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siL11177_fm_i_1.indd 1 10/16/13 1:15 PM CHEMISTRY: THE MOLECULAR NATURE OF MATTER AND CHANGE, SEVENTH EDITION Published by McGraw-Hill Education, 2 Penn Plaza, New York, NY 10121. Copyright © 2015 by McGraw-Hill Education. All rights reserved. Printed in the United States of America. Previous editions © 2012, 2009, and 2006. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of McGraw-Hill Education, including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. Some ancillaries, including electronic and print components, may not be available to customers outside the United States. This book is printed on acid-free paper. 1 2 3 4 5 6 7 8 9 0 DOW/DOW 1 0 9 8 7 6 5 4 ISBN 978–0–07–351117–7 MHID 0–07–351117–X Senior Vice President, Products & Markets: Kurt L. Strand Vice President, General Manager, Products & Markets: Marty Lange Vice President, Content Production & Technology Services: Kimberly Meriwether David Managing Director: Thomas Timp Executive Brand Manager: David Spurgeon, Ph.D. Director of Development: Rose Koos Senior Development Editor: Lora Neyens Executive Marketing Manager: Tamara L. Hodge Director of Digital Content: Shirley Hino, Ph.D. Director, Content Production: Terri Schiesl Content Project Manager (print): Peggy Selle Content Project Manager (media): Laura Bies Senior Buyer: Sandy Ludovissy Senior Designer: David W. Hash Cover Image: @Victor Habbick Visions/Getty Images, Lachina Publishing Services Senior Content Licensing Specialist: Lori Hancock Compositor: Lachina Publishing Services Typeface: 10/12 Times Printer: R. R. Donnelley All credits appearing on page or at the end of the book are considered to be an extension of the copyright page. Library of Congress Cataloging-in-Publication Data Silberberg, Martin S. (Martin Stuart), 1945- Chemistry : the molecular nature of matter and change / Martin S. Silberberg, Patricia Amateis, Virginia Polytechnic. – Seventh edition. pages cm Includes index. ISBN 978–0–07–351117–7 — ISBN 0–07–351117–X (hard copy : alk. paper) 1. Chemistry–Textbooks. I. Amateis, Patricia. II. Title. QD33.2.S55 2015 540–dc23 2013033592 The Internet addresses listed in the text were accurate at the time of publication. The inclusion of a website does not indicate an endorsement by the authors or McGraw-Hill Education, and McGraw-Hill Education does not guarantee the accuracy of the information presented at these sites. www.mhhe.com siL11177_fm_i_1.indd 2 10/16/13 1:15 PM To Ruth and Daniel, with all my love and gratitude. MSS To Ralph, Eric, Samantha, and Lindsay: you bring me much joy. PGA siL11177_fm_i_1.indd 3 10/16/13 1:15 PM BRIEF CONTENTS Preface xx Acknowledgments xxxi 1 Keys to the Study of Chemistry 2 2 The Components of Matter 40 3 Stoichiometry of Formulas and Equations 90 4 Three Major Classes of Chemical Reactions 138 5 Gases and the Kinetic-Molecular Theory 198 6 Thermochemistry: Energy Flow and Chemical Change 250 7 Quantum Theory and Atomic Structure 286 8 Electron Configuration and Chemical Periodicity 322 9 Models of Chemical Bonding 358 10 The Shapes of Molecules 394 11 Theories of Covalent Bonding 428 12 Intermolecular Forces: Liquids, Solids, and Phase Changes 454 13 The Properties of Mixtures: Solutions and Colloids 516 14 Periodic Patterns in the Main-Group Elements 568 15 Organic Compounds and the Atomic Properties of Carbon 616 16 Kinetics: Rates and Mechanisms of Chemical Reactions 674 17 Equilibrium: The Extent of Chemical Reactions 730 18 Acid-Base Equilibria 776 19 Ionic Equilibria in Aqueous Systems 826 20 Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions 876 21 Electrochemistry: Chemical Change and Electrical Work 918 22 The Elements in Nature and Industry 976 23 Transition Elements and Their Coordination Compounds 1016 24 Nuclear Reactions and Their Applications 1052 Appendix A Common Mathematical Operations in Chemistry A-1 Appendix B Standard Thermodynamic Values for Selected Substances A-5 Appendix C Equilibrium Constants for Selected Substances A-8 Appendix D Standard Electrode (Half-Cell) Potentials A-14 Appendix E Answers to Selected Problems A-15 Glossary G-1 Credits C-1 Index I-1 iv siL11177_fm_i_1.indd 4 10/16/13 1:15 PM 15 organic Compounds and the atomic properties of Carbon 15.1 The Special Nature of Carbon and the Alkenes 15.5 The Monomer-Polymer Theme I: Characteristics of Organic Geometric (Cis-Trans) Isomerism Synthetic Macromolecules Molecules Alkynes Addition Polymers Structural Complexity of Organic Aromatic Hydrocarbons Condensation Polymers Molecules Catenated Inorganic Hydrides 15.6 The Monomer-Polymer Theme II: Chemical Diversity of Organic 15.3 Some Important Classes of Biological Macromolecules Molecules Organic Reactions Sugars and Polysaccharides 15.2 The Structures and Classes Types of Organic Reactions Amino Acids and Proteins of Hydrocarbons Organic Redox Reactions Nucleotides and Nucleic Acids Carbon Skeletons and Hydrogen Skins 15.4 Properties and Reactivities of Alkanes Common Functional Groups Dispersion Forces and the Physical Groups with Only Single Bonds Properties of Alkanes Groups with Double Bonds Constitutional Isomerism Groups with Both Single and Double Chiral Molecules and Optical Bonds Isomerism Groups with Triple Bonds siL11177_ch15_0616_0673.indd 616 8/30/13 8:19 AM Concepts and Skills to Review Before You Study This Chapter c naming straight-chain alkanes (Section 2.8) c (cid:30) and (cid:29) bonding (Section 11.2) c constitutional isomerism (Section 3.2) c intermolecular forces and synthetic and biological macromolecules (Sections 12.3, 12.7, and 13.2) c (cid:31)EN and bond polarity (Section 9.5) c properties of the Period 2 elements (Section 14.2) c resonance structures (Section 10.1) c properties of the Group 4A(14) elements c VSEPR theory (Section 10.2) (Section 14.6) c orbital hybridization (Section 11.1) A side from the air and the water in the sugar solution, everything in the photo (opposite)—hummingbird, plants, sugar, and plastic feeder—consists of organic compounds. And so does nearly everything you put into or on your body—food, medicine, cosmetics, and clothing. Organic fuels warm our homes, cook our meals, and power our vehicles. Major industries are devoted to producing organic compounds, including plastics, pharmaceuticals, and insecticides. What is an organic compound? According to the dictionary, it is “a compound of carbon,” but that definition is too general because carbonates, cyanides, carbides, cyanates, and so forth, also contain carbon but are classified as inorganic. Here is a more specific definition: all organic compounds contain carbon, nearly always bonded to other carbons and hydrogen, and often to other elements. In the early 19th century, organic compounds were usually obtained from liv- ing things, so they were thought to possess a spiritual “vital force,” which made them impossible to synthesize and fundamentally different from inorganic compounds. But, in 1828, Friedrich Wöhler destroyed this notion when he obtained urea by heat- ing ammonium cyanate. Today, we know that the same chemical principles govern organic and inorganic systems because the behavior of a compound—no matter how amazing—can be explained by understanding the properties of its elements. IN THIS CHAPTER . . . We see that the structures and reactivities of organic molecules emerge naturally from the properties of their component atoms. c We begin by reviewing the atomic properties of carbon and seeing how they lead to the complex structures and reactivity of organic molecules. c We focus on drawing and naming hydrocarbons as a prelude to naming other types of organic compounds. c We classify the main types of organic reactions in terms of bond order and apply them to the functional groups that characterize families of organic compounds. c We examine the giant organic molecules of commerce and life—synthetic and natural polymers. 15.1 THE SPECIAL NATURE OF CARBON AND THE CHARACTERISTICS OF ORGANIC MOLECULES Although there is nothing mystical about organic molecules, their indispensable role in biology and industry leads us to wonder if carbon is somehow special. Of course, each element has specific properties, but the atomic properties of carbon do give it bonding capabilities beyond those of any element, and this exceptional behavior leads to the two characteristics of organic molecules—structural complexity and chemical diversity. siL11177_ch15_0616_0673.indd 617 8/30/13 8:46 AM 618 Chapter 15 • Organic Compounds and the Atomic Properties of Carbon The Structural Complexity of Organic Molecules Most organic molecules have more complex structures than most inorganic molecules. A quick review of carbon’s atomic properties and bonding behavior shows why. 1. Electron configuration, electronegativity, and bonding. Carbon forms covalent, He rather than ionic, bonds in all its elemental forms and compounds. This bonding 1 H 2 Li Be B C N O F Ne behavior is the result of carbon’s electron configuration and electronegativity: 3 Si P S Cl • Carbon’s ground-state electron configuration of [He] 2s22p2—four electrons more Period 45 GSen BIr tgheatnic aHlley a inmd pfoosusri bfelew eurn tdhearn o Nrdei—namrye acnosn dthitaito tnhse. fTohrem laotisosn o off fcoaurrb oen2 itoon sf oirsm e ntehre- 6 Pb C41 cation requires the sum of IE through IE ; the gain of four e2 to form the 7 1(1A) 2(2A) 3(1A3)14(11A44)G5(1A5ro)6(1uA6p)7(1A7)8(1A8) • eLCny4d2ino gathn aeitor mnth irece .cqeunirteers othf eP seurimod o 2f ,E cAar11b tohnr ohuagsh a En Ae4l4e, ctthreo nlaegsta ttihvrietye s(EteNps 5 o f2 w.5h) icthha ta ries Figure 15.1 T he position of carbon in the midway between that of the most metallic element (Li, EN 5 1.0) and the most non- periodic table. metallic active element (F, EN 5 4.0) (Figure 15.1). 2. Catenation, bond properties, and molecular shape. The number and strength of carbon’s bonds lead to its property of catenation, the ability to bond to itself repeat- edly, which results in a multitude of chemically and thermally stable chain, ring, and branched compounds: • Through the process of orbital hybridization (Section 11.1), carbon forms four bonds in virtually all its compounds, and they point in as many as four different directions. • The small size of carbon allows close approach to another atom and thus greater orbital overlap, so carbon forms relatively short, strong bonds. • The C¬C bond is short enough to allow side-to-side overlap of half-filled, unhybridized p orbitals and the formation of multiple bonds. These restrict rotation of attached groups (see Figure 11.13, p. 439), leading to additional structures. 3. Molecular stability. Although silicon and several other elements catenate also, none forms chains as stable as those of carbon. Atomic and bonding properties explain why C chains are so stable and, therefore, so common: • Atomic size and bond strength. As atomic size increases down Group 4A(14), bonds between identical atoms become longer and weaker. Thus, a C¬C bond (347 kJ/mol) is much stronger than an Si¬Si bond (226 kJ/mol). • Relative enthalpies of reaction. A C¬C bond (347 kJ/mol), a C¬O bond (358 kJ/mol), and a C¬Cl bond (339 kJ/mol) have nearly the same energy, so relatively little heat is released when a C chain reacts and one bond replaces the other. In contrast, an Si¬O bond (368 kJ/mol) or an Si¬Cl bond (381 kJ/mol) is much stronger than an Si¬Si bond (226 kJ/mol), so the large quantity of heat released when an Si chain reacts favors reactivity. • Orbitals available for reaction. Unlike C, Si has low-energy d orbitals that can be attacked (occupied) by the lone pairs of incoming reactants. Thus, for example, ethane (CH ¬CH ) is stable in water and reacts in air only when sparked, 3 3 whereas disilane (SiH ¬SiH ) breaks down in water and ignites spontaneously 3 3 in air. The Chemical Diversity of Organic Molecules In addition to their complex structures, organic compounds are remarkable for their sheer number and diverse chemical behavior. Several million organic compounds are known, and thousands more are discovered or synthesized each year. This diversity is also founded on atomic behavior and is due to three interrelated factors—bonding to heteroatoms, variations in reactivity, and the occurrence of functional groups. siL11177_ch15_0616_0673.indd 618 8/30/13 8:19 AM 15.1 • The Special Nature of Carbon and the Characteristics of Organic Molecules 619 1. Bonding to heteroatoms. Many organic compounds contain heteroatoms, CH CH CH CH OH atoms other than C or H. The most common heteroatoms are N and O, but S, P, and 3 2 2 2 the halogens often occur, and organic compounds with other elements are known CH CH 3 3 as well. Figure 15.2 shows that 23 different molecular structures are possible from CH CH CH OH CH C CH 3 2 3 3 various arrangements of four C atoms singly bonded to each other, just one O atom OH (either singly or doubly bonded), and the necessary number of H atoms. O CH CH CH CH CH C 3 2 3 2 2. Electron density and reactivity. Most reactions start—that is, a new bond OH CH CH begins to form—when a region of high electron density on one molecule meets a 2 2 region of low electron density on another. These regions may be due to the proper- CH CH CH O CH 3 2 2 3 ties of a multiple bond or a carbon-heteroatom bond. Consider the reactivities of four O bonds commonly found in organic molecules: CH CH CH CH CH O • The C±C bond. When C is singly bonded to another C, as occurs in portions of 3 3 2 nearly every organic molecule, the EN values are equal and the bond is nonpolar. CH3 CH CH2 Therefore, in most cases, C±C bonds are unreactive. CH CH CH C O • The C±H bond. This bond, which also occurs in nearly every organic molecule, is 3 2 2 short (109 pm) and, with EN values of H (2.1) and C (2.5), very nearly nonpolar. H OH Thus, C±H bonds are largely unreactive. CH CH C CH CH CH • The C±O bond. This bond, which occurs in many types of organic molecules, 3 2 3 2 O CH CH is highly polar (DEN 5 1.0), with the O end electron rich and the C end electron 2 2 poor. As a result of this imbalance in electron density, the C±O bond is reactive O O (easy to break), and, given appropriate conditions, a reaction will occur there. CH2 CH CH2 CH3 CH2 CH2 • Bonds to other heteroatoms. Even when a carbon-heteroatom bond has a CH CH 2 2 small DEN, such as that for C±Br (DEN 5 0.3), or none at all, as for C±S (DEN 5 0), the heteroatoms are generally large, so their bonds to carbon are long, CH3 CH2 O CH2 CH3 weak, and thus reactive. CH CH O 3 2 3. Importance of functional groups. The central feature of most organic mol- CH CH C O CH CH CH ecules is the functional group, a specific combination of bonded atoms that reacts 3 2 3 in a characteristic way, no matter what molecule it occurs in. In nearly every case, CH H 2 the reaction of an organic compound takes place at the functional group. (In fact, CH2 CH CH2 OH O as you’ll see in Section 15.3, we often write a general symbol for the remainder of CH C the molecule because it stays the same while the functional group reacts.) Functional 2 CH CH O CH CH CH CH groups vary from carbon-carbon multiple bonds to several combinations of carbon- 2 3 2 3 CH heteroatom bonds, and each has its own pattern of reactivity. A particular bond may 3 be a functional group itself or part of one or more functional groups. For example, CH CH2 the C±O bond occurs in four functional groups. We will discuss the reactivity of CH2 CH OH CH2 CH C O three of these groups in this chapter: H CH3 O O CH CH O CH CH C CH W O X W 3 3 2 3 ±C±O±H X ±C±O±C± W ±C±O±H W CH3 alcohol group carboxylic acid group ester group Figure 15.2 H eteroatoms and different bonding arrangements lead to great g Summary of Section 15.1 chemical diversity. c Carbon’s small size, intermediate electronegativity, four valence electrons, and ability to form multiple bonds result in the structural complexity of organic compounds. c These factors lead to carbon’s ability to catenate, which creates chains, branches, and rings of C atoms. Small size and absence of d orbitals in the valence level lead to strong, chemically resistant bonds that point in as many as four directions from each C. c Carbon’s ability to bond to many other elements, especially O and N, creates polar, reactive bonds, which leads to the chemical diversity of organic compounds. c Most organic compounds contain functional groups, specific combinations of bonded atoms that react in characteristic ways. siL11177_ch15_0616_0673.indd 619 9/19/13 12:58 PM 620 Chapter 15 • Organic Compounds and the Atomic Properties of Carbon 111555...222 THE STRUCTURES AND CLASSES OF HYDROCARBONS Let’s make an anatomical analogy between an organic molecule and an animal. The carbon-carbon bonds form the skeleton: the longest continual chain is the backbone, and any branches are the limbs. Covering the skeleton is a skin of hydrogen atoms, with functional groups protruding at specific locations, like chemical hands ready to grab an incoming reactant. In this section, we “dissect” one group of compounds down to their skeletons and see how to draw and name them. Hydrocarbons, the simplest type of organic compound, contain only H and C atoms. Some common fuels, such as natural gas and gasoline, are hydrocarbon mixtures. Some hydrocarbons, such as ethylene, acetylene, and benzene, are important feedstocks, precursor reactants used to make other compounds. Carbon Skeletons and Hydrogen Skins We’ll begin by examining the possible bonding arrangements of C atoms only (leav- ing off the H atoms for now) in simple skeletons without multiple bonds or rings. To distinguish different skeletons, focus on the arrangement of C atoms (that is, the successive linkages of one to another) and keep in mind that groups joined by a single (sigma) bond are relatively free to rotate (Section 11.2). Number of C Atoms and Number of Arrangements One, two, or three C atoms can be arranged in only one way. Whether you draw three C atoms in a line or with a bend, the arrangement is the same. Four C atoms, however, have two possible arrangements±a four-C chain or a three-C chain with a one-C branch at the central C: C C C C C same as C C C C C C same as C C C C C When we show the chains with bends due to the tetrahedral C (as in the ball-and-stick models above), the different arrangements are especially clear. Notice that if the branch is added to either end of the three-C chain, it is simply a bend in a four-C chain, not a different arrangement. Similarly, if the branch points down instead of up, it represents the same arrangement because single-bonded groups rotate. As the total number of C atoms increases, the number of different arrangements increases as well. Five C atoms joined by single bonds have 3 possible arrangements (Figure 15.3A); 6 C atoms can be arranged in 5 ways, 7 C atoms in 9 ways, 10 C atoms in 75 ways, and 20 C atoms in more than 300,000 ways! If we include multiple bonds and rings, the number of arrangements increases further. For example, Figure 15.3 S ome five-carbon skeletons. A C C C C C B C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C siL11177_ch15_0616_0673.indd 620 8/30/13 8:19 AM