Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015)

Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015) Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015) Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015) Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015) Preview Introductory chemistry atoms first, Fifth edition by Steve Russo, Mike Silver (2015)

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Library of Congress Cataloging-in-Publication Data

Russo, Steve, 1951 July 18—

Introductory chemistry : atoms first / Steve Russo, Ithaca College, Mike Silver, Hope College — Fifth edition.

pages cm

Includes index.

ISBN-13: 978-0-321-92711-8 (alk paper)

ISBN-10: 0-321-92711-7 (alk paper)

1 Chemistry—Textbooks I Silver, Mike, 1953– II Title.

QD33.2.R87 2015

540—dc23

2013028072

1 2 3 4 5 6 7 8 9 10—CRK—17 16 15 14 13

Assistant Editor: Lisa R Pierce

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ISBN-10:  0-321-92711-7 ISBN-13: 978-0-321-92711-8

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About the Authors

Steve Russo (right) has taken an early retirement

as a Senior Lecturer in the Department of

Chemistry at Cornell University and is now

teach-ing chemistry part time at Ithaca College Prior

to that, he was an Assistant Professor at Indiana

University While there, he designed and

imple-mented a state-of-the-art computer resource

cen-ter for the undergraduate chemistry curriculum

He received his B.S in chemistry from St Francis

College in New York City and his Ph.D in

physi-cal organic chemistry from Cornell University He

is a member of the American Chemical Society

and has been a recipient of the Dupont Teaching

Award, Clark Teaching Awards while at Cornell

University, and an Amoco Distinguished

Teach-ing Award from Indiana University

Mike Silver (left) is a Professor Emeritus of Chemistry at Hope College He

received his B.S in chemistry from Farleigh Dickinson University in New Jersey

and his Ph.D in inorganic chemistry from Cornell University He is also a

member of the American Chemical Society (ACS) and past president of the

ACS West Michigan Section, as well as a member of the Society of Cosmetic

Chemists He has received the Camille and Henry Dreyfus Teacher-Scholar

Award for Excellence in Teaching and Research and the Provost’s Award

for Teaching Excellence Currently, he teaches a course a semester at Hope

College or Grand Rapids Community College, and he also serves as a

consul-tant to the chemical and manufacturing industries in projects ranging from

cancer drug design and synthesis to electrochromic automobile mirrors to

adhesives for use in oral applications Dr Silver has designed and

synthe-sized a variety of novel molecules, including an immune system stimulator to

combat skin cancer and eczema, and an emulsifier that allows oil and water to

coexist in what is called a multiple or triple emulsion Both have been

submit-ted for patent protection

Brief Contents

C h a p t e r 1 What Is Chemistry? 3

C h a p t e r 2 The Numerical Side of Chemistry 29

C h a p t e r 3 The Evolution of Atomic Theory 79

C h a p t e r 4 The Modern Model of the Atom 121

C h a p t e r 5 Chemical Bonding and Nomenclature 167

C h a p t e r 6 The Shape of Molecules 217

C h a p t e r 7 Intermolecular Forces and the Phases of Matter 253

C h a p t e r 8 Chemical Reactions 283

C h a p t e r 9 Stoichiometry and the Mole 315

C h a p t e r 1 0 Electron Transfer in Chemical Reactions 363

C h a p t e r 1 1 What If There Were No Intermolecular Forces? The Ideal Gas 413

C h a p t e r 1 7 The Chemistry of Carbon 691

C h a p t e r 1 8 Synthetic and Biological Polymers 737

About the Authors iii Preface x

One More thing 20

C h a p t e r 2 The Numerical Side of Chemistry 29

2.1 Numbers in Chemistry—precision and accuracy 29 2.2 Numbers in Chemistry—Uncertainty and Significant Figures 32 2.3 Zeros and Significant Figures 34

2.4 Scientific Notation 37 2.5 how to handle Significant Figures and Scientific Notation When Doing Math 41

2.6 Numbers With a Name—Units of Measure 45 2.7 Density: a Useful physical property of Matter 50 2.8 Doing Calculations in Chemistry—Unit analysis 52 2.9 rearranging equations—algebraic Manipulations With Density 58

2.10 One More thing Quantifying energy 60

C h a p t e r 3 The Evolution of Atomic Theory 79

3.1 Dalton’s atomic theory 79 3.2 Development of a Model for atomic Structure 83 3.3 the Nucleus 84

3.4 the Structure of the atom 88 3.5 the Law of Mendeleev—Chemical periodicity 93 3.6 the Modern periodic table 97

3.7 an Introduction to Ions and the First Ionization energy 103 3.8 One More thing Isotopes, Mass Spectrometers, and extraterrestrial Origins 108

C h a p t e r 4 The Modern Model of the Atom 121

4.1 Seeing the Light—a New Model of the atom 121 4.2 a New Kind of physics—energy Is Quantized 124 4.3 the Bohr theory of atomic Structure 125 4.4 periodicity and Line Spectra explained 128 4.5 Subshells and electron Configuration 135 4.6 regular Variations in the properties of elements 142

4.7 Compound Formation and the Octet rule 146 4.8 One More thing the Modern Quantum Mechanical Model of the atom 150

C h a p t e r 5 Chemical Bonding and Nomenclature 167

5.1 Ionic Bonding 167 5.2 Molecules—What are they? Why are they? 170 5.3 holding Molecules together—the Covalent Bond 171 5.4 Molecules, Dot Structures, and the Octet rule 177 5.5 Multiple Bonds 182

5.6 equal versus Unequal Sharing of electrons—electronegativity and the polar Covalent Bond 187

5.7 Nomenclature—Naming Chemical Compounds 192 5.8 One More thing exceptions to the Octet rule 201

C h a p t e r 6 The Shape of Molecules 217

6.1 the Importance of Molecular Shape 217 6.2 Valence Shell electron pair repulsion (VSepr) theory 219 6.3 polarity of Molecules, or When Does 2 + 2 Not equal 4? 228 6.4 Intermolecular Forces—Dipolar Interactions 236

6.5 One More thing VSepr theory for Molecules possessing expanded Octet atoms 238

C h a p t e r 7 Intermolecular Forces and the Phases

of Matter 2537.1 Why Does Matter exist in Different phases? 253 7.2 Intermolecular Forces 259

7.3 a Closer Look at Dipole Forces—hydrogen-Bonding 262 7.4 Nonmolecular Substances 266

7.5 One More thing Vancomycin—the antibiotic of Last resort and Its Five Life-Saving hydrogen Bonds! 270

C h a p t e r 8 Chemical Reactions 283

8.1 What Is a Chemical reaction? 283 8.2 how are reactants transformed into products? 284 8.3 Balancing Chemical equations 287

8.4 types of reactions 290 8.5 Solubility and precipitation reactions 293 8.6 Introduction to acid–Base reactions 299 8.7 One More thing Chemical Synthesis 301

C h a p t e r 9 Stoichiometry and the Mole 315

9.1 Stoichiometry—What Is It? 316 9.2 the Mole 319

9.3 reaction Stoichiometry 326 9.4 Dealing With a Limiting reactant 333 9.5 Combustion analysis 338

9.6 Going from Molecular Formula to percent Composition 344 9.7 One More thing Nonstoichiometric Compounds 346

C h a p t e r 1 0 Electron Transfer in Chemical Reactions 363

10.1 What Is electricity? 363 10.2 electron Bookkeeping—Oxidation States 364 10.3 recognizing electron-transfer reactions 376 10.4 electricity from redox reactions 380 10.5 Which Way Do electrons Flow?—the eMF Series 388 10.6 another Look at Oxidation: the Corrosion of Metals 393 10.7 One More thing Less Common Oxidation States and Chemical reactivity 397

C h a p t e r 1 1 What If There Were No Intermolecular Forces?

The Ideal Gas 413

11.1 Describing the Gas phase—P, V, n, and T 413

11.2 Describing a Gas Mathematically—the Ideal Gas Law 419 11.3 Getting the Most from the Ideal Gas Law 425

11.4 One More thing Deviations from Ideality 435

C h a p t e r 1 2 Solutions 449

12.1 What Is a Solution? 449 12.2 energy and the Formation of Solutions 452 12.3 entropy and the Formation of Solutions 459 12.4 Solubility, temperature, and pressure 462 12.5 Molarity 464

12.6 percent Composition 473 12.7 reactions in Solution 476 12.8 Colligative properties of Solutions 483 12.9 One More thing Getting Unlikes to Dissolve—Soaps and Detergents 494

C h a p t e r 1 3 When Reactants Turn into Products 513

13.1 Chemical Kinetics 514 13.2 energy Changes and Chemical reactions 516 13.3 reaction rates and activation energy—Getting over the hill 523

13.4 how Concentration affects reaction rate 531 13.5 reaction Order 536

13.6 One More thing Why reaction Orders have the Values they Do—Mechanisms 540

C h a p t e r 1 4 Chemical Equilibrium 559

14.1 Dynamic equilibrium—My reaction Seems to have Stopped! 559

14.2 Why Do Chemical reactions reach equilibrium? 565

14.3 the position of equilibrium—the equilibrium Constant, Keq 568

14.4 Disturbing a reaction already at equilibrium—Le Chatelier’s principle 575

14.5 how equilibrium responds to temperature Changes 578 14.6 equilibria for heterogeneous reactions 581

14.7 One More thing Solubility and equilibrium Calculations 584

C h a p t e r 1 5 Electrolytes, Acids, and Bases 603

15.1 electrolytes and Nonelectrolytes 603 15.2 electrolytes Weak and Strong 609 15.3 acids Weak and Strong 611 15.4 Bases—the anti-acids 615 15.5 help! I Need another Definition of acid and Base 618 15.6 Weak Bases 621

15.7 Is this Solution acidic or Basic? Understanding Water, autodissociation, and Kw 623

15.8 the ph Scale 628 15.9 One More thing resisting ph Changes—Buffers 633

C h a p t e r 1 6 Nuclear Chemistry 655

16.1 the Case of the Missing Mass—Mass Defect and the Stability

of the Nucleus 655 16.2 half-Life and the Band of Stability 660 16.3 Spontaneous Nuclear Changes— radioactivity 662 16.4 Using radioactive Isotopes to Date Objects 672 16.5 Nuclear energy—Fission and Fusion 675 16.6 One More thing Biological effects and Medical applications

of radioactivity 679

C h a p t e r 1 7 The Chemistry of Carbon 691

17.1 Carbon—a Unique element 692 17.2 Naturally Occurring Compounds of Carbon and hydrogen—hydrocarbons 696

17.3 Naming hydrocarbons 702 17.4 properties of hydrocarbons 713 17.5 Functionalized hydrocarbons—Bring On the heteroatoms 714

17.6 One More thing Functional Groups and Organic Synthesis 726

C h a p t e r 1 8 Synthetic and Biological Polymers 737

18.1 Building polymers 737 18.2 polyethylene and Its relatives 738 18.3 Nylon—a polymer You Can Wear 742 18.4 polysaccharides and Carbohydrates 744 18.5 proteins 747

18.6 One More thing DNa—the Master Biopolymer 751 Glossary G-1

Selected Answers A-1Credits C-1

Index I-1

Many instructors have told us that our text is the most readable

introduc-tory chemistry textbook their students have ever used They also told

us that their students can use as much help as possible when learning how to solve problems With each edition we have included more worked examples and more end-of-chapter problems, including one-step-beyond problems, visu-ally oriented and concept-based problems, and in-class group exercises, and stronger tools to help students learn the skills they need To make the mate-rial more memorable, we have chapter-opening “teasers.” These are stories and anecdotes utilizing materials from history to the present day that pertain to the material in the chapter and are fun and interesting to read Also, every edition of

our text, starting from the first, has employed an “atoms first approach.” Why

atoms first? The simple answer is that this is the way we have always taught this material since we began teaching decades ago Both of us were influenced

by the late Professor Michell J Sienko of Cornell University, a textbook author himself and a fabulously talented lecturer who could hold the attention of 500 students at a time His textbook and lectures always built up the material from the “bottom up,” from atoms to molecules to properties of molecules to stoichi-ometry and reactions and beyond It instantly made sense for us to teach this way Following an atoms first approach, we never had to say things like “I’m teaching you this now because it’s covered in lab this week,” or “This will make more sense when we cover polarity later.” When building a house, one doesn’t usually pour half of the foundation, start work on the second floor, and return later to complete the foundation In the same way, the atoms first approach lays

a proper foundation and then continually builds atop it; while it gives some choice as to the order of topics, the path it builds is consistently straightforward and does not have leaps of faith or distracting U-turns

Our goal with this text has always been to help students make sense of chemistry As chemists, we know that chemistry is intrinsically interesting, that its principles do form a reasonably coherent whole, and that its problem- solving skills can be mastered by anyone But, too often, students see the subject

as incomprehensible and the course as a frightening labyrinth All too frequently, they fall back on rote learning—memorizing algorithms, plugging numbers into formulas, and forgetting much of what they learned starting as soon as the pen-cil is dropped at the end of the final exam As chemistry instructors, we hate to see that Therefore, we designed this book to promote comprehension and prob-lem solving as complementary skills A student who understands the principles

of chemistry does not have to rely strictly on memorization and is more likely to enjoy and retain the material This understanding and sufficient practice at solv-ing problems will help students master the principles We hope that our book will help students come out of the course with a body of knowledge and skills that will serve them and that they will want to retain

New to This Edition

What can authors possibly add to a fifth edition of a textbook? The answer turns out to be “Plenty!”

1 Learning Outcomes: Each end-of-chapter review section now begins with a

table of learning outcomes for each section of the chapter, correlated to the

end-of-chapter problems The learning outcomes consist of goals and skills

the student should learn and practice before moving on to the next chapter

2 One More Thing: We have always been proud of the conceptual depth

that this book plumbs, but some instructors have told us that they skip

sections that go to great conceptual depth Still, we wanted to add even

more of this depth for this fifth edition that other reviewers and users have

asked for How to satisfy both? Our solution was to create a final section

for every chapter titled “One More Thing.” Being so titled, it gives the

instructor an option to skip it and be guilt-free when time requirements

are tight We have made sure that it can be skipped without doing damage

to the flow of the material that follows In some cases, this section contains

material that was previously incorporated in the main body of the chapter

in the previous edition In other cases it contains totally new material that

we thought would be great to add for its conceptual and interest value

Now the instructor, and each individual student, has the option to jump

into the deepest end of the conceptual pool if he or she wants

3 WorkPatches Hints Available in MasteringChemistry: Judging from

instructor and student feedback over the years, WorkPatches have always

been a favorite feature of this book They were always meant to be a way

to break the reader out of the passive reading mode and make students

more interactive by encouraging them to think about what was just read

before going on They accomplish this by posing a conceptual question,

followed by a continuation of the main text that assumes the question was

successfully answered without ever revealing the actual answer Skipping

a WorkPatch therefore is like joining in the middle of a conversation,

something a reader would not want to do We realize we are forcing the

reader to do something here, and the answers are provided at the end of

the chapter, but we don’t want readers looking up these answers without

first trying to come up with an answer on their own So, in this edition,

for the first time, we offer some help and something in step with the

times Today many, if not most, students have a smartphone Included

in the fifth edition is a QR code that will link the reader’s phone to a site

where he or she can get a hint to any WorkPatch Given the love affair

that students have with this technology, our hope is that this will be an

incentive for them to interact more with the text For readers who do not

have a smartphone or a tablet, the hints can still be accessed by visiting

MasteringChemistry for the fifth edition

4 Concept Questions: In this edition we wanted to give readers more than

just lists of topics that we call “Have You Learned This?” and summaries

that we call “Skills to Know,” which we have always included at the

end of each chapter Now, for the first time, each chapter ends with ten

multiple-choice questions called “Concept Questions.” These are meant to

be done quickly and will give readers an opportunity to see if they have

grasped the fundamental concepts presented in the chapter Instructors

know that if we throw a little technobabble at students, we can often shake

students’ confidence in what they know The concept questions often use

this approach, but if students have a true understanding, then smoke won’t

get in the way of their finding the correct response The concept questions

give them this opportunity

5 New End-of-Chapter Problems: As always, we endeavor to refine and

improve our end-of-chapter problems We have gone through each chapter and, based on our own ideas and with input from users, replaced or improved more than 20% of the existing end-of-chapter questions We receive many compliments on the number, variety, and quality of our end-of-chapter problems Every instructor knows the value of time students spend working on such problems As Professor Sienko would tell every one

of his classes on the first day, “If you are not in some degree of pain during this course, you are not learning.” Our book provides an enjoyable read due to its conversational style, atoms first approach, conceptual depth, and clean layout The pain comes from struggling with well-thought-out end-of-chapter problems Of course, the payback is good performance on exams and a lifelong retention of the major concepts of chemistry

The conversational tone and the atoms first approach have always been and remain the principle hallmarks of our text We are big believers in their power to help students learn With each new edition, and with generous help from our users, we have hunted down errors and hopefully corrected them all

If you find any, please email us at silver@hope.edu (Mike Silver) and srusso@ithaca.edu (Steve Russo) Please send along any other comments you might have as well, good or bad We love hearing from our users, and we accept constructive criticism reasonably well (although we prefer high praise)

Promoting Active Learning

How can we, as textbook authors, promote active learning? First, quite ply, we provide a book that makes sense to students A student who under-stands the material is less likely to fall back on passive memorization As one instructor told us, “This book allows me to spend class time doing hands-on learning versus spending time explaining the book.”

sim-Second, we incorporate devices to encourage active reading A flip through the book will show many sets of practice problems These practice problems are located so that students can immediately apply the skill the text has just presented They are presented in sets of three or four; the first problem is solved step-by-step in the text, and the answers to the others are given at the back of the book Each chapter contains an average of 25 practice problems.However, we are not nạve We know that many students routinely skip over these in-chapter practice problems Therefore, we have included concep-tual practice problems called WorkPatches A WorkPatch is a “stealth” prob-lem It follows smoothly from the preceding text and is not boxed off What is more, a student who tries to read through a WorkPatch without solving it will find that the subsequent text refers to, and often depends on, the answer—but does not say what it is (The solutions to all WorkPatches are given at the end of the chapter.) In some cases, a WorkPatch serves as the springboard into the next topic, and all WorkPatches are now connected to hints, which can be accessed

by scanning the QR code in the next few pages or back of the textbook Patches are denoted by a yellow stop sign/red light icon

Work-Helping Students Master Problem-Solving Skills

An instructor flipping through our text might be inclined to ask, “Where are all the worked examples?” In fact, this text has an abundance of worked examples and other problem-solving aids, but we have handled them in a way

that preserves the text’s coherence As in the previous editions, many worked

examples are presented in the text itself We feel strongly that problem-

solving techniques should be explained with the same care and continuity we

use for concepts

When students are working on problems, however, they also need access

to compact summaries and examples We have augmented these resources in

the following ways:

■ Important problem-solving methods are summarized in charts in the text

■ The same charts, accompanied by worked examples and additional material,

appear in a special Skills to Know section at the end of the chapter

imme-diately preceding the end-of-chapter problems This section is intended

as a “help center” to which students can refer while working problems

(A few of the more purely conceptual chapters do not have a Skills to Know

section.)

■ An abundance of additional step-by-step methods, worked examples, and

practice problems are provided in the Student Workbook and Selected

Solu-tions that accompanies the text, authored by our colleagues Saundra Yancy

McGuire and Elzbieta Cook at Louisiana State University For a weak or

struggling student, nothing is more important than abundant, guided,

confidence-building practice This workbook enables us to offer a truly

realistic amount of help while maintaining a clean, readable textbook The

Workbook also contains a generous mathematics review We came to know

Dr McGuire when she directed the Center for Learning and Teaching at

Cornell; she currently directs the Center for Academic Success at Louisiana

State University We are extremely glad that she chose to join her expertise

with ours and are thankful to Elzbieta Cook for agreeing to revise the

sup-plements for the fifth edition

■ As noted earlier, each chapter contains internal practice problems and

WorkPatches in addition to end-of-chapter problems

Room to Practice: Extensive Problem Sets

■ Each problem set at the end of the chapter includes a section of additional

problems that are not categorized by chapter section

■ There are now even more visually oriented problems

■ Each problem set contains a sufficient abundance of each of the types of

problems an instructor might require

■ As in the previous editions, answers to selected problems are provided at

the end of the book (The full solutions for these selected problems, as well

as for all the practice problems, are available in the Student Workbook and

Selected Solutions manual.)

Making Chemistry Memorable

Instructors have told us that a surprising number of their students actually

read our book rather than using it mainly as a resource while solving

prob-lems We explain chemistry using everyday, conversational language, and we

tie the concepts and calculations to stories and examples that help bring them

to life We use humor in places We also ensure that the students know which

points are fundamental and which represent additional detail You will notice that most of the illustrations lack legends That is because the text and the illustrations work hand-in-hand, and each illustration is placed exactly where

it belongs

We Want to Hear from You

One of the pleasures of revising a book is hearing from instructors who use it—learning what works and doesn’t work, and gathering ideas If you have any comments or suggestions, please feel free to contact us at the following email addresses: srusso@ithaca.edu (Steve Russo); silver@hope.edu (Mike Silver)

We very much wish to acknowledge the people who were instrumental

in helping us with this fifth edition We are indebted to our editors,

Terry Haugen and Chris Hess, for believing enthusiastically in this book and

championing a fifth edition We very much want to thank Lisa Pierce, Jenna

Gray, Wendy Perez, and Gina Cheselka, our project managers These are the

people who are the conductors of the orchestra They overlook all the details,

crack the whip when necessary, and make sure the final product is

beauti-ful music rather than a cacophony of noise Fran Falk, our editorial

coordi-nator, was responsible for acquiring the prescriptive reviews, which greatly

helped shape the direction of this edition Divya Narayanan and Kerri Wilson

did a wonderful job in photo research and finding new images that were

needed We are very grateful to Wynne Au Yeung and Mark Ong, who were

in charge of the art and design program and are responsible for maintaining

and improving what we believe to be one of the key features of our book, its

clean, nonchoppy, and organized look that helps to make it so readable Our

genuine thanks also go to Wanda España who was in charge of the cover and

interior design We have had a tradition of some great and beautiful covers

for the book, and that tradition has been maintained We certainly also must

acknowledge Jonathan Cottrell, our marketing manager, whose job is to get

the message out about what makes this book so unique, and Jackie Jakob, our

associate content producer, who has led the effort to tie our book to

Master-ingChemistry, the extremely useful online tutorial and assessment program

We wish to extend our genuine thanks to the reviewers whose patient and

thoughtful comments helped us shape this fifth edition Their ability to

pro-vide excellent suggestions and find errors that we could not see no matter

how hard we looked was incredible

Jeff Allison, Austin Community

College

Chris Bahn, Montana State University

Michael Hauser, St Louis Community

Susan Thomas, University of Texas at San Antonio

Acknowledgments

We also want to thank Elzbieta Cook at Louisiana State University for her

efforts in updating the Student Workbook and Selected Solutions Manual as well

as the Instructors Guide and Complete Solutions Manual

With regard to the previous editions that helped to shape the nature of

this book, we want to thank all the people who have been involved over the

years In addition, for as long as new editions of this book are written, we will

always want to thank the people who were on board and who believed in the

vision and helped to create the earliest editions: Emiko Koike, Blakely Kim,

Irene Nunes, Jonathan Peck, Lisa Leung, Tony Asaro, and Saundra McGuire And last, but certainly not least, Maureen Kennedy, Joan Marsh, Margot Otway, and Ben Roberts—the original four chambers who helped to inspire and create the heart of this book We will always be in your debt.

Features examples from each chapter, learning objectives, review of key concepts from the text, and additional problems for student practice Also provides comprehensive answers and explanations to selected end-of-chapter problems from the text Provides over

200 worked examples and more than 550 practice problems and quiz questions to help students develop and practice their problem-solving skills.

with contributions from Chris Bahn of Montana State University.

Helps students develop data acquisition, organization, and analysis skills while teaching basic techniques Written to accompany the text, this manual offers 25 experiments This lab manual

is available via Catalyst: The Pearson Custom Laboratory Program for Chemistry This program allows you to custom build a chemistry lab manual that matches your content needs and course organization You can either write your own labs using the Lab Authoring Kit tool or select from the hundreds of labs available at http://www pearsonlearningsolutions.com/custom-library /catalyst This program also allows you to add your own course notes, syllabi, or other materials.

MasteringChemistry is the leading online homework and tutorial system for the sciences Instructors can create online assignments for their students by choosing from a wide range of items, including end- of-chapter problems and research-enhanced tutorials Assignments are automatically graded with up- to-date diagnostic information, helping instructors pinpoint where students struggle either individually

of appropriate chemical demonstrations for lecture, suggestions for addressing common student misconceptions, and examples of everyday applications of selected topics for lecture use, as well

as the solutions for all the problems in the text.

Test Bank (Download

Only) for Introductory

Chemistry: Atoms

First, 5th edition

(0-321-95691-5)

¸ Supplement for Instructors

By Christine Hermann of Radford University This printed test bank includes over 1700 questions that correspond to the major topics in the text.

with contributions from Chris Bahn of Montana State University This manual includes lists of equipment and chemicals needed to perform each lab.

format for use in classroom projection or for creating study materials and tests In addition, the Instructor can access modifiable PowerPoint® lecture outlines

to highlight key points in his or her lecture Also

available are downloadable files of the Instructor Teaching Guide, the Test Bank with more than 1000

questions, and a set of “clicker questions” suitable for use with classroom-response systems.

Making chemistry accessible

Students in this course tend to be vastly diverse in terms of chemical and mathematical background

Written from an atoms first approach, the authors focus on the concepts behind chemical equations

to help students become more proficient problem-solvers Combined with a conversational tone, this text encourages mastery of conceptual understanding and quantitative skills students need to gain a deeper understanding of chemistry, rather than just memorization

1.6  Learning Chemistry with This Book   19

the Bohr Model of the atom, developed in the early 1900s More sophisticated

models of the atom exist, but many working chemists still use this model to

make predictions about their chemistry Therefore, we will go ahead and use

the Bohr Model, keeping in mind that it predicts some chemical properties

pretty well so long as you don’t push it beyond its capabilities

A common misconception is that chemistry is all math, calculations, and

numerical problem-solving In all honesty, chemistry does have that side to

thing that comes to mind is not a complicated mathematical formula Instead,

chemists use a basic set of fundamental concepts, often best represented with

images instead of mathematical equations For example, a chemist and a

non-chemist picture the concept of melting differently:

Heat

Heat Solid Liquid

Solid (order) Liquid (disorder)

Nonchemist

Chemist

These fundamental concepts and images are the tools chemists use in

answer-ing questions about matter and the transformations it undergoes Though this

book tackles the numerical side of chemistry, it focuses on the fundamental

con-cepts, illustrating them with pictures and everyday experiences Even chemists

forget mathematical expressions and memorized equations, but the

fundamen-tal concepts, stored as images in their minds, are with them all their lives

Finally, we want to give you some advice about how to use this textbook

This advice comes from our own experience (after all, we were beginning

in hand so you can take notes, draw pictures, and write down questions on

points you are not sure about We have done three things to encourage you to

do this First, each chapter includes a number of WorkPatches marked with a

stop sign When you reach one of these, stop reading and try to do the

prob-lem or sketch the concept Don’t go on until you can answer the question Check

your answer against the answer given at the end of the chapter

New! Learning Outcomes

each chapter ends with a section of Learning Outcomes, correlated to the end-of-chapter problems the Learning Outcomes consist

of goals and skills the student should learn and practice before moving on to the next chapter.

Have You Learned This?    65

As we said earlier, you can’t avoid the numerical side of chemistry if you

hope to study it in any detail This chapter has prepared you for dealing with

this numerical side, and it is important However, the fundamental concepts

remainder of this book are just as important, if not more so After all, you

can’t use the mathematical tools you just learned about to solve a problem

until you understand what the problem is about

Algebraic manipulation (p 58 ) Energy (p 61 )

Joule (p 61 ) Law of conservation of energy (p.  61 )

Specific heat (p 62 ) Bomb (p 63 ) Calorimeter (p 63 )

Have You Learned This?

2.1 Numbers in Chemistry— Explain what an exact number is and what a measured number is [55, 56]

Precision and Accuracy Describe the difference between precision and accuracy [57, 58, 59]

2.2 Numbers in Chemistry— Explain why measured numbers always have uncertainty associated

Uncertainty and Significant with them [61, 62, 63, 65]

Figures

2.3 Zeros and Significant Identify leading zeros and trailing zeros in a measured number [64, 66, 67]

Figures Identify the amount of uncertainty in a written measured quantity [63, 68, 69]

2.4 Scientific Notation Convert a number from standard to scientific notation and vice versa

[71, 75, 173, 182]

Identify the degree of uncertainty in a number written in scientific notation

[72, 74, 75fg]

2.5 How to Handle Significant Correctly add or subtract numbers according to the rules of significant

Figures and Scientific figures [77, 80acd, 161ad]

Notation When Doing Math Correctly multiply or divide numbers according to the rules of significant

2.8 Doing Calculations in Convert the units of a measured quantity to some other units using unit

Chemistry—Unit Analysis analysis [102, 107, 110]

Learning Outcomes for Chapter 2

Advantages of an Atom’s First Approach:

•    starts at the very beginning,  providing a solid foundation;

building up material from the

“bottom-up”

•   first discusses atoms—history, their  electronic structure, the modern model of atoms and then moves on

to chemical bonding and molecules.

Students often ask, "When will I use this?" and have difficulty relating chemistry to real topics or events

in everyday life russo and Silver’s text includes various real-world applications and learning tools, placed strategically to boost interest and help students develop essential study skills as they assess their own progress

Making chemistry manageable

and relevant with practical study tools

22    Chapter 1  What Is Chemistry

1.1 Science and Technology Describe the difference between science and technology [17, 19, 65]

1.2 Matter Define the types of mixtures in terms of the types of matter [23, 24, 25, 26]

Describe how an elemental substance differs from a compound [35, 37, 38]

Explain what a chemical formula is (what it tells you) [40, 42, 43]

1.3 Matter and Its Physical Name the states of matter and the types of physical transformation.

Transformations [44, 45, 47, 48, 53]

1.4 Matter and Its Chemical Explain what happens to a substance or substances after they

Transformations undergo a chemical change [56, 57, 55, 58, 88]

1.5 How Science Is Done—The Describe the parts of the scientific method and how they are related to

Scientific Method each other [59, 60, 61]

Learning Outcomes

Concept Questions

1 Which of the following statements is true

regarding science and technology?

(a) They are completely unrelated

(b) Technology precedes science

(c) Science precedes technology

(d) Science is the application of technology

2 Matter can exist as which of the following?

(a) As a homogeneous mixture of substances

(b) As a pure substance

(c) As a heterogeneous mixture of substances

(d) As all of the above

3 To be a compound, a substance must

(a) be made from more than one type of element

(b) not be a mixture

(c) be homogeneous

(d) be all of the above

4 An elemental substance

(a) can also be a compound

(b) can never be a compound

(c) cannot participate in a chemical reaction

(d) cannot change state since it is a pure element

5 When a pure substance melts, it

(a) undergoes a chemical change

(c) for the same change of state

(d) chemical properties of the substance

7 A chemical property of hydrogen is that it (a) is a gas at room temperature

(b) is odorless

(c) combines with chlorine to make the compound hydrogen chloride (HCl)

(d) combines with air to give a mixture of hydrogen and air

8 In a chemical reaction (a) a physical change takes place

(b) products are converted into reactants

(c) one or more substances are converted into different substances

(d) elemental substances change into different elements

9 A law is explained by (a) experimental data

is fact

(b) a theory is an untested hypothesis

(c) a theory is a well-tested hypothesis

(d) a theory is never wrong, whereas a hypothesis may be wrong

Intermolecular Forces and

the Phases of Matter

In Canada’s Northwest Territories during the winter months, “ice-road truckers” drive

their big rigs over the surface of frozen lakes on what are known as ice roads These

roads service mines are the only way to get goods in and out during the winter Trucks

hauling more than 40 tons ply these roads day and night

The average thickness of the ice is 125 cm (a little over 4 feet thick), but the

ice road can be opened for travel at 22 cm (8.7 inches) thickness, and still it supports

can set in, driving hundreds of miles on ice against the white landscape, but it never

soned veterans forgo seatbelts because if the surface gives way, a trucker will have

just seconds to jump clear

The only thing between the driver and certain death are the tenacious attractive

forces that exist between the water molecules in the ice Why do water molecules

at-tract one another? Read on

I t’s the middle of July, 34 °C, and you feel as if you’re covered with a wet

blanket Sound familiar?

These are the sweltering, high-humidity days of summer when there is just

too much water in the air You can’t see this water because it exists in the gas,

or vapor, phase, but you can certainly feel it It makes you feel miserable

Today’s solution to this problem is, of course, the air-conditioner, which cools

the air by drawing it in with a fan and passing it over cold refrigeration coils

they are dripping wet Cooling humid air causes the water vapor in the air

to condense to a liquid on the cold coils, and in this way the air is dried as it is

“conditioned.” This is why air-conditioned air feels so good on a humid

sum-mer day—it’s not just cooler, it’s also drier By setting an air-conditioner on its

highest setting, you can sometimes cause the refrigeration coils to get so cold

that the liquid water on them freezes Thus, simply by cooling the air, an

air-conditioner can drive atmospheric water through three phases—from the gas

phase through the liquid phase and into the solid phase 3.7  An Introduction to Ions and the First Ionization Energy   107

was the hint for such a model

to be found? Believe it or not, the hint came from examining light Not just any light, but light given off when atoms of elements in the gas state were provided with large amounts

of energy You are looking

at such light every time you read a neon sign Neon lights are glass tubes filled with neon gas atoms that give off a characteristic orange-red light when supplied with electrical energy Bright yellow light is given off by sodium-vapor street lamps Even a tube filled with hydrogen gas glows bluish-pink when electrified

Being of a curious nature, physicists passed this light through a prism Passing light through a prism was nothing new Sunlight (so-called white light) passed through a prism is separated,

or dispersed, into its component colors Drops of water in the atmosphere acting like

prisms have given all of us a chance to see this dispersion in the form of a rainbow.

A rainbow created from white light is called a continuous spectrum because the

col-ors smoothly blend into one another without any breaks.

But look at what happened when physicists passed the light given off by a hydrogen or neon lamp through a prism They saw separate lines of color (first detected for hydrogen by scientists in the mid-1800s) We must tell you that this was astounding! Never before had such a thing been observed These are called

either discontinuous spectra or line spectra because the colored lines do not blend

smoothly into one another Instead, there are regions of blackness between lines.

400

(wavelength in nm)

500 600 700 400

Ne H

(wavelength in nm)

500 600 700

Prism Prism Line Spectra of Hydrogen and Neon

Line spectra were the hint for an improved model of the atom, one that could link periodicity to atomic structure To understand this hint, we are

Line Spectra of Hydrogen and Neon

Real-World Applications

applications are woven directly into the text’s

conversational narrative, evoking powerful

images in students’ minds and helping them

grasp and retain concepts examples from

areas such as nutrition and the atmosphere and

including specific examples related to DNa

modification and corrosion show that chemistry

is a fascinating science.

Section-Level Applications

Compelling applications and vignettes also appear as appropriate at the section level throughout the text.

New! Concept Questions

asking students to think a bit further, these questions were written to gauge level of understanding and encourage students to review and apply the important concepts of

a specific chapter.

Math Review

MasteringChemistry offers a variety of math remediation options for students to brush up on required quantitative skills including both Math review tutorials that can be assigned as prerequisites before moving onto more difficult material and Math remediation tutorials that offer just in time help to specific students based on their individual answer inputs these exercises include guided solutions, sample problems, and feedback when students answer incorrectly.

MasteringChemistry is the most effective, widely used online tutorial, homework and assessment system

for chemistry It helps teachers maximize class time with customizable, easy-to-assign, and automatically

graded assessment that motivate students to learn outside of class and arrive prepared for lecture these assessments can easily be customized and personalized by teachers to suit their individual teaching style to learn more, visit www.masteringchemistry.com

personalized coaching and feedback

Student Tutorials

tutorials have been adapted and authored by an advisory board of expert chemists who teach with the atoms first approach Immediate feedback helps students develop the problem-solving skills and motivation needed to succeed in this course.

New! WorkPatch Hints

Conceptual practice problems called Workpatches are now assignable in MasteringChemistry

Students who are having trouble completing a Workpatch problem can scan the Qr code on this page or visit the Study area in MasteringChemistry for hints, and then go back and try the Workpatch problem again.

92    Chapter 3  the evolution of atomic theory

Atomic Mass

We have looked closely at atomic number and mass number, but neither tells tritium 1 3 H2 is 3, the actual mass of this atom is not 3 (not 3 g, not 3 lb, not 3 anything) So, what is the actual mass of a tritium atom? The actual mass of

any atom is formally called its atomic mass.

To begin our discussion, let’s look at the atomic masses for some isotopes

of hydrogen, carbon, and magnesium The atomic masses are given in atomic

mass units (abbreviation amu).

Isotope Atomic mass (amu) Isotope Atomic mass (amu)

1 H 1.007 83 12 C 12

2 H 2.014 10 13 C 13.003 35

3 H 3.016 05 24 Mg 23.985 04

An atomic mass unit (also known as a dalton, Da) is defined as exactly

one-twelfth the mass of a 12

6 C atom and is equal to 1.660 54 * 10 -24 g:

54 10 – 24 g 1

12 6 amu = the mass of C atom 12 = 1.660 × 1

Do you notice something about the atomic masses? Look closely For all isotopes except 12 C, the atomic mass does not equal the superscript mass number, although they are close Only 12 C has a mass in amu exactly equal

to its mass number (this is due to a universal agreement by all chemists worldwide).

Because the atomic mass unit is defined this way, atomic masses are

of-ten called relative atomic masses (relative as in “compared to”) In other words,

you can think of atomic masses as telling you how massive an atom is pared to a 12 C atom For example, one 1 H atom has an atomic mass of 1.007 83 amu This means that an 1 H atom is 1.007 83 , 12, or roughly one-twelfth, as massive as a 12 C atom One 24 Mg atom has an atomic mass of 23.985 04 amu, which means that a 24 Mg atom is 23.985 04 , 12, or roughly twice, as massive

com-as a 12 C atom.

Of course, because you know how many grams 1 amu equals, you can calculate the mass of an atom in grams To see this, let’s calculate the mass in grams of one 12C atom, the only atom whose mass number and atomic mass

are equal:

12 amu 1 660 54 10–24g 1 992 65 10 – 23 g amu

some-We have one more topic to cover before we end our discussion of atomic mass We said that an atom of the 12 C isotope has an atomic mass of exactly

12 amu by universal agreement But if you take a look at the periodic table,

Calendar Features

the Course home default page features a Calendar View displaying upcoming assignments and due dates.

•   Instructors can schedule  assignments by dragging and dropping the assignment onto a date in the calendar

•   The calendar view gives  students a syllabus-style overview of due dates, making it easy to see all assignments due in a given month.

www.masteringchemistry.com

NEW! Dynamic Study Modules

these are designed to enable students to study effectively on their own as well as help students quickly access and learn the nomenclature they need to be more successful in chemistry these modules can be accessed on smartphones, tablets, and computers and results can be tracked in the MasteringChemistry ® Gradebook how it works:

1 Students receive an initial set of questions and benefit from the metacognition involved with asking them to indicate how confident they are with their answer.

2 after answering each set of questions, students review their answers.

3 each question has explanation material that reinforces the correct answer response and addresses the misconceptions found in the wrong answer choices.

4 Once students review the explanations, they are presented with a new set of questions Students cycle through this dynamic process of test-learn-retest until they achieve mastery of the material.

Gradebook and Student

Performance Snapshot

the Gradebook feature captures the

step-by-step work of each student in

class, including the time taken on every

step With a single click, charts summarize

the most difficult problems, vulnerable

students, grade distribution, and even

score improvement over the course

C h a p t e r 1

What Is Chemistry?

Congratulations! You are taking a chemistry course Chances are that you are taking it for one or more of the following reasons:

1 I have to take a science course, geology was closed, and physics is too hard

2 All my friends are in the class

3 It fits into my schedule

4 It is required for my major

There are much better reasons Read on!

It is the early part of the twentieth century, 1914 to be exact I am over-

come with grief My youngest child is burning with fever The sickness

has spread from her ear to her entire body Her skin has a scarlet look,

and she is in great pain The doctor has applied some tincture of iodine,

but he does not know how to cure her He has told us to make

arrangements My beloved child will not see her fourth birthday.

It is the early part of the twenty-first century, 2014 to

be exact My daughter was ill yesterday with an earache Our pediatrician diagnosed a streptococcus infection and administered the antibiotic amoxicillin My daughter thought it tasted good, and she is back in preschool today, completely free of fever and pain.

It is the year 2036 We have chosen to have a daughter Unlike

most of today’s parents, we will not preselect her IQ However,

we do agree with our genetic counselor that her system should be

genetically engineered so that she will be immune to all known

bacterial and viral infections.

1.1 Science and Technology

The span from 1914 to 2014 was 100 years The year 2034 is only 20 years

away The pace at which things are changing is accelerating at an lievable rate One hundred years from now will be as different from today

unbe-as today is from 500 years ago Within the punbe-ast decade, a significant tion of the genetic code for the human genome has been unraveled One hundred years ago we had never even heard of DNA; today we are clon-ing it One hundred years ago we burned coal; in less than half that time from now we’ll generate energy in fusion reactors powered by hydrogen

por-taken from seawater, duplicating the process that occurs within the cores

of stars

Change this rapid is new for humanity Until recently, each new tion could expect to live pretty much like the one before it Not anymore We scarcely have time to get used to one change before ten more are upon us We’ve barely had time to think about the ethics of birth control, a develop-ment of the 1970s, and now stem cell research, life prolongation, and cloning

genera-are knocking at our door Your personal computer and its software are almost outdated the day you buy them What is feeding all this change? The

answer is science.

The dictionary defines science as “the

experi-mental investigation and explanation of natural phenomena” or “knowledge from experience.” Science begins with a simple question, like “how?”

or “why?” How are atoms put together? Why do bats fly at night? Science is the pursuit of knowl-edge for its own sake, because we are curious But science itself can’t cause change unless some-thing is done with the knowledge it uncovers For

that we need technology, the application of

scien-tific knowledge So science is also the pipeline for technology—feeding it and supplying it with ideas For example, scientists asked “How are atoms put together?” and their experiments led them to an answer Today, technologists can use that knowl-edge to change our lives by developing nuclear medical technologies to treat cancer and by building nuclear bombs As is so often the case with scientific knowledge, it can be used to achieve very different ends

Because science feeds technology, it’s not a bad idea to ask the question “Is science always right?” Just consider these headlines:

FDA Proposes Banning Saccharin

as Carcinogen

What is going on? Isn’t science only about absolute, fundamental, provable truths? Unfortunately, no Science, like literature, art, and music, is a human endeavor And because it is a human endeavor, carried out by human scien-tists, you would not be wise to bet on science’s infallibility Ego, mistakes, and stubbornness can all get in the way of finding the truth And what about technology? Is the technological application of scientific knowledge always good? Consider some of the forces that drive technology: the desire to benefit humankind, the desire to make a profit, the desire to be stronger than our

Nuclear

medicine of Earth’s historyIsotopic dating

Science: The exploration of the structure of the atom

Technology: Applications of our knowledge about atoms

Nuclearpower weaponsNuclear

enemies Which motive do you think drives the cigarette industry in its

appli-cation of knowledge concerning the effects of nicotine?

This brings us to some very important questions Who should decide

which areas of science are explored? Who should decide if a scientific

result is real or a hoax? Who should decide what is done with scientific

knowledge? In a free society, the answer is supposed to be the collective

“you.” After all, what scientists discover and technologists put into practice

will dramatically affect how you live In addition, much of the scientific

research in this country is paid for by your tax dollars Does this mean you

have to earn a Ph.D in chemistry, biology, or physics so that you can make

informed decisions? For most people, that is not a practical or even a

desir-able solution But total ignorance of science is not the answer either,

because science and technology affect us directly in our everyday

living

This book is about the branch of science known as chemistry, often

considered the “central science” since it forms a bridge between the

principles of physics and the practice

of biology Chemistry is the study

of matter and the transformations

it undergoes (matter is being

trans-formed within the space shuttle’s

rocket engines illustrated here) To

understand this definition, we need to

focus on two key concepts: matter and transformation.

1.2 Matter

Matter can be simply defined as “stuff”—anything that has mass and

occu-pies space Some matter you can feel and see, like this book Other matter, like

the air that surrounds you, is difficult to detect, but it still exists It occupies

space (the volume of the room), and it has mass (a tank filled with helium

gas weighs more than the empty tank) Defining matter as “stuff” is adequate

for most everyday situations Since scientists often ask very specific

ques-tions, however, it almost always requires much more precise and detailed

definitions Chemists define matter by dividing it into two broad types, pure

substances and mixtures In pure substances, only a single type of matter is

present Mixtures occur when two or more pure substances are intermingled

with each other For example, table salt (chemical name, sodium chloride) is

a pure substance So is water And so is table sugar (chemical name, sucrose)

If you put salt and sugar in a jar together and shake, however, you have a

mixture Dissolve sugar in water, and you have another mixture Some things

that you might not think of as mixtures actually do fit the definition—a rock,

for example In most rocks, you’ll see a mixture of different minerals, each a

different pure substance

Chemists further subdivide mixtures into two types, homogeneous and

heterogeneous Homogeneous mixtures (homo-, meaning “the same”) are

ones in which the composition of the mixture is identical throughout

A cup of tea with some sugar dissolved in it is a homogeneous mixture

Once well stirred, such a mixture is exactly the same no matter where you

sample it

Water vaporproduced inrocket engine

Hydrogen and oxygen combine and

transform into water vapor and heat

in the space shuttle’s liquid-fueled engine, helping to propel theshuttle into space

Another name for a homogeneous mixture is a

solution Our well-stirred cup of tea with sugar is a solu-tion The air you are breath-ing, consisting of a mixture made mostly of nitrogen gas and a smaller amount of oxygen gas, is also a homoge-neous mixture, or a solution Under normal conditions, no matter where you sample the air in the room, its composi-tion (percent nitrogen and percent oxygen) is the same

The rock pictured above is an example of a heterogeneous mixture

(hetero-, meaning “different”) because its composition is not the same

through-out Sometimes, heterogeneous mixtures can appear to be homogeneous even when they aren’t A mixture of table salt and table sugar is a heterogeneous mixture even when the two substances are ground together into a fine pow-der This is true because a tiny sample taken at one place in the mixture might contain a different ratio of salt to sugar than a tiny sample taken at some other place If the amount taken is small enough, it would even be possible to get a sample from this mixture that was pure sugar or pure salt, no matter how well you mechanically ground the two together Only when such a tiny sample has the same composition wherever you sample it (as in the tea with sugar) can you call the mixture homogeneous

A precise dividing line between a heterogeneous mixture and a neous one is difficult to specify Just how uniform does a mixture have to be

homoge-in order to be considered homogeneous? Obviously, if the sample analyzed is

of atomic size and includes only one atom, then no mixture can be considered homogeneous In a larger sample containing billions and billions of atoms, the limiting factor is the analysis procedure used and how small a difference

in composition is detectable by the experiment In this text, we shall consider only obvious examples for discussion and classification and leave the more ambiguous determinations to the philosophers in the audience

WorkpaTch 1.1 Classify the following examples of matter as pure stances, heterogeneous mixtures, or homogeneous mixtures (solutions) (a) piece of wood

sub-(b) iron nail (c) rusty iron nail (d) well-stirred mixture of food dye in water (e) beeswax and candle wax mixed together by hand (f) beeswax and candle wax melted together, stirred well, then allowed to solidify •

Check your answers to WorkPatch 1.1 against the answers given at the end

of the chapter Did you get the right answers for the last two items? These items should make you think Only one of the mixtures of beeswax and candle wax represents a solution because only one of the mixing processes (melting) can produce a homogeneous mixture

Homogeneousmixture(sugar dissolved in tea)

Heterogeneousmixture(granite)

practice problems

1.1 Which of the following are solutions?

(a) our atmosphere

(b) gold powder and silver powder ground together

(c) piece of 18-karat jewelry made from melting gold and silver metals together

(d) detergent dissolved in water

(e) oil droplets suspended in water

Answer: (a), (c), and (d)

1.2 Examination of “homogenized” milk under a microscope reveals suspended globules

of fat Is milk a heterogeneous mixture or a homogeneous mixture? Explain.

1.3 Fog is a suspension of tiny droplets of water in air Is fog a heterogeneous mixture or

a homogeneous mixture? Explain.

Before leaving the definition of matter, we want to say something about what

matter is made of All the matter that exists on our planet—from the air, to the

dust in the air, to the ground we walk on, to the water that covers most of the

planet, to the lifeforms that live on it—is made from elements, which are the basic

building blocks of matter At the time of writing, there are 118 known elements,

90 that occur naturally and 28 that can be synthetically prepared All the known

elements have been organized in a tabular form known as the periodic table.

The periodic table is so important to chemistry that we shall devote most of

Chapter 3 to it (A more complete periodic table and a list of the full names of

all the elements appear inside the front cover of this book.)

Lu

174.967

262

71 89

Many elements have names that you are probably quite familiar with— carbon, silver, gold, iron, aluminum, uranium, hydrogen, helium, oxygen, and nitrogen are a few Chemists represent the elements with one-, two-, or three-letter symbols (as shown in the periodic table), some taken from the English names (like C for carbon, H for hydrogen, and Al for aluminum) and others taken from the Latin names (like Fe for iron from the Latin word

ferrum ; Au for gold from the Latin word aurum) or other languages.

When we say that elements are the basic building blocks of matter, how basic is basic? For example, suppose you had a piece of pure elemental gold What would happen if you cut the piece of gold in half, and then in half again, and then again, and then again? How many times could you divide the piece and still have elemental gold? People have been trying to answer this question for centuries Around 400 B.C., the Greek philosopher Democritus suggested

an atomic theory of the universe Simply put, this theory said that all things

are made up of minute, indivisible, indestructible particles called atoms That

this might be true was by no means self-evident A piece of gold does not appear to be made of individual particles Nevertheless, Democritus would have said that you can keep dividing your piece of gold only until you get down to a single atom of gold In fact, Democritus was right, but his theory was not an easy sell Aristotle, another Greek philosopher living around the same time, placed more trust in his senses and said that matter was continu-ous and not made up of discrete individual atoms According to Aristotle, you could keep dividing your gold into smaller and smaller pieces forever; at

no point would you reach an indivisible particle Because Aristotle’s tion seemed more obviously correct, his theory carried the day for more than

proposi-2000 years

As you will see in Chapter 3, scientists did eventually return

to the atomic theory We now know that all the elements exist as

atoms, and an atom is the smallest possible piece of an element

Atoms are so tiny that, until recently, scientists thought we would never be able to see them They spoke too soon Though no one has seen an atom through an ordinary microscope, in the early 1980s,

a device called a scanning tunneling microscope produced the first images of individual atoms—like the silicon atoms that appear as purple spheres on the surface of the silicon crystal shown in the photograph at left

With the knowledge that matter is made up of atoms of the

elements, we can now divide pure substances into two types, mental substances and compounds An elemental substance is one

ele-that is made from atoms of just one element For example, our piece of pure gold is made from just gold atoms and nothing else The same is true of a piece of pure iron (or any other pure metal), the oxygen you breathe, and the helium gas in a balloon

Compounds, on the other hand, are pure substances made from atoms

of two or more different elements Water, for example, is a compound made

from atoms of hydrogen and oxygen A chemical formula for a compound

indicates the number of atoms of each element that make up the smallest sible piece of that compound The chemical formula for water, H2O, tells us that the smallest possible piece of water is made from two hydrogen atoms and one oxygen atom Because water is made from two different elements, it

pos-is classified as a compound So pos-is table sugar, whose formula pos-is C12H22O11 The oxygen in the air you breathe is a different case The formula for oxygen, O2,

An image of silicon taken with a

scanning tunneling microscope Each

purple sphere is a silicon atom

tells us that the smallest piece of life-sustaining oxygen gas has two oxygen

atoms in it However, though oxygen is made from two atoms, both are atoms

of the same element, and so oxygen is not considered to be a compound;

oxygen is an elemental substance To summarize:

Homogeneous mixture(solution): composition isuniform throughout

Heterogeneous mixture:

composition is notuniform throughoutPure substance Mixture

Gold Water Sugared tea Marble

Classifying matter according to this scheme

sometimes requires careful examination Consider,

for example, a glass of water, a glass of lemonade

made from a powdered mix, and a glass of

lemon-ade mlemon-ade from freshly squeezed lemons

The water is a pure substance and a compound

The lemonade made from the mix is a

homoge-neous mixture (a solution) The lemonade made

from lemons is a heterogeneous mixture because of

the lemon pulp bits floating in it

practice problems

1.4 Which of the following are compounds?

(a) iron oxide 1Fe2O32

(b) ozone 1O32

(c) iron (Fe)

(d) carbon monoxide (CO)

(e) propane 1C3H82

Answer: (a), (d), and (e) because each is made from more than one kind of element;

(b) and (c) are elemental substances, not compounds, because each is made of only

one element.

1.5 Which of the following are compounds?

(a) sulfur 1S82

(b) mixture of iron powder and aluminum powder

(c) mixture of O2 gas and N2 gas

(d) sulfur dioxide 1SO22

(e) ammonia 1NH32

1.6 True or false? A compound is a pure substance, but a pure substance need not be a

compound Give examples to prove your answer.

Pure water Lemonade from

powdered mix Lemonade from freshly squeezed

lemons

1.3 Matter and Its physical Transformations

Let’s get back to the definition of chemistry, which is why we started looking

at matter in the first place We said that chemistry is the study of matter and

the transformations it undergoes Since transformation means “change,” istry is the study of changes in matter And just as the word matter had to be

chem-subdivided into pure substances and mixtures, we must be very careful with

the word change In the science of chemistry, there are two kinds of changes matter can undergo: physical and chemical.

A physical transformation of a pure substance is one that leaves it as the same

substance but in a different physical state This leads us to another question: What

do we mean by a state of matter? You are already familiar with the three most

common states of matter: solid, liquid, and gas (or vapor) We shall examine

these states in a detailed way later in this book, but for now your common edge of them will do just fine Let’s use water to demonstrate physical changes

knowl-in matter If you put a glass of liquid water knowl-in a freezer, the water will change to

the solid state in the process we call freezing This is an example of a physical

change because only the state of the substance has changed It’s still water after

the change The reverse of freezing, called melting, is another example of a

physi-cal change Naturally, the temperature below which liquid water freezes is also the temperature above which solid water melts, 32 °F or 0 °C at normal atmo-spheric pressure (The Fahrenheit and Celsius temperature scales are described in Chapter 2.) Thus, this temperature is called either the freezing point or the melt-ing point of water, depending on which way you are going When heated either

to or above its boiling point (212 °F or 100 °C at normal atmospheric pressure),

water boils and undergoes vaporization, the change from the liquid to the vapor state In the reverse of vaporization, condensation, the vapor returns to the liquid

state After either change, we still have water, and so vaporization and tion are two more examples of physical changes

condensa-0 °C: the meltingpoint and freezingpoint of water

100 °C: the boilingpoint and condensationpoint of water

Water melts when its temperaturegoes above 0 °C; it freezes when itstemperature goes below 0 °C

Water boils when its temperature

is 100 °C; it condenses when itstemperature goes below 100 °C

The melting point and boiling point of water are among its physical

prop-erties The physical properties of a pure substance characterize its physical

state and physical behavior Other physical properties of water include its

1.3  Matter and Its Physical Transformations   11

color (pure water is colorless), its odor (pure water is odorless), and its taste

(pure water is tasteless) The following table summarizes some of the physical

properties of water:

Physical Properties of Pure Water (at Normal Atmospheric Pressure)

Melting point 0 °CBoiling point 100 °CColor NoneOdor NoneTaste None

Each pure substance has its own unique set of physical properties For

example, pure ethanol, the component of beer and wine that gets you drunk,

is a colorless liquid that looks just like water However, it melts at -117 °C

and boils at 78 °C Thus, if you are presented with a colorless liquid and asked

to determine whether it is water or ethanol, you can place a thermometer in

it and heat it to boiling If the thermometer reads 78 °C when it boils, then the

liquid is ethanol

Another important physical change is sublimation, which occurs when

a pure substance goes directly from the solid state to the gas state without

passing through the liquid state For example, when you heat an ordinary

ice cube, it first melts to liquid water before boiling to enter the vapor state

Carbon dioxide, however, another pure substance, behaves quite differently

Carbon dioxide exists as a solid below -78 °C, but if you warm it above this

temperature, it slowly vanishes into thin air without ever forming a puddle

or displaying any obvious wetness (For this reason, solid carbon dioxide is

called “dry ice.”) It goes directly from the solid state to the gas state—it

sub-limes Unlike water, carbon dioxide cannot exist in the liquid state unless a

great deal of pressure is applied to it

at 100 °C, and so it isprobably water

Dry ice sublimes Ice melts

At room temperature (25 °C):

°C

It is even possible for regular ice (solid water) to sublime if conditions are right Have you ever noticed how snow disappears even when the tempera-ture remains below freezing? The same thing happens inside the freezer com-partment of a frost-free refrigerator

Ice sublimes

(Have youever noticedhow ice cubesslowly vanish

in yourfreezer?)

At freezer temperature(below 0 °C):

One monthlater

Answer: (d); the ice cubes “vanish” by going directly from the solid state to the gas state.

1.8 Molten iron cooling to solid iron is an example of (a) sublimation

(b) condensation (c) freezing (d) melting

1.9 True or false? After being heated to above its boiling point, ethanol is no longer ethanol but something else Explain.

1.10 You are presented with a block made of some pure metal and told the metal is gold, but you have your doubts Using a thermometer, how can you determine whether the metal is gold?

1.4  Matter and Its Chemical Transformations   13

1.4 Matter and Its chemical Transformations

So far, we have been concentrating on the physical changes and physical

properties of pure substances It’s now time to switch to chemical changes and

chemical properties of pure substances A pure substance is said to have

under-gone a chemical change (chemical transformation) if, after the change, it is a

different substance or substances For example, if you combine appropriate

amounts of hydrogen gas, a pure substance, with oxygen gas, another pure

sub-stance, and then supply a spark, a new substance—water—will appear, and the

hydrogen and oxygen will be gone The hydrogen and oxygen have undergone

a chemical change The chemical properties of a pure substance are properties

that can be described only when it undergoes a chemical change For example,

color isn’t a chemical property because the color of a substance is apparent

without any need to change it chemically in order to make this determination

Flammability, on the other hand, is a chemical property because burning a pure

substance converts it into an entirely different substance or substances For

example, hydrogen is considered to be a flammable gas Reactivity is a chemical

property of a substance that describes the ability of a pure substance to undergo

chemical change when combined with other pure substances For example,

helium gas is considered nonreactive because, when combined with other

sub-stances, no chemical change occurs Chlorine (a greenish gas having the formula

Cl2) is considered to be very reactive because it combines with most substances it

comes into contact with to create new substances An exciting example of

chemi-cal change is the combination of chlorine gas with sodium (a soft, shiny metal

having the elemental symbol Na, from the Latin natrium) If you mix sodium

and chlorine together, a rather incredible thing happens A tremendous amount

of heat and light is given off When things calm down enough for us to take a

look, we see that the sodium metal and chlorine gas are both gone, replaced by

an entirely new pure substance, the compound sodium chloride (formula NaCl):

Sodium metal

(Na)

Chlorinegas(Cl2)

Chemical transformation Table salt(NaCl)

The new compound has chemical properties entirely different from those

of either of the pure substances from which it was made It no longer is lic, like sodium, and it no longer burns things it comes into contact with like

metal-chlorine It’s ordinary table salt What you have witnessed is a chemical formation As we said, a chemical transformation occurs when new substances, having new physical and chemical properties, are formed from some starting

trans-substance or trans-substances The starting trans-substances are called reactants, and the new substances formed are called products The process that goes on during the conversion of reactants to products is called a chemical reaction.

Chemists write chemical reactions using a symbolic representation, with the reactant substances to the left of a horizontal arrow and the product sub-stances to the right The arrow itself means “react to give.” For instance, a chemist would write the chemical reaction between sodium and chlorine as

2 Na + Cl2 2 NaCl

In English, this says “sodium and chlorine react to give sodium chloride.” The matter has undergone a chemical transformation Often, chemists include

the notation (g) for gas, (l) for liquid, or (s) for solid to represent the physical

state of each substance in a reaction Thus, we could have written

2 Na1s2 + Cl21g2 S 2 NaCl1s2

Most chemical transformations are carried out by nature, not by chemists The rusting of iron, be it in a nail or on your car, is a chemical transformation in which iron reacts with oxygen in the presence of water to give the new compound, a hydrate of iron(III) oxide (formula Fe2O3#H2O), commonly known as rust.

Even more important to humans are the chemical tions that occur during the digestion of food Some of the food you eat gets converted to carbon dioxide and water, which you exhale Your very thought processes involve many chemical reactions

transforma-In spite of the stereotype of the crazed scientist madly mixing test tubes of chemicals for the joy of it, that’s not the reason chem-ists mix substances together Chemists are constantly searching for new compounds with new chemical and physical properties that can extend our knowledge about how matter behaves and can benefit humankind New compounds to combat disease, to protect metal from corrosion, to whiten and brighten socks—the list goes

on and on Chemical transformation is what makes chemistry so interesting and worthy of study

Chemistry got its start hundreds of years ago in the medieval period Back then, alchemists, the forerunners of modern-day chemists, were busy trying to turn base metals, such as lead, into gold They didn’t succeed, but what they discovered while trying laid the foundation for the science of chemistry Today we know that the alchemists could never have succeeded, for while turn-ing lead into gold is an example of transforming matter from one

substance into another, it is not an example of a chemical

trans-formation In a chemical transformation, none of the elements in the reactants change If your reactants have carbon, hydrogen, and oxygen in them, then your products must have only carbon, hydrogen, and oxygen in them and no other elements A chemical

1.5  How Science Is Done—The Scientific Method   15

transformation can’t convert one element to another element, and so turning

lead into gold by chemical means is impossible (Modern-day scientists can

turn lead into gold via a nuclear transformation, which converts one element to

another; you’ll learn more about this in Chapter 16.)

practice problems

Refer to the periodic table inside the front cover for names of elements not yet familiar

to you.

1.11 Which of the following represent a chemical transformation?

(a) 4 P1s2 + 5 O21g2 S 2 P2O51s2

(b) H2O1g2 S H2O1l2

(c) 3 O2 S 2 O3

Answer: (a) and (c) because the products are different from the reactants; (b) is a physical

change because we have water on both sides of the arrow.

1.12 Water 1H2O2 and carbon dioxide 1CO22 are produced in a chemical reaction when

methane 1CH42 and oxygen 1O22 are combined and heated Which are the reactants,

and which are the products?

1.13 What, if anything, is wrong with the following chemical reaction?

Cl 21g2 + Br21l2 S 2 HCl1g2 + 2 HBr1g2

(a) It is not a chemical reaction It is only a physical transformation.

(b) The products include elements that are not in the reactants.

(c) There is nothing wrong with the chemical reaction.

1.5 how Science Is Done—The Scientific Method

Concepts such as what atoms are made of and how they react are essential to

our understanding of chemistry Many of the basic ideas that underlie

chemis-try were developed in the last 150 years, but the process that scientists used to

develop these concepts has been around much longer In fact, any curious person

seeking answers to a question might have, and probably has, used the scientific

method For example, consider Albert It is a commonly held belief that scientific

types have little or no romantic life This is, in fact, not true In his younger days,

Albert found himself newly arrived at a university, seeking dates

Being of a curious nature, he decided to study the topic of dating He went

on many dates, making observations, collecting data, and recording

it all in his diary (his “laboratory notebook”) These dates were

his experiments, which are procedures scientists carry out to

study some phenomenon For Albert, some dates were

suc-cessful and some were not On each date, he would vary

one aspect of his appearance (a racy new tie, a bold set of

socks, an eye patch), observe its effect on the outcome, and

diligently record the results

After several months of collecting data from many dates,

he came to the conclusion that changes in his appearance

above his neckline had great influence on the outcome of his

dates, but modifications below his neckline had little or no

effect This led him to postulate the following Law of

Dat-ing: “For a successful date, look as good as you can from the

neck up.” A law is a generalization that concisely summarizes

the outcome of a series of experiments At first, Albert thought this law a bit

odd, but after much thought, he developed a theory that explained why it was

true A theory is an attempt to explain why a law exists, and a model is some

kind of physical picture or mathematical expression of a theory He theorized that in any stressful situation between two people, they watch each other’s faces intensely for visual cues about how things are going This Stress-Induced Intense Facial Watching Theory explained the Law of Dating

The process Albert used to satisfy his ity about dating—collecting data from experiments, using it to fashion a law, and then postulating a theory

curios-to account for the law—is called the scientific method.

Although the dating scenario we used to illustrate the scientific method is tongue-in-cheek, it does pos-sess all the steps of the scientific method However, even though Albert was pleased with his procedure,

he probably should have discussed it with his advisor because he made some classic beginner’s mistakes Perhaps you noticed them The most obvious is that

he carried out each experiment (date) with a different woman As a result, his observations of what dates respond to most strongly were based on the likes and dislikes of a different person each time The only true way to make this study general would be for Albert

to go on thousands of dates with thousands of ent people in an attempt to average out their responses This dilemma is one

differ-of sampling and is very much like the problem pollsters face when they take

a pre-election poll They must be careful to interview enough people so that they include Democrats, Republicans, Independents, and all other affiliations in roughly the percentages that these groups exist in the general population Only then will the pollsters have a representative sample of the general population and a conclusion that has a chance of being correct

Working with a large enough sample is rarely a problem in chemical ies because most involve samples that contain millions of billions of atoms

stud-or molecules, and we are therefstud-ore always measuring the average behavistud-or

of very large groups Quite often, however, care must be taken to be sure the sample being analyzed is representative of the object being studied

The scientific method is a cyclical process in which scientists continuously uncover new information (data), postulate new laws, and either modify or dis-card old ones Based on these new or revised laws, theories are further tested and, if necessary, refined or completely revamped In repeatedly going through this cycle, sometimes theories and laws are proved to be wrong, and some-times they hold up This is how science is supposed to work Even the great

Sherlock Holmes knew this (from The Yellow Face by Arthur Conan Doyle):

on theory

Test prediction by doingnew experiment(s)

A cyclic process The Scientific Method

1.5  How Science Is Done—The Scientific Method   17

Actually, the first time a theory is postulated it is often called a hypothesis

and not a theory Only when the hypothesis holds up to further testing

(fur-ther cycles of the scientific method) is it elevated to theory status A theory,

then, is a well-tested hypothesis, but it can be proven to be incorrect at any

time with sufficient data Albert’s Intense Facial Watching Hypothesis may

not have held up to the scrutiny of further cycles of the scientific method and

made it all the way to being a theory If so, then perhaps Albert’s dating

prob-lems lie elsewhere

practice problems

1.14 What is the relationship between a theory and a law?

Answer: A theory attempts to explain why a law is correct.

1.15 What is the relationship between a law and experimental data?

1.16 What is good evidence that a theory is correct?

It would seem at first glance that the scientific method should guarantee

that science is always correct If only it were so simple Unfortunately (or

sometimes fortunately), this logical process is carried out by sometimes

illogi-cal, emotional human scientists Sometimes investigators believe so strongly

in a particular theory that they enter the cycle from the wrong direction and

attempt to interpret all they see in terms of their personal bias Bias is a strong

preference or inclination that inhibits impartial judgment For example, today

scientists believe that atoms are among the fundamental building blocks of

matter As we mentioned earlier, this is not a new idea Democritus was

bat-tling Aristotle over the possibility of the existence of atoms more than 2000

years ago Now we know that Aristotle, who rejected atoms, was wrong, but

we can’t be too hard on him—he had no ability to examine matter on a

submi-croscopic level The beliefs of the ancient Greeks were founded not on

verifi-able experimental evidence but on their opinions and convictions about the

natural world These personal biases can really get in the way of scientific

development Indeed, Aristotle went to his grave convinced that an adult man

has more teeth in his mouth than an adult woman As the renowned

philosopher Bertrand Russell once commented, “All Aristotle

had to do was ask Mrs Aristotle to open her mouth,” and he

would have discovered the truth

The fact that Aristotle never did look into his wife’s

mouth to check his theory—that he would not even

con-ceive of such a check being necessary—is an ideal

illus-tration of why scientists must always be on guard not

to let personal bias, ambition, politics, ideology, or

theology divert them from the scientific method

Scientists must be neutral to the point that they

are willing to throw out all they were taught and

replace it with something else if the scientific

method so demands That is not always easy It

has been observed quite often that “a new theory

in science is really accepted only when the last of

its opponents dies off.” Now, in case you are feeling

smug that we, in modern times, would never succumb

to such bias, just think “global warming.” If ever there was a phenomenon that was susceptible to bias, this is it We are not going to argue for or against global warming, except to say that some people on both sides of this issue have such a strong bias that they have essentially abandoned the scientific method and see only what they want to see In addition to human bias, sci-entific findings can also be compromised by flaws in the design of an experi-ment For example, how would you design an experiment to determine the effects of a vitamin C deficiency in humans? For ethical reasons, you can-not deprive a large group of humans of vitamin C Instead, you might use animals, but can you be sure the results you see in your animals represent what happens in humans? If you used mice or rats, for instance, you’d see no ill effects because, unlike humans, mice and rats can synthesize their own vitamin C If you used guinea pigs, on the other hand, the results would be similar to those for humans because guinea pigs, apes, and some fruit bats are the only other mammals besides humans that are unable to produce vitamin

C (We know what happens to humans deprived of vitamin C because the symptoms were once common during long sea voyages, before sailors learned

to carry foods containing vitamin C.)You might think chemical experiments would be less prone to flaws, but that’s not always so One source of trouble is that we usually can’t observe atoms directly To figure out what is happening on the atomic level, we measure changes we can observe, such as color change or the absorption or

emission of heat, and then infer what must have happened to the atoms Our

inference is based on how we think the observed changes relate to changes occurring on the atomic level If our understanding of this relationship is cor-rect, our conclusions are likely to be correct If our understanding is incom-plete, however, our conclusions may be wrong

Without the ability to gather data and do experiments, you can’t employ the scientific method For this reason, Democritus was unable to support his original atomic theory In contrast, some of the most beautiful examples of the application of the scientific method and the replacement of old theories with new ones come from the development of modern atomic theory, beginning with John Dalton in the early 1800s When you read about this development

in Chapters 3 and 4, keep the scientific method in mind, and you will stand why theories came and went

under-Finally we want to say a few words about models We often use models

to help us apply, understand, and visualize our theories, but you have to be careful with models By their very nature, models are incomplete representa-tions of the reality they are supposed to explain This is fine as long as you are always aware of the limitations of the particular model you are using You never want to push a model beyond its capabilities For example, consider

an airplane model glued together from the plastic pieces in a kit If it is a true scale model, then it can be used to accurately determine the wingspan of the actual plane But this type of model would never be useful in predicting the airplane’s stall speed or fuel consumption because it is “incomplete” as far as these questions are concerned For this task, you would be better served by a computer model that uses equations to calculate the thrust of the engines, the lift produced by the wings, and the drag produced by the plane’s body Of course, such a computer model is far more complicated than the plastic one and takes quite a bit more knowledge to use and correctly interpret its predic-tions Does this mean the plastic model is useless? Absolutely not, just so long

as you understand its limitations In Chapter 4, you will be presented with

1.6  Learning Chemistry with This Book   19

the Bohr Model of the atom, developed in the early 1900s More sophisticated

models of the atom exist, but many working chemists still use this model to

make predictions about their chemistry Therefore, we will go ahead and use

the Bohr Model, keeping in mind that it predicts some chemical properties

pretty well so long as you don’t push it beyond its capabilities

1.6 Learning chemistry with This Book

A common misconception is that chemistry is all math, calculations, and

numerical problem-solving In all honesty, chemistry does have that side to

it But when a chemist is presented with a question about matter, the first

thing that comes to mind is not a complicated mathematical formula Instead,

chemists use a basic set of fundamental concepts, often best represented with

images instead of mathematical equations For example, a chemist and a

non-chemist picture the concept of melting differently:

These fundamental concepts and images are the tools chemists use in

answer-ing questions about matter and the transformations it undergoes Though this

book tackles the numerical side of chemistry, it focuses on the fundamental

con-cepts, illustrating them with pictures and everyday experiences Even chemists

forget mathematical expressions and memorized equations, but the

fundamen-tal concepts, stored as images in their minds, are with them all their lives

Finally, we want to give you some advice about how to use this textbook

This advice comes from our own experience (after all, we were beginning

chemistry students once) Read each chapter slowly, with paper and pencil

in hand so you can take notes, draw pictures, and write down questions on

points you are not sure about We have done three things to encourage you to

do this First, each chapter includes a number of WorkPatches marked with a

stop sign When you reach one of these, stop reading and try to do the

prob-lem or sketch the concept Don’t go on until you can answer the question Check

your answer against the answer given at the end of the chapter