table made up of helium, neon, argon, krypton, xenon, and radon; sometimes referred to as the inert gases. nucleus  The center of an atom, containing the protons and neutrons. orbitals  The areas of high statistical probability in which an electron will be found. period  Each horizontal row on the periodic chart. periodic table  A general framework of the elements that organizes all elements based on similarities in chemical behavior. protons  Positively charged subatomic particles that are part of the nucleus of an atom. pyrophoric  Liable to ignite spontaneously on exposure to air. radiation  The mechanism by which energy is transferred between two materials that are not in contact through the outward movement of electromagnetic waves. radiation absorbed dose (RAD)  A unit slightly greater than 1 roentgen, which is used to measure dosage. radioactive decay  The process by which an unstable nucleus releases particles and/or energy in order to become stable; sometimes referred to as radioactivity or spontaneous transmutation. rare earth metals  See inner transition metals; also known as lanthanides. representative metals  A region of the periodic table that includes the first two columns or groups and seven elements from groups 13 and 14. roentgen (R)  The measurement of radioactivity for gamma radiation; it is the amount of ionization per cubic centimeter of air; it is a measurement of exposure and represents the amount of gamma radiation that produces two billion ion parts in dry air. roentgen equivalent man (REM)  A measurement of biological effect; it represents the amount of absorbed radiation of any type that produces the same effect on the human body as 1 roentgen of gamma radiation. shell model  A model used to predict the chemical reactivity of the elements; it treats the atoms as having “shells” of electrons located at increasing distances away from the nucleus. sievert  A dose equivalent equal to 100 REM. transition metals  A region of the periodic table that includes the groups in the lower portion of the main chart identified by the numbers 3–12.

Chapter 3 The Atom

transmutation  The change of one chemical element into another by a nuclear reaction disintegration. valence electrons  The electrons in the outermost shell of an atom.

valence shell  In the outermost shell of the atom. “Z” number  The number of protons determines the atomic number; atomic number.

Review Questions Before working on the review questions, memorize the following chemical symbols. Having them committed to memory will help with your research of hazardous materials at the incident scene. Hydrogen

H

Helium

He

Boron

B

Carbon

C

Fluorine

F

Neon

Ne

Aluminum

Al

Silicon

Si

Chlorine

Cl

Argon

Ar

Scandium

Sc

Titanium

Ti

Manganese

Mn

Iron

Fe

Zinc

Zn

Arsenic

As

Silver

Ag

Cadmium

Cd

Iodine

I

Xenon

Xe

Platinum

Pt

Gold

Au

Lithium

Li

Beryllium

Be

Nitrogen

N

Oxygen

O

Sodium

Na

Magnesium

Mg

Phosphorus

P

Sulfur

S

Potassium

K

Calcium

Ca

Vanadium

V

Chromium

Cr

Nickel

Ni

Copper

Cu

Bromine

Br

Krypton

Kr

Tin

Sn

Antimony

Sb

Cesium

Cs

Barium

Ba

Mercury

Hg

Lead

Pb

1. How many electrons are in the outer shell in elements in group 1? a. 1 b. 2 c. 3 d. 4 2. How many electrons can group 1 elements lose? a. 1 b. 2 c. 3 d. 4

3. How many electrons are in the outer shell of elements in group 2? a. 1 b. 2 c. 3 d. 4 4. How many electrons can group 2 elements lose? a. 1 b. 2 c. 3 d. 4 e. 4 5. How many electrons can the nonmetals in group 15 accept? a. 3 b. 4 c. 5 d. 6 6. How many electrons can the nonmetals in group 16 accept? a. 2 b. 3 c. 4 d. 5 7. How many electrons can group 17 elements accept? a. 1 b. 2 c. 3 d. 4 8. What elements do the following abbreviations represent? a. Li b. Na c. K d. Rb e. Cs f. Fr 9. What is the name for the first group on the periodic table? a. Alkali metals b. Alkaline earth metals c. Transition metals d. Nitrogen family

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WRAP-UP 10. What is the name for the second group on the periodic table? a. Alkali metals b. Alkaline earth metals c. Transition metals d. Nitrogen family

16. What elements do the following abbreviations represent? a. O b. S c. Se d. Te e. Po

11. What elements do the following abbreviations represent? a. Be b. Mg c. Ca d. Sr e. Ba f. Ra

17. What is the name given for group 17? a. Alkali metals b. Alkaline earth metals c. Transition metals d. Halogens

12. What elements do the following abbreviations represent? a. Hg b. Cd c. Cr d. Tl e. Zr f. Zn 13. What elements do the following abbreviations represent? a. B b. Al c. Ga d. In e. Ti 14. What elements do the following abbreviations represent? a. C b. Si c. Ge d. Sn e. Pb 15. What elements do the following abbreviations represent? a. N b. P c. As d. Sb e. Bi

18. What elements do the following abbreviations represent? a. F b. Cl c. Br d. I e. At 19. Which of the following is a true statement? a. Alkali earth metals do not react with water. b. Nobel gases react violently with water. c. All halogens are harmful. d. All the above. 20. How many electrons can the halogen-group elements accept? a. 7 b. 5 c. 3 d. 1 21. Which is the most electronegative element of the following choices? a. O b. Br c. F d. N 22. What is the name given for group 18? a. Alkali metals b. Alkaline earth metals c. Noble gases d. Halogens 23. What elements do the following abbreviations represent? a. He b. Ne c. Ar d. Kr e. Xe

Chapter 3 The Atom

Problem Set Answers Problem Set 3-1 1. For the first 12 elements on the periodic table, determine the number of shells and electrons within each shell. 1. H  ; Hydrogen: 1 electron = 1 shell 2. H  e; Helium: 2 electrons = 1 shell 3. L  i; Lithium: 3 electrons = 2 shells 4. B  e; Beryllium: 4 electrons = 2 shells 5. B  ; Boron: 5 electrons = 2 shells 6. C  ; Carbon: 6 electrons = 2 shells 7. N  ; Nitrogen: 7 electrons = 2 shells 8. O  ; Oxygen: 8 electrons = 2 shells 9. F  ; Fluorine: 9 electrons = 2 shells 10. N  e; Neon: 10 electrons = 2 shells 11. N  a; Sodium: 11 electrons = 3 shells 12. M  g; Magnesium: 12 electrons = 3 shells

Problem Set 3-2 1. Given a “number,” determine the element and the other “numbers” that are associated with it.

1s1 1s2 1s2 2s1 1s2 2s2 1s2 2s2 2p1 1s2 2s2 2p2 1s2 2s2 2p3 2

2

4

1s 2s 2p

1s2 2s2 2p5 1s2 2s2 2p6 1s2 2s2 2p63s1 1s2 2s2 2p63s2

Name

Atomic number

Mass Number Number of Protons

Number of Electrons

Oxygen

 8

16

 8

 8

Calcium

20

40

20

20

Sodium

11

22

11

11

Fluorine

 9

19

10

 9

Aluminum

13

27

14

13

Rubidium

37

85

48

37

Chlorine

17

35

18

17

Problem Set 3-3 1. From the table in Problem Set 3-2 and using your understanding of ionization, which element is the most electronegative? Fluorine

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CHAPTER © dra_schwartz/Getty Images.

4

Bonding LEARNING OBJECTIVES Upon completion of this chapter, you should be able to: • Anticipate bonding behavior and molecular geometry of molecules that will later be useful for predicting chemical and physical properties. • Explain the theory of ionic and covalent bonding. • Define electronegativity and identify its usefulness in bonding theory. • Construct Lewis structures and describe their application. • Explain valence electrons. • Describe resonance structures. • Explain how to predict molecular geometry.

NFPA Citations and Competencies Citation or Competency Heading

NFPA 472 Reference

Hazard evaluation

11.3.3, A.3.3.49, A.7.1.2.2(3), A.8.1.2.2(2)(d), A.9.3.1.2.2(2)(e), A.11.3.3(3)

Hazard prediction

7.2.5, 10.1.2.2

Estimating harm

5.2.3, 5.2.4, 7.2.5, 8.2.2, A.5.2.4, A.7.2.5.6

Case Study On November 17, 2003, in Glendale, Arizona, a chlorine release occurred from a batch scrubber at a chlorine repacking facility, causing an evacuation of about a 1.5 square mile area. The release lasted about 6 hours, causing several injuries but no fatalities. The process was to remove chlorine from a railcar and place it into a tank truck for over-the-road hauling. Courtesy of Bill Hand. The chlorine is passed through a system by compressed air piped into the rail car pushing the liquid chlorine through the system and into the tank car. Chlorine vapors are released within the tank car during the process and these vapors are placed through a closed system to scrub the vapor. The scrubbing unit is a system that cleans the air/vapor space and produces bleach, which is in turn used as a commodity. In the scrubber, the chlorine reacts with sodium hydroxide solution at a controlled temperature. The reaction removes the chlorine from the incoming vapor and produces sodium hypochlorite and common table salt. Depletion of the scrubber’s sodium hydroxide stops the ability of the scrubber to remove chlorine vapors from the incoming vapor line and thus chlorine vapor is then purged from the vessel so as to not to create an over pressure. During the process, the sodium hydroxide is monitored so that the transfer of chlorine can be stopped and additional sodium hydroxide can be added if necessary (or changed from one vessel to another). Each scrubber has a capacity of 4000 gallons, with each total unit having a primary container and a secondary backup scrubber. The event that started the release of chlorine began at about 10:00 am that day, resulting in chlorine release by about 1:30 pm that same day. The initial air monitoring around the scrubber was about 20–35 ppm. During the event, the scrubber “burped,” releasing more chlorine until the situation was contained. Evacuation of the area lasted for more than 4 hours, while responders and facility workers contained the release and managed the scrubbing unit involved. Using the principles set forth in this section, answer the following questions: 1. What has happened? 2. What will or could happen? 3. What can you change, now and 30 minutes from now?

Introduction You’ve learned that atoms are comprised of protons, neutrons, and electrons, and that electrons are the particles responsible for the chemical bonding and the typical behaviors of the elements. This chapter will explore how bonding works, which will later provide the clues necessary for identification. Although nomenclature will be discussed in greater detail in later chapters, a first responder should be able to correctly identify between certain types of compounds, using only a name or a formula. Recall that compounds are substances composed of two or more elements in a fixed proportion and chemically bonded. Understanding the compound type is important when selecting the appropriate detection equipment needed at an incident. Understanding bonding and consequences of it can be directly related to Benner’s model, as well as how it corresponds with offensive, defensive, or non-intervention approaches at the scene. Understanding bonding is an important part of the risk assessment puzzle, which will be addressed further in C ­ hapter 12, Risk-Based Response.

Chemical Bonding Valence Electrons and Bonding Previously you learned about the electronic structure of the atoms. You also learned to recognize how many total electrons

and valence electrons exist in a particular atom by locating that element on the periodic table. Understanding the electronic structure of atoms allows us to predict the likely chemistry of many elements. This is because with the exception of nuclear chemistry, valence electrons are responsible for the chemistry of the atoms and are the electrons involved in bonding. Recall that valence electrons are those electrons in the “outer­ most shell” of an atom. (More precisely, the valence electrons are those that occupy orbitals with the highest energies and when orbitals are close in energy to each other, chemists group them together and call that a shell.) In general, atoms react in such a way that they achieve a more stable electronic structure. The most stable electronic structure atoms can obtain is a completely filled valence shell, just like the noble gas atoms. More often than not, atoms react in a way to achieve a full valence shell and therefore a similar electronic structure to one of the noble gases. The only elements that are stable as individual atoms are the noble gases. Each noble gas has a total number of electrons that corresponds to having completely full shells, even their valence shell. Other atoms react in such a way to achieve a full valence shell. To obtain a full valence shell, atoms will lose valence electrons, gain additional valence electrons, or share valence electrons to become part of a covalent chemical bond. In compounds, there are two general types of chemical bonds: ionic and covalent. Ionic bonds are the result of electron transfer from a species that becomes more stable when electrons are lost to a species that becomes more stable when electrons are gained.

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Covalent bonds are the result of electron sharing between two atoms that each require additional electrons to complete their valence shell.

The Ionic Bond The ionic bond is the electrostatic attraction between ions of opposite charge, a positive cation and a negative anion. Because ionic bonds are formed between atoms that become stable by losing electrons and atoms that become stable by gaining electrons, usually ionic compounds contain a metal and a nonmetal. In an ionic compound, the metal is a positively charged cation and the nonmetal is a negatively charged anion. Remember this rule of thumb: metals lose electrons, and nonmetals gain or share electrons. Let us use as an example a very common ionic compound, sodium chloride, NaCl. After locating sodium, Na, on the periodic table, you will notice immediately that it is in group 1 and contains one valence electron. The easiest way for ­sodium to achieve a full outermost shell is to lose that ­valence electron and have the same number of electrons as neon. After locating chlorine on the periodic table, you will notice that it is in group 17. One way that it can achieve a full outermost shell is to gain an electron to have the same number of electrons as argon. When sodium metal reacts with chlorine gas, electron transfer occurs. Sodium will lose its valence electron and chlorine will gain it. After electron transfer occurs, sodium still retains its 11 protons, but because it lost one electron, now only has 10 electrons. Because sodium now contains 11 protons and 10 electrons, it will have an overall positive charge of +1. Chlorine, after gaining an electron now has 17 protons, but 18 electrons, resulting in an overall charge of −1. Because opposite charges attract, sodium and chlorine are attracted to each other. That resulting bond is known as an ionic bond. Because each charge has a magnitude of 1, the ratio when they combine is 1:1 Figure 4-1 .

Ionic boning

Na

-

- -

CI

-

- -

Na

-

CI

-

When water is dripped onto calcium carbide, it produces a regulated amount of acetylene gas. Calcium carbide has a structure that is a bit confusing. It is a calcium ion in association with two triple-bonded carbons: Ca++ –C ≡ C–. Hence the formula CaC2. It was used as a fuel inside old miner’s lamps Figure 4-2 .

Figure 4-2  An antique calcium carbide miner’s lamp. © Jobjansweijer/Shutterstock, Inc.

Ionic compounds are not just compounds between metals cations and nonmetal anions. Ionic compounds are compounds formed by the attraction between any cation and anion. Some cations and anions contain more than one atom. These are referred to as the polyatomic ions. The atoms that comprise polyatomic ions are covalently bonded to each other, but then have either fewer or more electrons than the number of protons, resulting in an overall charge. There is only one very common polyatomic cation: ammonium, or NH4+. Because the cation in an ionic compound is either a metal or ammonium, it is often easiest to recognize an ionic compound by looking for a metal or ammonium. If you find either, you know that the compound is ionic.

-

- -

+

Technical Note

-

- Figure 4-1  An ionic bond.

Because ionic compounds are the result of the relatively strong electrostatic attraction between oppositely charged ions, they are solids with high melting points.

Technical Note There are other polyatomic cations besides ammonium. Most of them are formed as a result of adding a proton to an amine. For example, if dimethylamine is protonated in an acid-base reaction, the result is dimethylammonium. Dimethylammonium may then bind to an anion to form an ionic compound. Many polyatomic cations, if not ammonium, have “ammonium” in their name.

There are many polyatomic anions. Polyatomic anions are comprised of more than one atom covalently bonded together but have additional electrons than protons, resulting in an overall negative charge. The magnitude of the overall charge depends

Chapter 4 Bonding

83

Common Polyatomic Ions 1 - charge Formula

2 - charge Name

Formula

3 - charge

Name

Formula

Name

H2PO4—

Dihydrogen phosphate

HPO42—

Hydrogen phosphate

PO33—

Phosphite

C2H3O2—

Acetate

C2O42—

Oxalate

PO43—

Phosphate

HSO3

Hydrogen sulfite

SO32

Sulfite

HSO4—

Hydrogen sulfate

SO42—

Sulfate

HCO3

Hydrogen carbonate

CO32

Carbonate

NO2—

Nitrite

CrO42—

Chromate

NO3—

Nitrate

Cr2O72—

Dichromate

CN—

Cyanide

SiO32—

Silicate

OH

Hydroxide

—

—

—

MnO4—

Permanganate

ClO

Hypochlorite

—

ClO2—

Chlorite

ClO3

Chlorate

—

ClO4—

—

—

1 + charge Formula

Name

NH4+

Ammonium

Perchlorate

Figure 4-3  Common polyatomic ions.

on the number of additional electrons. It is often necessary to simply memorize the names, formulas, and overall charges of common polyatomic anions. The common polyatomic ions are organized by charge in Figure 4-3 . When predicting the formula for an ionic compound, it is important to recognize that all compounds are electrically neutral. That means that cations and anions combine in the ratio that results in an overall charge of zero. When determining the formula for any ionic compound, one would perform the following steps: Step 1. Recognize the compound as ionic (it contains either a metal or a form of ammonium). Step 2. Identify the charges of the cation and the anion. Step 3. Identify the ratio that results in an electrically neutral compound. To determine the chemical formula for calcium chloride, for example, one would first recognize that since calcium is in group 2, it would be a cation with a charge of +2. Since chlorine is in group 17, it would be an ion with a charge of −1. Because you need two species that have a charge of −1 to balance out 1 species with a charge of +2, the formula for calcium chloride is CaCl2. For ionic compounds involving polyatomic anions, it is necessary to learn the formulas and charges of the polyatomic ions. To determine the formula for sodium carbonate, you would first

recognize the compound as ionic because it contains sodium, a metal. You would identify the charge of sodium as +1 since it is in group 1 of the periodic table. Then, to figure out the rest of the formula, you would have to know (or look up) that the identity of carbonate is CO32−. Once the identity of carbonate is known, you would know that two sodium ions with their +1 charge balance out the carbonate with its −2 charge.

ALERT Ionic compounds are often referred to as salts. Be aware that salts: • • • • •

Dissolve in water Conduct electricity when dissolved in water Can be toxic Are solids with high melting points Do not burn under normal conditions.

The Covalent Bond The covalent bond is the result of two atoms sharing electrons. Because the atoms that are likely to share electron would only need a few more to achieve a full valence shell, covalent bonds are formed between nonmetals.

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Hazardous Materials Chemistry, Third Edition

As an example, let us consider those elements that exist as molecules that contain two atoms. Chlorine gas is an example of that. Based on its position on the periodic table, you can tell that the valence shell of chlorine contains one fewer electron than is needed to be full. Chlorine can achieve stability in two ways. It can gain an electron, like it does when it reacts with sodium; in this case, it would become negatively charged and participate in an ionic bond. The other way for chlorine to achieve stability is by sharing an electron. In the case of elemental chlorine, each chlorine atom only needs one electron for stability. Therefore, each atom will share one electron with another atom. The result is a covalent bond where the bond contains a pair of electrons, one electron each contributed from the two atoms Figure 4-4 .

More often than not, electrons being shared in a covalent bond are not distributed evenly. When the atoms involved in a covalent bond are different from each other, usually one atom attracts the electrons more strongly than the other. When this is the case, the electrons are closer to the more electronegative atom, and the bond is said to be polar. Recall from Chapter 3, The Atom, electronegativities increase going across a row (­ excluding the noble gases) and decrease going down a column of the periodic table. In general, you can tell which atom would more strongly attract the electrons in a covalent bond by locating it on the periodic table. Fluorine is the most electronegative atom. As you get further away from fluorine, atoms will get less electronegative Figure 4-6 .

Technical Note CI

CI

chlorine atoms

CI

CI

chlorine molecule

Figure 4-4  A covalent bond. © Jones & Bartlett Learning.

A molecule is the smallest unit of some substances that retains all the properties of that substance and is composed of two or more atoms. The elements that exist and have two atoms per molecule are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. The molecules of oxygen and nitrogen contain a double and triple covalent bond, respectively. Notice from their positions on the periodic table that oxygen needs two valence electrons and nitrogen needs three valence electrons. Therefore, in a molecule of oxygen, each oxygen will share two electrons to form a double bond and in a nitrogen molecule, each atom will share three electrons to from a triple bond Figure 4-5 . The second structure in Figure 4-4 is a Lewis structure. In a Lewis structure, bonding electron pairs are represented with lines connecting the atoms.

O

O

double bond

N

N

triple bond

Figure 4-5  Double and triple covalent bonds.

When electrons are shared, they are only sometimes shared evenly. This would be the case with chlorine gas. Because each individual atom that is participating in the bond has the same relative attraction for electrons as the other, the electrons are distributed evenly between the two atoms. When the electrons are distributed evenly, the covalent bond is said to be nonpolar. A bond between two atoms that have the same attraction to the electrons will be nonpolar. This will always be the case when the two atoms involved in the bond are the same.

As you move through the families on the periodic table starting from group 1, you will see that main group metals form strong ionic bonds with nonmetals and the nonmetals form covalent bonds with each other. Remember, it is the covalent bonds that infrared and Raman technologies can “see.”

In general, the further apart two atoms are from each other on the periodic table, the more polar the covalent bond between them would be. This is because the difference in electronegativity of the atoms involved in the bond tends to be wider when the atoms are further apart from each other on the periodic table. In fact, you can consider the ionic bond as being the extreme polar bond where an electron is so much more attracted to one atom over the other that it actually transfers from one atom to the other. This is the case with sodium chloride Figure 4-7 . The affinity chlorine has to electrons is so much greater than that of sodium, that the lone valence electron of sodium actually is transferred to chlorine, resulting in an ionic bond. In hydrogen chloride, however, the electronegativity difference is not as great. Chloride has a greater affinity for the shared electrons than hydrogen, so the electrons in the shared bond between them are closer to chlorine, but the electrons are still shared, so the bonding between those two atoms is classified as polar covalent. Cl2 is nonpolar. HCl is polar. NaCl is ionic. In general, a covalent bond will at least be slightly polar if the atoms involved in the bond are not exactly alike. However, for all practical purposes, it is useful to consider the bond between C and H is nonpolar as well. So in general, bonds between C and H are nonpolar. Bonds between 2 like atoms are nonpolar, and most other covalent bonds between unlike atoms are at least slightly polar. For a molecule to contain an overall dipole moment and therefore be polar overall, that molecule has to at the very least contain a polar covalent bond. Even so, sometimes molecules that do contain polar covalent bonds do not have an overall dipole moment. To determine the overall polarity, or the quality of possessing a negative and a positive end of a molecule, the shape of that molecule needs to be determined and will be discussed later in this text.

Chapter 4 Bonding

85

H 1 2.

a B .9 0 a C .7 0

Électronégativité

2

O l C 0 3.5 3. N 3.0 S 5 r C 2. B 8 2.5 2. P 1 B 2. Se 4 I 2.0 2. Si 5 .8 As 2. l 1 0 A 2. Te 1 e 1.5 t G 8 2. A 2 . 2. a 1 Sb G 6 1.9 Po 0 1. Sn 8 2. Zn . i 1 B 9 1.6 In 1. u C 9 1.7 Pb 9 d 1. C 1. i N 9 1.7 Ti 8 1. Ag 9 1. o . 1 C g H 9 1.9 Pd .2 1. Fe 2 .8 Au .4 h n 1 R 2 2 M 5 2. Pt 2 1. 2. Ru 2 r C 6 Ir 2. 2 1. 2. e Tc B 5 V 1.9 Os 2 1. 1.6 o 2. M Li 0 Ti 5 g 1.8 Re 9 M .2 1. 1. b 1. 1 N 1.6 W 7 Sc 3 a N 9 Zr 1. 1. a 0. 1.4 C Ta 5 Y 1.0 1. K 1.2 f 8 H 3 0. Sr 1. 1.0 La 0 b R .8 1. 0

4

0

4.0

2A

F

1A

3B

4B

5B

6B

7B

8B

1B

3.0–4.0

2B

3A

2.0–2.9

4A

1.5–1.9

5A 6A