Lecture Notes for Chemistry: The Science in Context, 3rd Edition

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Chemistry: The Sciencein ContextThird EditionINSTRUCTOR’S RESOURCE MANUALwithChemConnections Activities

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Chemistry: The Sciencein ContextThird EditionThomas R. Gilbert, Rein V. Kirss, Natalie Foster, Geoffrey DaviesRein V. KirssnorThEaSTErn univErSiTywith contributing authorsSharon AnthonyTricia FerrettSandra LaursenGeorge LisenskyHeather MernitzW • W • NORTON & COMPANY • NEW YORK • LONDONINSTRUCTOR’S RESOURCE MANUALwithChemConnections Activities

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PrefaceviChapter 1|Matter, Energy, and the Origins of the Universe1Chapter 2|Atoms, Ions, and Compounds6Chapter 3|Chemical Reactions and Earth’s Composition11Chapter 4|Solution Chemistry and the Hydrosphere18Chapter 5|Thermochemistry23Chapter 6|Properties of Gases: The Air We Breathe34Chapter 7|Electrons in Atoms and Periodic Properties43Chapter 8|Chemical Bonding and Climate Change55Chapter 9|Molecular Geometry and Bonding Theories65Chapter 10|Forces between Ions and Molecules75Chapter 11|Solutions and Their Colligative Properties84Chapter 12|The Chemistry of Solids88Chapter 13|Organic Chemistry: Fuels, Pharmaceuticals, and Materials95Chapter 14|Thermodynamics: Spontaneous Processes, Entropy, and Free Energy103Chapter 15|Chemical Kinetics107Chapter 16|Chemical Equilibrium122Chapter 17|Equilibrium in the Aqueous Phase131Chapter 18|The Colorful Chemistry of Metals139Chapter 19|Electrochemistry and the Quest for Clean Energy144Chapter 20|Biochemistry: The Compounds of Life152Chapter 21|Nuclear Chemistry157Chapter 22|Life and the Periodic Table164ChemConnections Activity Worksheets167CONTENTSv

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We set out to writeChemistry: The Science in Context,Third Edition because we believe that too many studentsview general chemistry courses as collections of chemi-cal facts and algorithms to be memorized—a belief thatis reinforced by the current generation of texts. Missingfrom them are the dynamism of scientific discovery andthe connections between chemistry and the other sciences.When connections are addressed they are usually relegatedto separate chapters that most faculty do not cover, or arebriefly mentioned in boxes set off from the text, which areinfrequently read by students.Chemistry: The Science in Context,Third Edition is abook in which interdisciplinary connections form a narra-tive that spans the chapters and frames the presentation ofthe chemistry. We took this approach because students onlytruly learn chemical principles when they construct theirown meaning of them. Introducing chemical principleswithin discussions that draw from other sciences can pro-vide the desire to create meaning and the foundation fromwhich to construct it. This manual offers suggestions forintegrating the contextual material in the text and other con-textual themes into your lectures, and offers a rich trove ofactive-learning lecture resources. The sequence of chemicaltopics inChemistry: The Science in Context,Third Editionwill be familiar to anyone who has taught from a standardintroductory chemistry textbook.fEATURESOfThEinstructor’sresource manualTeaching the ContextFor each chapter, a conciseOverviewexplains the rationalebehind our selection of the chapter’s contextual framework.In it, we review the important chemical principles that arecovered and offer practical advice for presenting the mate-rial in lecture. At times we may suggest a different order-ing of the topics than that in the text because—like a statefunction—the conversations you have with your studentscan take different paths to the same end.Teaching the Contextshows how all of the conceptspresented within a chapter fit the story as a whole. Thissection also highlights key terms and provides referencesto other chapters that you can use to signal the ways thata given chapter builds upon and anticipates material fromother chapters.Sample Lecture Outlineshighlight the familiar concep-tual framework upon which the contextual story hangs andoffer a checklist of the concepts introduced in each chapter.In these outlines, each major heading takes the form of aquestion. This format mirrors the approach that we take inour own lectures and in our textbook; our goal is to helpstudents assimilate knowledge in ways that will help themmove away from excessive reliance on memorization andtoward conceptual understanding.While we have chosen to link concepts to context in away that allows us to construct an overall storyline withinour textbook, there are many other contextual avenues thatwe might have pursued for any given chapter. In fact, thespecific examples matter less than the act of making, andencouraging students to make, these connections in the firstplace. We also recognize that in lecture, some instructorswill want to use contextual examples that are different fromthose in the text.Alternative Contextssections offer sugges-tions for augmenting your own store of favorite examples.Many of these come from two books that we have found tobe rich sources of applied examples:What Einstein Told HisCook(R. Wolke) andNaturally Dangerous(J. Collman).For each chapter, we have suggested at least one alternativecontextual storyline. In some cases, the same context can becarried through several chapters.Creating a Dynamic, Student-CenteredLearning EnvironmentTheActive and Collaborative Classroom Exercisessectionof the manual offers two unique lecture resources that fur-ther develop conceptual understanding and promote activelearning: ChemTours and ChemConnections Activities.WehaveincludedclickerquestionsselectedfromMargaret R. Asirvatham,Clickers in Action(W. W. Norton)viPREfACE

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for use during lectures. This book includes severalchapterson the philosophy and application of clicker questions.Clicker questions allow for rapid testing of student under-standing of concepts during a lecture.The full set ofClickers in Actionquestions, with chapter and questionnumbers revised to reflect theChemistrytable of contents,can be downloaded from wwnorton.com/instructors.The ChemTours are designed to reinforce conceptualunderstanding through carefully developed tutorials dem-onstrating dynamic processes that help students visualizeconcepts at the molecular level. In many cases, students canmanipulate variables and observe the resulting changes toa system. Questions at the end of tutuorials guide studentsthrough step-by-step problem-solving exercises and offeruseful feedback. Students have access to a scientific cal-culator and interactive periodic table within each tutorial.Key equations and definitions are just a few clicks away.ChemTours are freely available on the StudySpace studentwebsite and are also integrated within SmartWork. Offlineversions are also available for use in lecture. Short descrip-tions of relevant ChemTours are presented in each chapterof this manual for quick reference.ChemConnections Activities, like the ChemConnectionsModules from which they are derived, are intended to helpstudents learn chemistry through active and collaborativeengagement in real-world problems that require chemis-try knowledge and scientific thinking skills. Research hasshown that students learn best when they are engaged inlearning activities that: (1) build on past experience, (2)relate what they are learning to things that are relevant tothem, (3) take part in “hands-on” experiences, (4) constructtheir own knowledge in collaboration with other studentsand faculty, and (5) communicate their results effectively.1Manyfacultyareinterestedinthisstudent-centeredpedagogicalapproachbuthavefoundthatdevelopingactivities that work well, tell a coherent story, and coverthe appropriate chemistry content is very time-demanding.That’s where the ChemConnections Modules and Activitiescome in. They cover a broad range of chemical topics andsupplyresearch-based,classroom-tested,activelearningstrategies that guide students through the scientific process.The activities in this manual include some of the authors’favorite activities from a few of the modules. They are pro-vided here as resources for instructors who wish to try outmore active methods of teaching and learning, as examplesfor instructors who wish to design their own activities, andas invitations for instructors intrigued with this style ofpedagogy to investigate the full set of ChemConnectionsModules.1How People Learn: Brain, Mind, Experience, and School.John D.Bransford, Ann L. Brown, and Rodney R. Cocking, editors. NationalResearch Council: National Academy Press, Washington, DC, 1999.Because the activities have been adapted from the mod-ules, they have been classroom tested in a form very similarto what is provided here. ThisInstructor’s Resource Manualincludesphotocopy-readyworksheetsforstudentswithintroductory text, instructions, questions, data, and spacefor notes and answers. The authors have also provided theirbest advice, as module authors and teachers, about how toguide students through these activities, and have pointedout places where you will need to make choices to adaptthem to your own students and classroom settings. Many ofthe activities are collaborative, asking students to work insmall groups to solve a problem or to make sense of data.Students benefit from group work by organizing their ideas,giving explanations, and listening to alternate or conflictingideas. The activities also include opportunities for studentsto express their understanding individually. Some of theactivities use pencil and paper while others are hands-onand may even be a little messy!When using any of the activities here, some general“good practices” should be kept in mind. Each activityshould have a beginning, a middle, and an end. The instruc-tor may set the stage by explaining the goals of the activityand introducing its logistics. During the activity, circulate tolisten to student discussions and keep students on task. Letthem struggle with the ideas a bit, even when the tempta-tion is strong to jump in and offer assistance. Help studentsvalue the group process and recognize that, in group work, athoughtful question or request for more explanation is oftenas valuable as the “right answer.” For the same reason, it isusually best not to collect the worksheets for grading; theyare intended to prompt student thinking and serve as a workspace to record ideas that are under construction. If youwish to assess student learning from the activity, choose oneof the questions from the end of the worksheet that requiresa summary or application of concepts, and have studentsprepare individual or group answers as a short in-class writ-ing assignment or as a homework problem. At the end of theactivity, take a few minutes to review the goals of the activ-ity so that students feel confident they have understood thepoint, address any issues or questions that arose, and helpstudents see how the ideas fit in with other topics recentlystudied. For more ideas on how to incorporate effectiveactive learning into classrooms, see the ChemConnectionsGuide to Teaching with Modules.Media ResourcesAdditionallecturesupportisofferedfromtheNortonInstructorResourceDiscDVD-ROMandtheonlineNorton Resource Library, which make available all theline art and tables fromChemistry: The Science in Context,Third Edition as JPEG images and PowerPoint slides, lec-ture outline slides, clicker questions in PowerPoint, andPreface|vii

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PowerPoint-ready offline versions of the approximately 100ChemTours from StudySpace.Clicker Questions fromclickers inactionEach chapter contains suggested clicker questions that havebeen selected from Margaret R. Asirvatham,Clickers inAction(W. W. Norton). The questions were chosen to reflectthe concepts introduced in the Sample Lecture Outline. Thefull set ofClickers in Actionquestions, with chapter and ques-tion numbers revised to directly reflect theChemistrytable ofcontents, can be downloaded from wwnorton.com/instructors.Suggestions for Lecture Demonstrationsand LabsTheResourcessection that concludes each chapter providesextensive references to published classroom demonstrations,and offers suggestions for laboratory exercises. We recom-mendChemicalEducationResources(CER)laboratoryexercises because we have used these experiments in ourcourses and find them to be clear and effective, with com-plete protocols, thoughtful pre- and post-lab questions, andwell-designed report formats. Each experiment descriptioncomes with comprehensive instructor’s information.ConclusionThe take-home message of this manual is that the degree towhich you align your lectures and other learning activitiesto the contexts used in the text is completely up to you. Allof us have our favorite stories and anecdotes with whichto connect our students to the principals of chemistry. Weencourage you to use yours. That way your students willhave a variety of experiences linking their personal andprofessional interests to the world of chemistry. Multiplecontexts also reinforce the message that chemistry truly isthe central science.viii|Preface

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1CHAPTER 1Matter, Energy, and theOrigins of the UniverseOvERviEwThe objective of the opening chapter is to make a case forthe relevance of chemistry in our lives and to prospectivecareers. Following this introduction, matter and energyare defined, mixtures and their separation are discussed,and the scientific method is outlined. The remainder of thechapter focuses on measurement and unit conversions. Ourapproach introduces many of these topics using substancesfamiliar to most students such as gold and water.For many students, the material in Chapter 1 is neither newnor particularly exciting. Some students are well versed in thetopics in the chapter and may be bored by the repetition of thisinformation. Others, however, are not as confident and needthe foundation presented in Chapter 1. The challenge to aninstructor is how to accommodate the needs of both groups.Our solution is to start by asking how the universe mayhave begun. Through an examination of selected observa-tions that support the Big Bang theory, we hope to catch theattention of students at all levels. For example, the residualthermal signal from the Big Bang leads to a review of tem-perature scales. We present further evidence in the form ofthe microwave afterglow of the Big Bang that was predictedin the 1940s and discovered by accident in the 1960s. Webelieve this contextual approach powerfully reinforces thecentral role of chemistry among the sciences. It also engagesthe students in an examination of the workings of the scien-tific method by using a topic with which many have somefamiliarity.A more detailed discussion of the Big Bang theoryrequires an introduction to the pioneering work of EdwinHubble in the 1920s. Hubble’s discovery that galaxies out-side the Milky Way were receding supplied evidence to sup-port the Big Bang hypothesis. To address Hubble’s evidencefor an expanding universe, we need to discuss redshifts andthe Doppler effect. While these topics are not included inChapter 1, you may wish to supplement the textbook onthese topics. A discussion of redshifts requires an introduc-tion to the wave properties of radiation and to equationsdescribing their behavior—for example,c=lnandE=hn.The fundamentals of the wave nature of light can be foundin Chapter 7, section 7.1. To challenge your audience, youmay wish to move that material forward to Chapter 1. Fora more adventurous instructor, the simple relation betweentemperature and wavelength given off by an object heatedto a very high temperature,lmax= 2.897×106nm⋅K/T,is key to understanding the microwave afterglow of theBig Bang and may prove stimulating to students who havestudied measurements and unit conversions in middle andhigh school. We believe these discussions and those of thediscovery of heterogeneities in the microwave backgroundin the 1990s add an intriguing perspective on the dynamicsof scientific discovery.With the Big Bang, we set the stage for constructingatoms from subatomic particles and work toward more-complex structures. Thus, we favor the bottom-up approach,starting with a microscopic view and building toward amacroscopic picture of matter. We hope to help studentsunderstand atomic structure before turning to the chemicalproperties of the elements and the formation of compounds.We recognize that you, the instructor, may have yourown favorite contexts within which to frame your classroomdiscussion of the traditional topics in Chapter 1. We hopeyou will use them. Additional contexts will challenge yourstudents to see the similarities between those in the bookand those presented in class. For example, one member ofthe author team uses a can of carbonated beverage to intro-duce the concepts of mass, volume, and density, as well asthe differences among the states of matter and among pureelements and heterogeneous and homogeneous mixtures.

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2|Chapter 1This context is one that every student can identify andunderstand.Chapter 1 and those that follow it include three featuresthat we hope prove useful to you and your students. EachSample Exercise is solved and paired with an unsolvedPractice Exercise. Concept Tests are intended to compel thereader to pause and provide a nonnumerical answer. As aninstructor, you might use these questions as the basis for in-class discussion. Each Sample Exercise is solved using a setof steps:Collect andOrganize,Analyze,Solve, andThink(coast) about it.coastis by no means the only effectiveproblem-solving methodology. You may have a time-testedmethod of your own. However, for the novice student,coastprovides one approach to problem solving.coastis consistently applied in the solutions toallof the SampleExercises in this textbook and to the support package.TEACHingTHECOnTExTThe opening chapter of a general chemistry textbook poses achallenge to a textbook author. Typically, the content is lighton chemistry. Certain topics such as measurement and unitconversions are unlikely to evoke an enthusiastic responsefrom students. One is often tempted just to skip this mate-rial altogether in favor of “real chemistry” in subsequentchapters. Nevertheless, given the diversity in background ofthe students, these topics must be included and discussed.What we have tried to do in Chapter 1 is to combine stan-dard introductory material with a more interesting story.Consistently throughout this book we start with obser-vations of the world around us. We see familiar objectsaround us, all of which are examples ofmatter(section 1.1).Chemistryis the science of matter. As an instructor, youmight focus on some simple examples of matter in theclassroom—some copper wire, a bottle of water a studentmay have brought to class, or a piece of gold jewelry. Ofwhat are these examples of matter composed? Matter hasmass(anextensive property) and occupies space. Allmatter is composed ofatoms(Figure 1.5). Copper wireis an example of apure substanceas well as anelement,copper, which has certainphysical propertiessuch asdensity, anintensive property. Copper is malleable, duc-tile, and has high electrical conductivity. The tarnish on thewire is achemical propertyof copper. One might even dropa little copper wire into nitric acid as a further demonstrationof the chemical properties of copper, achemical reactionthat you can describe with achemical equation. The textuses gold as an example of density determination (Figure1.20). Is the gold jewelry you wear a pure substance? Theanswer is yes only if the gold is 24 karat. [One karat is equalto 1/24 (4.17%) of the weight of the metal in a mixture.]Drop a gold ring into nitric acid—nothing happens, showingthe different chemical properties of copper and gold. Youmay need to cheat here and use a piece of cheap 14-karatgold jewelry rather than find some more expensive 22- or24-karat gold. At this point it might be useful to reveal theperiodic table of elements and locatecopper, gold, and theother 110 elements.Which element is water? This may be a silly question tonearly everyone in the audience but is one that is worth ask-ing on the first day of class. A mixture of ice and water is avery useful visual aid or prop here. Water, of course, isn’t anelement at all but a pure substance that is acompoundwithachemical formula: H2O. Water is amoleculecomposedof the elements hydrogen and oxygen. Demonstrating thatwater is composed of two gaseous elements is easy if youhave a simple electrolysis apparatus available. Connecting alarge dry cell to two pencils immersed in a beaker of wateris sufficient to illustrate the generation of hydrogen and oxy-gen. Water exists in three physical states:gas,liquid,andsolid. Boiling the water on a hot plate illustrates the conceptof water vapor. The choice of water, pre-1980 pennies, and24-karat jewelry as examples has allowed you to cover theright-hand side of Figure 1.2, a standard illustration of theorganization of matter.Why is it important to restrict our discussion to copperwire and 24-karat gold jewelry? Contemporary “copper”pennies are examples ofheterogeneous mixtures: a zinccore surrounded by a copper cladding. A 14-karat earringis ahomogeneousmixture of 58.3% Au and 41.7% Cu bymass. How would you separate the copper from the gold in14-karat gold? Here is an opportunity to combine severalobservations. We have seen that nitric acid dissolves copperbut not gold. Both metals and the homogeneous mixture of14-karat gold (alloys are defined in Chapter 12) will dis-solve in a mixture of HCl and HNO3(aqua regia, 3:1). Inprinciple, electrolysis (as for water) will deposit copper at alower potential than that required for gold. The same proce-dure is applicable to the separation of copper from zinc in apenny. Both metals dissolve in nitric acid yet are depositedelectrochemically at different potentials. It is tempting todemonstrate the etching of the copper from the outsideof a penny with acid to show the zinc core.Distillation(Figure 1.12) of the homogeneous mixture obtained by dis-solving copper in nitric acid separates the water from theionic compound copper nitrate based onvolatility. If yourestrict yourself to pennies and gold jewelry, thenfiltrationbecomes a bit trickier to illustrate. One choice is to evapo-rate the copper nitrate solution until crystals (solid) form,followed by filtration. This can be done during the lectureas part of the distillation demonstration.Copper wire and gold jewelry (assuming you did notsacrifice them to the acid treatment) provide the context fordiscussing measurement,conversion factors, the uncer-tainty inherent in all measurements, and the need to considersignificant figuresin both measurements and calculationsinvolvingexperimentaldata(section1.8).Thedensityof either object can be calculated frommeasurements ofthe mass and volume (Figures 1.19 and 1.20). In making

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Matter, Energy, and the Origins of the Universe|3each measurement, the uncertainty depends in part on theprecisionandaccuracyofeachmeasurement(Figure1.22). The calculation of density forces you to take intoaccount the number of significant figures dictated by yourmeasurements.Where did matter come from? Unknowingly, perhaps,it is a question we have all probably asked on severaloccasions in our lives. The answer to this question mayplace you, the instructor, in a delicate position of address-ing the differences amonghypotheses,theories, beliefs,and the role of thescientific method(sections 1.7 and1.10 and Figure 1.18). We present the Big Bang as anexample of a scientific hypothesis and evaluate some ofthe experimental evidence supporting this hypothesis asan illustration of the scientific method. For some students,coming to terms with the Big Bang hypothesis may proveproblematic, so we have mentioned Hoyle’s skepticism inthe same sentence as LeMaître’s hypothesis. Observationsof receding galaxies are viewed as support for the BigBang hypothesis but do not have to be presented with thisemphasis.The residual thermal signal from the Big Bang providesan opportunity to review the three commonly used tempera-ture scales,Celsius,Fahrenheit, andKelvin.SAmPlElECTuREOuTlinE(Key Terms in Italics)What are copper wire and gold jewelry composed of?matterandatomsFigure 1.2pure substanceFigures 1.3 and 1.5Clickers in Action, Chapter 1, Question 1elementphysical propertieschemical propertySample Exercise 1.1intensive and extensive propertieschemical reactionsandchemical equationsdensityEquation 1.1Which element is water?compoundsandmoleculeschemical formulaphysical states:gas, liquid,andsolidFigures 1.14 and 1.15Clickers in Action, Chapter 1, Question 6Sample Exercise 1.2electrolysisFigure 1.4Is the gold jewelry you wear a pure substance?heterogeneousandhomogeneous mixturesFigures 1.2 and 1.10How would you separate the copper from the gold in14-karat gold?distillationandfiltrationFigures 1.10 and 1.12volatilityWhere did matter come from?hypothesesFigure 1.18theoriesscientific methodHow do we know our jewelry is pure gold?unitsTables 1.1–1.3significant figuresFigure 1.19Sample Exercise 1.3Figure 1.20Sample Exercise 1.4Clickers in Action, Chapter 1, Question 9precisionandaccuracyunit conversionsFigure 1.22Sample Exercise 1.5Sample Exercise 1.6Sample Exercise 1.7Should we believe in theBig Bang?Figure 1.29Celsius, Fahrenheit,andKelvinscalesFigure 1.25Equation 1.2Equation 1.3Sample Exercise 1.8Clickers in Action, Chapter 1, Question 12AlTERnATivECOnTExTS(Key Terms Bolded)A Chemist’sview of a Soda CanWe suspect that some instructors struggle with the questionof how to make the study of chemistry seem relevant toa class of science majors from a variety of disciplines, ofwhich chemistry majors are likely to be a minority or evenabsent. One answer is to provide the students with examplesfrom the world around them. This is the basis for many ofthe science pages in magazines and newspapers as well aspopular books written for the nonscientist.While we have chosen the Big Bang and origin of theuniverse as a medium to introduce the fundamentals ofchemistry, there are many alternative contexts one couldchoose from that may be less controversial. Oneexample is tofocus on a can of soda such as Coke or Pepsi. Advertisementsfor these products abound, and there is a high probabilitythat a student in your class has brought a can of soda to thelecture. You might want to bring oneyourself. A can of sodacontains examples of all three phases ofmatter: solid,liquid,and gas. The aluminum can (excluding the paint on the

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4|Chapter 1outside) is apure substanceand an example of anelement.Aluminum is a shiny (lustrous),malleable,ductile, andelectrically conductive metal(ormetalloid), all of whichare examples ofphysical properties. How can we use a canof Coca-Cola to illustratechemical properties? Ask the stu-dents to reflect on the fate of steel versus aluminum contain-ers left out in the rain by the side of the road. Iron rusts, butaluminum does not (ignoring for the moment that aluminumwill slowly oxidize to aluminum oxide).The contents of the sealed can represent ahomogeneousmixturecontaining the ingredients listed on the label. Oncethe can is opened, the unequal distribution of the gas bubblesmakes it aheterogeneous mixture. The gas is carbon diox-ide, amolecularcompoundcontaining two nonmetallicelements, carbon and oxygen, with themolecular formulaCO2. The sodium present in the soda is, of course, not in theelemental form but is found as the sodiumcationwith someunspecifiedanionto balance the charge.How could we separate this mixture?Distillationwouldallow us to remove the highly volatile CO2as well as to sepa-rate the water from the other ingredients based onvolatility,leaving behind a mixture of molecular and ionic compounds.One could make the argument that as the volume of the solu-tion decreases, the precipitated solids can be removed byfiltration.A can of soda typically is labeled with its volume, 12 fl ozor 355 mL. This represents a fine introduction to theunitsused in measurement and serves as an example of unit con-versions. Is 12 fl oz really 355 mL? Notice that the two val-ues contain different numbers ofsignificant figures. Howdoes this affect a calculation that converts 12 fl oz to mL?Notice that the mass of the soda is not given. How could wedetermine the mass of the solution (assuming that the massof the can itself is minimal)? By weighing the can of sodawe are forced to ask about theaccuracyandprecisionofour measurement. Furthermore, with the mass of the soda inhand, we can calculate thedensityof the solution. Finally,most of us would prefer to drink our soda cold rather thanwarm. What do we mean bycold? It clearly depends onwhich temperature scale we use:Fahrenheit,Celsius, orKelvin. While 0°C might be a nice temperature for a “cold”soda, 0°F would probably leave us with a slush, and 0 Krepresents an unattainable,absolute zero. Throughout thisInstructor’s Resource Manualwe will return to the soda canas an example of an alternative context.ACTivEAnd COllAbORATivEClASSROOm ExERCiSESClickers in ActionThe following clicker questions have been selected fromMargaret R. Asirvatham,Clickers in Action(W. W. Norton)and are available atwwnorton.com/instructors. Thequestionsbelow were chosen to reflect the conceptsintroduced in theSample Lecture Outline. The chapter and question numbersrefer to PowerPoint slides fromClickers in Action.Clickers in Action, Chapter 1, Question 1Which of these atomic and/or molecular views representpure substances?A)I and IIIC)I, II, and IVB)II and IVD)II, III, and IVThis question provides visual reinforcement of thedifferences among elements, compounds, pure substances,and mixtures.Clickers in Action, Chapter 1, Question 6Dry ice sublimes at 25°C and 1 atmosphere pressure.Which equation is the correct symbolic representation forthe change that occurs?A)CO2(g)→C(s) + O2(g)C)CO2(s)→CO2()B)CO2(g)→CO2(s)D)CO2(s)→CO2(g)We will return to phase changes at several points inthe subsequent chapters; so the development of a cleardistinction between melting, boiling, and sublimation isimportant. Students are also asked to look at chemicalequations in this question.Clickers in Action, Chapter 1, Question 9In which of these measured values are the zeros notsignificant figures?I)0.0591 cmII)504 gIII)2.70 mIV)5300 LA)I and IID)I, III, and IVB)II and IIIE)II, III, and IVC)I and IVThis question asks students to remember the rules ofsignificant figures regarding zeros. This question couldalso be used to ask which number has the most significantfigures or which ones have three significant figures.Clickers in Action, Chapter 1, Question 12Neon has a boiling point of 27 K. Express this temperaturein degrees Fahrenheit.A)352°FC)–246°FB)168°FD)–411°FIn general, clickers questions requiring calculations aremore time consuming; however, students should be able totake an educated guess at the answer to this question. ByIIVIIIII

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Matter, Energy, and the Origins of the Universe|5limiting the time they have to answer the question, you canforce them to practice estimation, or the “Analyze” step ofthecoastmethod for solving problems.ChemToursThe following ChemTours are available onStudySpace(wwnorton.com/chemistry).Big BangSection 1.7, p. 18This animation explores the concept of the early formationof matter and radioactive decay rates within the context ofthe Big Bang.Significant FiguresSection 1.8, p. 21This ChemTour reviews the rules for assigning significantfigures and walks students through sample calculations. Itconcludes with a series of interactive Practice Exercisesthatrequirestudentstoexpressanswerstoaddition,subtraction,multiplication,anddivisionproblemsinsignificant figures.Scientific NotationSection 1.8, p. 21This ChemTour explains how to use scientific notation toexpress very large and very small numbers, and how to eas-ily convert back and forth between decimal numbers andscientific notation. It includes Practice Exercises.Dimensional AnalysisSection 1.9, p. 28Students learn to keep track of the units associated withnumerical values. The ChemTour includes worked examplesand interactive Practice Exercises.Temperature ConversionSection 1.10, p. 30Students practice converting between Fahrenheit, Celsius,and Kelvin temperature scales. The ChemTour includesPractice Exercises.REfEREnCESClassroomdemonstrations“Science Demonstrations, Experiments and Resources,”D. A. Katz,J. Chem. Educ., 1991, 68, 235.“Ira Remsen’s Investigation of Nitric Acid,” inChemicalDemonstrations:ASourcebookforTeachers,Vol.2,L.R.Summerlin,C.L.Borgford,andJ.B.Ealy,American Chemical Society, Washington, DC, 1988, p. 4.“TheMysteriousSunkenIceCube,”inChemicalDemonstrations:ASourcebookforTeachers,Vol.2,L. R. Summerlin, C. L. Borgford, and J. B. Ealy, AmericanChemical Society, Washington, DC, 1988, p. 15.“Sugar in a Can of Soft Drink: A Density Exercise,” inChemical Demonstrations: A Sourcebook for Teachers,Vol. 2, L. R. Summerlin, C. L. Borgford, and J. B. Ealy,American Chemical Society, Washington, DC, 1988, p. 126.“Densities and Miscibilities of Liquids and Liquid Mixtures,”D. A. Franz,J. Chem. Educ.,1991, 68, 594.“Colorful Mixture Separation,” inChemical Demonstrations:A Sourcebook for Teachers,Vol. 2, L. R. Summerlin,C. L. Borgford, and J. B. Ealy, American ChemicalSociety, Washington, DC, 1988, p. 17.“Separating Liquids: Fractional Distillation,” inChemicalDemonstrations: A Handbook for Teachers of Chemistry,Vol. 3, B. Z. Shakhashiri, University of Wisconsin Press,Madison, 1989, p. 258.“Meter Sticks in the Demonstration of Error Measurements,”R. Suder,J. Chem. Educ.,1989, 66, 437.laboratory ExercisesWerecommendthefollowingChemicalEducationResources (CER) laboratory exercises for use with thischapter. We have used these experiments in our courses andfind them to be clear and effective, with complete protocols,thoughtful pre- and post-lab questions, and well-designedreport formats. Each experiment description comes withcomprehensive instructor’s information.CER labs are published by Cengage Learning and areidentified here by title and catalogue number. Order formsand additional information about the series are availablefrom the CER website (www.CERlabs.com).CER: PROP 440, “Identifying a Liquid Using PhysicalProperties,” S. J. Melford and J. A. Anysas. Proceduresto identify the physical properties of density, solubilityin water and cyclohexane, and boiling point are followedusing a known, then an unknown, liquid. The data areused to identify the unknown.CER: PROP 627, “Observing Some Physical and ChemicalChanges in Matter,” G. W. Everett, G. W. Everett, Jr., andM. L. Gillette. Some physical and chemical properties ofselected substances are observed.CER: PROP 393, “Studying Density Using Salad Oil andVinegar,” Wendy Audrey Reichenbach. The densities ofsalad oil and vinegar are determined and compared.CER: PROP 495, “Classifying Matter by Properties,”Grover W. Everett and Grover W. Everett, Jr. Thechemical and physical properties of selected substancesare determined. The properties are used to separatemixtures of the substances.CER: MISC 521, “Using Statistics to AnalyzeExperimental Data,” Peter J. Krieger. The physicalproperties of some common objects are measured and theresulting data analyzed using statistics.

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6CHAPTER 2Atoms, Ions, and CompoundsOVERVIEWChapter 2 begins with a relatively traditional discussion ofthe pioneering work of J. J. Thomson, Ernest Rutherford, andRobert A. Millikan but with an emphasis on how experimen-tal evidence led to the currently accepted model of an atom.The concept of the scientific method (Chapter 1) showshow the interpretation of data from critical experiments wasessential to each scientist’s work.We are not unique in mentioning the contributions ofF. W. Aston to the identification of isotopes; however, wefeel it is also important to cite Aston’s work by name. Whyis this important? Surely we are not suggesting that rotememorization of names is critical to understanding isotopiccomposition—it isn’t. The message we seek to convey ishow Aston built on Thomson’s work and how it is related toMillikan’s and Rutherford’s contributions.At this point we examine some of the simple compoundsin Earth’s crust and atmosphere. Discussing composition andchemical properties of matter creates the need to cover theconventions used to name compounds. We have chosen com-pounds found in the crust or present in the early atmosphereto illustrate the rules of nomenclature. Clearly, you couldsubstitute your “favorite” compounds during classroom dis-cussions. You might take a consumer chemistry approach, aswe have done with some of our illustrations. (A few of theseproducts are also featured in Chapter 4.) Additional informa-tion on the chemistry of consumer products can be found in1001 Chemicals in Everyday Products, 2nd ed., by Grace RossLewis (Wiley, 1999). Given a model of the atom, the shape ofthe periodic table begins to make sense, as we show studentshow elements in a group form ions with the same charge.(Electronic structure is not introduced until Chapter 7.)We end the chapter by addressing the process by whichelements are made in stars: nucleosynthesis. This sectioncloses the circle by explaining the statements in the finallines of Chapter 1, namely, how elements were created.Although we strongly urge you to teach the section onnucleosynthesis, section 2.9 may be used at your discretion.If the academic calendar dictates that it is time to move onto Chapter 3, failing to cover the story of nucleosynthesiswill not harm students’ ability to comprehend the conceptsin subsequent chapters. You can even return to section 2.9,iftimeallowsyou,whenteachingnuclearchemistry(Chapter 21).TEACHING THE CONTEXTIn our years of teaching general (introductory) collegechemistry, we have observed that students are generallywell versed in the overall structure of the atom. As early asmiddle school, they learn that atoms consist of a nucleus,which contains the protons (atomic number) and neutronsand which is surrounded by the electrons. The periodictable is based on atoms having different atomic numbers.Variability in the number of neutrons (forming isotopes)is discussed in secondary school chemistry classes. For anaverage student this foundation is quite solid. The names forcompounds and ions, however, have probably faded fromtheir short-term memory. These observations are relevantbecause these concepts constitute the bulk of Chapter 2.Why should an average student pay attention to lectures onatomic structure when he or she already knows it? This isthe challenge to all instructors: how to make the materialin this chapter new and relevant. Clearly, there are manyapproaches. We propose one solution: use the historicaldevelopment of atomic structure to illustrate the applicationof the scientific method. By engaging students inhowweknow about atomic structure, as well as inwhatwe know,

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Atoms, Ions, and Compounds|7we challenge them on a different level from their prior expe-riences with chemistry.How and when did scientists first discern the commonlyaccepted picture of an atom? The notion of an atom as“plum pudding” (Figure 2.4) is just over 100 years old.Within five years of the publication of his model, J. J.Thomson’s concept of atoms as a sea ofelectronsdottedwithprotonshad been replaced by Rutherford’s model ofa nuclear atom surrounded by the electrons (Figure 2.7).Our current understanding of atomic structure developedin slightly more time than it will take the average studentin your class to graduate from college. We believe that thenotion of a five-year window of discovery will be moremeaningful to a student than the knowledge that these dis-coveries were made between 1904 and 1909. One hundredyears is way too long ago for all but a smattering of historybuffs in your audience to appreciate.HowdidRutherforddisproveThomson’smodel?Starting from Thomson’shypothesisand harnessing theworkofBequerelandtheCuries,inadditiontohisown results on radioactivity, Rutherford and his studentsdesigned theexperimentshown in Figure 2.6 that showedThomson’s model to be in error. Rutherford did not workin a vacuum. He applied the scientific method to theproblem by building on the work of other scientists insynthesizing a new explanation for a structure of the atomthat was more consistent with the data. Among the otherscientists whose work Rutherford needed was Thomsonhimself. Thomson had been the first to demonstrate theexistenceofelectrons(cathoderays)assubatomicparticles, and Millikan had established the charge on anelectron that allowed the calculation of its mass. Studies ofatomic structure did not end with Rutherford’s experiment;a significant amount of mass in atoms was still “missing”;the mass of the protons and electrons did not add up to theknownatomic massof the atom! Additional experimenta-tion by James Chadwick was needed to prove the existenceofneutrons, while Francis Aston showed that atoms ofthe same element could exist asisotopeswith the sameatomic numberbut a differentmass number. Thenatu-ral abundanceof different isotopes underlies the conceptof anaverage atomic massfor elements in the periodictable. All of this work spanned only a couple of decades,a fraction of a scientist’s working life. Your students mayappreciate the time frame of these discoveries more thanthe actual dates when the experiments were conducted.Your class may find it interesting to know that Rutherfordstudied under Thomson while Aston and Chadwick wereboth Rutherford’s students!Carbon dioxide provides an example of the law ofdefinite proportions, introduced in Chapter 1. Compoundssuch as SO2and SO3that contribute to acid precipitationmake excellent examples of thelaw of multiple propor-tions. The introduction of nomenclature andchemicalandmolecular formulasforbinary molecular compoundssuchasCO2,SO2,SO3,NO,andNO2heldtogetherbycovalentbondsfitsneatlyintothediscussionofatmospheric molecules.An example ofbinary ionic compoundsis salt (Figure 2.6),composed of sodiumcationsand chlorideanions. Studentsare all familiar with salt as a flavoring ingredient and inseawater. Consider the many possible compounds found inevaporated seawater besides sodium chloride. Thealkaliandalkaline earth metalhalides (mostly chlorides) repre-sent the most prevalent compounds. Lower concentrationsof ionic magnesium and calcium compounds are also pres-ent in such evaporites, including those withpolyatomicionsandoxoanions(Tables 2.3 and 2.4). Earth’s crust isalso rich in compounds oftransition metalslike iron andmanganese, in which the metal cations often have a rangeof charges.The general shape of the periodic table has been knownfor some 140 years. Dimitri Mendeleev’s periodic table(Figure 2.10) was based on reactivity patterns of the knownelements organized bygroupsandperiods. Differencesamong the physical and chemical properties ofmetals,nonmetals,semimetals (metalloids), andnoble gaseshadbeen documented well before anyone had a clear idea of thestructure of an atom.Where do the elements come from? While most studentshave seen the periodic table of the elements before enteringcollege, few will be aware ofnucleosynthesis, the forma-tion of the elements by nuclear processes in stars. Section2.9 provides a nice answer to the question left unanswered atthe end of Chapter 1: How did the Big Bang lead to differentelements? At the end of Chapter 2, students are capable ofunderstanding the basic nuclear reactions (fusion,neutroncapture, andβdecay) that account for synthesis of manyelements in stars, including our sun. It is unlikely that manywill have studied this in earlier courses, and we hope theywill deepen their appreciation for the importance of atomicstructure. After all, without the understanding of atomicstructure developed by Rutherford and his peers early in thetwentieth century, nuclear processes and the stellar nucleo-synthesis hypotheses could not have followed some 20 to30 years later.For your students, accepting that the origins of allmatter can be traced to the Big Bang should seem likea giant leap of faith. What evidence is there to supportthis hypothesis? Some of the evidence was presented inChapter 1. Whether a student truly accepts the Big BanghypothesisdoesnotaffecttheobservationthatEarthis constructed from compounds of some 82 naturallyoccurring elements.

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8|Chapter 2SAMPLE LECTURE OUTLINE(Key Terms in Italics)How do elements differ? What is the structureof an atom?plum pudding model (Dalton)Figure 2.4cathode raysandelectronsFigure 2.2subatomic particlesaparticlesbparticlesRutherford–Geiger–MarsdenexperimentFigures 2.6 and 2.7protonsandneutronsTable 2.1isotopesFigure 2.8atomic numbermass numberClickers in Action, Chapter 1, Question 4Sample Exercise 2.1natural abundanceandaverage atomic massSample Exercise 2.2What does the periodic table tell us?Mendeleev’s periodic tableFigure 2.10periodsandgroupsmetals, nonmetals,andmetalloidsFigure 2.11noble gasesSample Exercise 2.3Clickers in Action, Chapter 2, Question 13What happens when we combine elements?law of multiple proportionsSample Exercise 2.4binary molecular compoundsFigure 2.15molecular formulaTable 2.2Sample Exercise 2.5Sample Exercise 2.6binary ionic compoundsFigure 2.16Sample Exercise 2.7Table 2.3Clickers in Action, Chapter 2, Question 21alkali metalsalkali earth metalscationsandanionsFigure 2.17empirical formulabinary compounds oftransition metalsSample Exercise 2.8polyatomic ionsandoxoanionsTables 2.3 and 2.4Sample Exercise 2.9Sample Exercise 2.10Clickers in Action, Chapter 2, Question 17acidsFigure 2.19Sample Exercise 2.11Where did the elements come from?nucleosynthesisFigure 2.15fusion of hydrogenFigures 2.16 and 2.17Equations 2.2 and 2.3neutron captureandbdecayFigure 2.18Equation 2.4Sample Exercise 2.12ALTERNATIVE CONTEXTS(Key Terms Bolded)A Chemist’s View of a Soda Can RevisitedThe readily identifiable can of soda you may have used asan alternative context in Chapter 1 works equally well inChapter 2. The can is composed of aluminum, ametalorperhaps ametalloid. Carbon dioxide (CO2) is abinarymolecular compound(section 2.5) containingnonmetalsheld together bycovalent bonds. Carbon dioxide remainsa convenient starting point to introduce the law of defi-nite proportions, thelaw of multiple proportions(section2.5),chemicalformulas, and the nomenclature for binarymolecular compounds (section 2.6). The presence of 50 mgof sodiumcationsin many sodas introduces nomenclaturerules foralkali(and, by extension,alkaline earth)metals.Clearly ananionmust be present to balance the charge ofthe sodium ion. Twoacids—phosphoric acid (H3PO4) andcarbonic acid (H2CO3)—are present in sufficient concen-tration to justify their inclusion on the list of ingredients.Both acids containoxoanions, themselves examples ofpolyatomic ions(section 2.6). All of the elements found inmany sodas can be located on the periodic table.As an element, aluminum can serve as a model for study-ing atomic structure. Aluminum atoms have nuclei containingprotons(atomic number = 13) andneutrons, surrounded by13 electrons. The structure of aluminum atoms can be inferredfrom Rutherford’s experiments. While aluminum is 100%natural abundance of27Al (average mass= 26.98 amu), otherisotopesexist. For example,26Al has a half-life of about740,000 years and is seen in stars, wherenucleosynthesisoccurs. In the fall of 2007, it was reported that a new, veryheavy isotope of aluminum (42Al) had been detected.ACTIVE AND COLLABORATIVECLASSROOM EXERCISESClickers In ActionThe following clicker questions have been selected fromMargaret R. Asirvatham,Clickers in Action(W. W. Norton)andareavailableonwwnorton.com/instructors.Thequestions below were chosen to reflect the concepts intro-

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Atoms, Ions, and Compounds|9duced in the Sample Lecture Outline.The chapter andquestion numbers refer to PowerPoint slides fromClickersin Action.Clickers in Action,Chapter 2, Question 4The ion45Sc3+hasA)24 electrons, 21 protons, and 24 neutronsB)18 electrons, 21 protons, and 24 neutronsC)24 electrons, 24 protons, and 21 neutronsD)18 electrons, 24 protons, and 21 neutronsThis question asks students to identify thenumber ofprotons, neutrons, and electrons in an ion.This questionis more challenging than posing the same question for aneutral atom.Students will need to find Sc on the periodictable to determine the atomic number of Sc.You couldmodify the question by replacing, “45Sc3+” with “the 3+ion of scandium-45.”In the latter case, students are alsorequired to identify which element is scandium.Clickers in Action,Chapter 2, Question 13Classify each statement about the periodic table as true(T) or false (F). Then, select the answer with the threecorrect letters (for example, TTT).I) In the modern periodic table, elements are arranged inorder of increasing number of protons.II) Lead is a transition element.III) Radon is an inert gas.A)FTFC)FFTB)TFTD)TTFThis question requires students to use the periodic tableto identify the element symbols using the element name,to locate the element in the periodic table, and to assesswhether each statement is true or false.Clickers in Action, Chapter 2, Question 17Predict the correct name of the compound represented inthe box.NitrogenOxygenA)Nitrogen oxideC)Dinitrogen monoxideB)Oxygen nitrideD)Nitrogen dioxideThis question addresses the molecular scale views ofa chemical compound.Students must recognize thecomposition of the compound and then assign thecorrect name.Clickers in Action,Chapter 2, Question 21Which compound is represented by the correct formula?Assume the names are correct.A)Magnesium phosphide: Mg2P3B)Magnesium phosphate:Mg3(PO4)2C)Magnesium hydrogen phosphate: Mg(H2PO4)2D)Magnesium dihydrogen phosphate: MgHPO4This question tests the students’ knowledge of nomenclaturefor inorganic salts containing polyatomic anions.Studentsmay not have learned about “phosphide” but by analogy to“oxide,” they should be able to conclude that choice A isincorrect because the Mg ion carries a 2+ charge.ChemToursThe following ChemTours are available on theStudySpace(wwnorton.com/chemistry).Cathode Ray TubeSection 2.1, p. 44This ChemTour explores the effects of magnetic and electricfields and cathode rays.Millikan Oil Drop ExperimentSection 2.1, p. 45This ChemTour recreates the experimental procedure usedby Millikan to determine the charge of an electron.Rutherford ExperimentSection 2.1, p. 47This recreates Rutherford’s gold foil experiment, which ledto the discovery of the atomic nucleus.NaCl ReactionSection 2.5, p. 57This ChemTour illustrates the process by which a metal anda nonmetal combine to form a binary ionic compound, asseen in the reaction of sodium metal and chlorine gas.Synthesis of ElementsSection 2.7, p. 67This ChemTour animates the neutron capture process andexplains how elements are synthesized in stars.REFERENCESClassroom Demonstrations“AnEasyModelforTeachingMass/ChargeinMassSpectrometry,” R. V. F. Bravo and N. A. de Sousa,J.Chem. Educ., 1989, 66, 1039.“GeneralChemistryDemonstrationsBasedonNuclearand Radiochemical Phenomena,” R. H. Herber,J. Chem.Educ., 1969, 46, 665.

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