Atoms,MolecuLes, andlons

e.l > The €artg Historg of Chemistrg 2.2 > FundamentalChemical Laus 2.3 > Datton's Atomic Theorg 2.4 > €artu €rperiments to Chanacterize the Atom The €tectron Radioactivitg The NuctearAtom 2.S > The Modern Vieur of Atomic Structure: An Introduction e.6 > Moteculesand Ions 2.7 > An Introduction to the Periodic Tabte 2.8 > Naming Simpl.eCompounds BinargIonic ComPounds (TgpeI) Formutasfrom Names BinargIonic ComPounds (TgpeIi) Ionic Compoundsuith PotgatomicIons Binarg CovalentComPounds (TspeIII) Acids

Pol.arized light micrograph of crgstats of tartaric acid.

39 ) Improve gour probtemsotving skiil.s with ontine homeuork ) Get hetp ulhere gou needit urith tutoriats ) Readthe book ontine ulith an interactive e-Book,uhich incLudesnote taking and highLightingfearures ) See chemicalinteractions and demonstrations r.r-rithVisuatizations and Simulations )' I'uatch Go chemistrg mini video lectures ptagabteon ipods,iphones, and Mp3 pLagers ) Reinforce concepts from ctass ulith a video lesson from Thinkurel.l.

here doesone start in learning chemistry?clearly we must considersome es- sentialvocabulary and somethingabout the origins of thc sciencebefore we can proceed very far. Thus, while Chapter I provided background on the fundamental ideas and procedures of sciencein general,Chapter 2 coversthe specificchemical background nec- essary for understandingthe material in the next few chapters.The coverageof these top- ics is necessarilybrief at this point. We will developthese ideas more fully as it becomes appropriate to do so-A major goal of this chapteris to presentthe systemsfor naming chemical compoundsto provideyou with the vocabularynccessary to understandthis book and to pursueyour laboratorystudies. Becausechemistry is concernedfirst and foremost with chemical changes,we will proceed as quickly as possibleto a study of chemicalreactions (Chapters 3 and 4). How- ever, before we can discussreactions, we must considersome fundamentalideas about atoms and how they combine. IBLG:See questions from "Development ofAtomic Theory" 2.L > The €arl.g Historg of Chemistrg Chemistry has been important since ancient times. The processing of natural ores to produce metals for ornamentsand weaponsand the use of embalming fluids are just two applications of chemical phenomenathat were utilized prior to 1000 s.c. The Greeks were the first to try to explain why chemical changes occur. By about 400 n.c. they had proposedthat all matter was composedof four fundamental substances: fire, earth, water, and air. The Greeks also considered the question of whether matter is continuous, and thus infinitely divisible into smallerpieces, or composedof small, indi- visible particles. Supportersof the latter position were Demokritosx of Abdera (c. 460-<. 370 n.c.) and Leucippos, who used the term atomos (which later became atoms) to de- scribe these ultimate particles. However, becausethe Greeks had no experiments to test their ideas, no definitive conclusion could be reached about the divisibiliry of matter. ChemicalConnections: There's Goldin Them The next 2000 years of chemical history TherePlants were dominated by a pseudosciencecalled alchemy. Some alchemists were mystics and fakes who were obsessedwith the idea of turning cheap metals into gold. However, many alchemists were serious scientists, and this period saw important advances: The alchemists discovered several elements and learned to prepare the mineral acids. The foundations of modern chemistry were laid in the sixteenth century with the development of systematic metallurgy (extraction of metals from ores) by a German, Georg Bauer (1494-1555), and rhe medicinal application of minerals by a Swiss

*Democritus is an altematespelling.

a ,i 4 :.i ,:.i i€ 2.2 Fundamental Chemical Lauls 41

Figuree.r for Tn6Priesttey Medal is the highesthonor given by the AmericanChemical Society' lt is named sci- JosephPriestley, who was born in Englandon March13, 1733.He performedmany important could entificexperiments, among them the discoverythat a gas lateridentified as carbondioxide be dissolvedin waterto producese/tzer. Also, as a resultof meetingBeniamin Franklin in London in 1766,Priestley became interested in electricityand was the first to observethat graphitewas an efectricalconductor. However, his greatestdiscovery occurred in 1774when he isolatedoxygen by heatingmercuric oxide. Becauseof his nonconformistpolitical views, Priestley was forced to leaveEngland. He died in the UnitedStates in 1804.

alchemist/physicianknown as Paracelsus(full name: Philippus TheophrastusBombastus von Hohenheim[493-15al]). The first "chemist" to perform truly quantitative experiments was Robert Boyle (1627-l6gl),who carefully measuredthe relationshipbetween the pressureand volume of sci- air. When Boyle publishedhis book The SkepticalChymist in 1661,the quantitative quantitative encesof physics and chemistrywere born. In addition to his resultson the behavior of gur"r, Boyle's other major contributionto chemistry consistedof his ideas of el- about the chemicalelements. Boyle held no preconceivednotion about the number two ements.In his view, a substancewas an elementunless it could be broken down into gen- or more simplersubstances. As Boyle's experimentaldehnition of an clementbecame erally accepted,the list of known elementsbegan to grow, and the Greek systemof four elernentsfinally died.Although Boyle was an excellentscientist, he was not alwaysright- and For example,he clung to the alchemists'views that rnetals were not true elements that a way would eventuallybe found to changeone metal into another' eigh- The phenomenonof combustion evoked intense interest in the seventeenthand teenthcenturies. The Germanchemist Georg Stahl (166V1134) suggestedthat a substance ..phlogiston" sub- he called llowed out of the burning material, Stahl postulated that a con- stanceburning in a closed container eventually stoppedburning becausethe air in the tainer became saturatedwith phlogiston. Oxygen gas, discoveredby Joseph Priestley (1733-1804),*an Englishclergyman and scientist(Fig.2.l)' was found to supportvig- was orous combustionand was thus supposedto be low in phlogiston.In fact, oxygen originally called "dephlogisticatedair."

2.2 > FundamentalGhemical Laus eighteenthcentury, combustion had been studiedextensively; the gasescar- Experiment14: Composition 1:Percentage By the late discovered;and the list of elements Compositionand Empirical Formula of bon dioxide,nitrogen, hydrogen, and oxygenhad been Magnesium0xide continued to grow. However,it was Antoine Lavoisier (1143-1794), a French chemist (Fig.2.2), wno nnily explainedthe true natureof combustion,thus clearingthe way for the tremendousprogress that was made near the end of the eighteenth century' Lavoisier' like Boyle, regardedmeasurement as the essentialoperation of chemistry. His experiments, in which he carefully weighed the reactantsand products of various reactions, suggested that massis neither created ndr destroyed.Lavoisier's verification of this law of conser- century' vation of mass was the basis for the developmentsin chemistry in the nineteenth flfta!5r,i$:;fi€.i,txgfjff5'f ,lii;iltrreinic6"ili6-aiiion: that combustion involved oxygen (which oxYgene, iauoiii"r's quantitaiiv" experimentsshowed Oxygenis fromthe French by a process meaning"generator of acid," because it Lavoisier named), not phlogiston. He also discoveredthat life was supported Lavoisier wasinitially considered to be an integral that also involved oxygen und *ut similar in many ways to combustion-In 1789 in which Dartof allacids. published the first modern chemistry textbook, Elementary Treatiseon Chemistry, chemical knowledge assembled up to that time- Experiment Composition15:Percentage he presented a unified picture of the 15: Revolution broke out. Waterin a Hydrate Unfortunately, in the same year the text was published, the French

,1742-1786)' -O-yg." g- -as *-ally fustobserved by theSwedish chemist Karl W Scheele butbecause of oxygen' his ieiulS werepublished after Priestley's, the latter is commonlycredited with thediscovery Chapter Tuo Atoms,Motecutes, and Ions

Figure z.z Antoine Lavoisierwas born in paris on '1743. August 26, Although Lavoisierb father wanted his son to follow him into the legal profession,young Lavoisierwas fascinated by science. From the begin- ning of his scientific career,Lavoisier rec- ognized the importance of accurate mea- surements. His careful weighings showed that mass is conserved in chemical reac- tions and that combustion involves reac- tion with oxygen. Also, he wrote the first modern chemistry textbook. lt is not sur- prising that Lavoisieris often called the father of modern chemistry. To help support his scientific work, Lavoisierinvested in a privatetax- collectingfirm and marriedthe daughter of one of the company executives.His connection to the tax collectors proved fatal, for radicalFrench revolutionaries demandedhis execution,which occuned on the guillotineon May B, 1194.

Lavoisier, who had been associatedwith collecting taxes the government,was exe- cuted on the guillotine as an enemy of the people in 1j94. After 1800,chemistry was dominatedby scientistswho, following Lavoisier's lead, performed careful weighing experimentsto study the courseof chemicalreactions and to determinc the composition of various chemical compounds.One of these chemists,a Frenchman, JosephProust (1754_1826), showed thata given compoundalways contains exactly the sameproportion of elementsby mass. For example, Proust found that the sub- stance coppercarbonate is always5.3 partscopper to 4 partsoxygen to I part carbon (by mass).The principle of the constantcomposition of compounds,originally called ..proust's law," is now known as thg |a-_wof definite proportion.,;al:giventrclo+bound"A.ii,$ffid..g,,nf t._i#|!r,i,t:,,.^"..X.v;,!-r./;#lo,,is,#11..c,;p-I,o.p,._o"!-1j9fl.$,,919m9.$Is,:;pJit{nlssr. Proust'sdiscovery stimulated John Daiton gieO-tS++;, an Englishschoolteacher (Fig. 2.3),to thinkabout atoms as the particles that might compose elements. Dalton rea- soned that if elementswere composedof tiny individual particles,a given compound should alwayscontain the samecombination of theseatoms. This conceptexplained why the samerelative massesof elementswere always found in a given compound. But Figure 2.3 Dalton discovered another principle that convinced him even more of the exis- John Dalton(1766-1844), tence an Englishman, of atoms. He noted, for example, that carbon and oxygen form two different com- began teaching at a euaker school when '12. pounds that contain different relative amounts of carbon and he was His fascination oxygen, as shown by the with science following data: included an intense interest in meteorol_ ogy, which led to an interest in the oases of the air and their ultimate comporlnts, atoms. Dalton is best known for his atomic Mass of Orygen That Combines theory in which he postulated that the withlgofCarbon fundamentaldifferences among atoms are their masses. He was the first prepare to CompoundI 1.33g a table of relativeatomlc weights. Dalton was a humble man with sev_ CompoundII 2.66 e erat apparent handicaps: He was not ar_ ticulateand he was color-blind,a tenible problem for a chemist. Despite these dis- advantages, he helped Dalton noted to revolutionize that compound II contains twice as much oxygen per gram of carbon as the science of chemistrv. compound I, a fact that could easily be explained in terms of atoms. Compound I might 2.2 FundamentalChemicat Laws 43 be CO, and compound II might be CO2.* This principle, which was found to apply to compoundsof otherelements as well,bg99Pg,\-!,9y3"31$€11y'9j*t-S"9p--L:

To make sure the significanceof this observationis clear, in Example 2.1 considerdata for a seriesof compoundsconsisting of nitrogen and oxygen.

The followins data were collectedfor severalcompounds of nitrogen and oxygen:

Mass of Nitrogen That Gombines with'l g of Orygen

CompoundA l-750g CompoundIi 0.8750g CompoundC 0.4375g

Show how thesedata illustrate the law of multipleproportions'

Sotution For the law of multiple proportionsto hold, the ratios of the massesof nitrogencombin- ing with I gram of oxygen in each pair of compoundsshould be srnall whole numbers. We thereforecomputc the ratios as follows: A 1.150 2 B 0.8750 I B 0.8750 2 c 0.4315 I A 1.150 4 c-0.+:ls-r

Theseresults support the law of multiple proportions. ix.e.l$€ilF:Frs'i

The significanceof the data in Example 2.t is that compoundA containstwice as much nitrogen (N) per gram of oxygen (O) as does compound B and that compoundB containstwice as much nitrogen per gram of oxygen as does compoundC. These data can be explained readily if the substancesare composed of molecules made up of nitrogen atoms and oxygen atoms.For example,one set of possibilitiesfor compoundsA, B, and C is o,qfrl C:ffilL N_2 N_l N_l o-1 o-1

*Subscriptsare usedto show the numbersof atoms present.The number I is understood(not written). The symbols for the elementsand the writing of chemical formulas will be illustrated further in Sec- tions2.6 and2.7. Chapter Turo Atoms,Motecutes, and Ions

Now we can see that compound A contains two atoms of N for every atom of o, whereas compound B contains one atom of N per atom of O. That is, compound A contains twice as much nitrogen per given amount of oxygen as does compound B. Similarly, since com- pound B contains one N per O and compound C contains one N per rwo O's, the nitro- gen contentof compoundC per given amountof oxygen is half that of compoundB. Another set of compoundsthat fits the data in Example 2.1 is o,(il)

N_I N_i N=1 o-l o-2 o4

Verify for yourself that thesecompounds satisfy the requirements. Still anotherset that works is A: C: &€ e€ N 4 N2 N_2 o 2 6=t o- 4

See if you can come up with still another set of compoundsthat satisfiesthe data in Example2.1. How many more possibilitiesare there? In fact,an infinitenumber of otherpossibilities exists. Dalton could not deduceab- solute formulas from thc available data on relative masses.However, the data on the compositionof compoundsin terms of the relative massesof the elementssupported his hypothesisthat eachelement consisted of a certaintype of atom and that compoundswere formed from specificcombinations of atoms.

2.3 > Datton's Atomic Theorg ThinkwellVideo Lesson: Early In 1808 Dalton published A New Systemof Chemicttl Philosophy, in which he prcsented Discoveriesand the Atom his theory of atoms:

Thesestatements are a modern 1. Each elementis made up of tiny particlescalled atoms. paraphraseof Dalton's ideas. 2. The atoms of a given elementare identical;the atoms of differentelements are different in some fundamental way or ways. Chgr4icalcompounds ere formed when atoms of different elementq gorlbine always has the same relative numberb and 'r1:..,_..;.:;.. ; .'..1 :.r' - i:+';:;:i)

It is instructive to consider Dalton's reasoning on the relative massesof the atoms of the various elements.In Dalton's time water was known to be composed of the elements hydrogen and oxygen, with 8 grams of oxygen present for every I gram of hydrogen. If the formula for water were oH, an oxygen atom would have to have 8 times the mass of 2.3 Datton'sAtomic Theorg 45

\ :,a::. + +

2 volumes gaseouswater 2 volumes hydrogen combines with I volume oxYgen to form

+ + :.,..:,...:. l': 2.4 lure l epresentationof some of Gay-Lussac's lrg..':,.i.].'.:,' ..:l rerimentalresults on combining gas @ umes. I volume hydrogen combineswithlvolumechlorinetoform2volumeshydrogenchloride

of hydrogen a hydrogen atom. However, if the formula for water were HzO (two atoms 16 times as mas- for every oxygen atom), this would mean that eachatom of oxygcn is to that of tvvo sive as iach atomof hydrogen (since the ratio of the mass of one oxygen Dalton could hydrogensis 8 to 1). Becausethe formula for water was not then known, To solve the nlt sp"cify the relative massesof oxygen and hydrogenunambiguously' be as problem, Dalton made a fundamental assumption: He decided that nature would for water should simpteas possible.This assumptionled him to concludethat the formula be OH. He thus assignedhydrogen a massof 1 and oxygen a massof 8' Usingsimilarreasoningforothercompounds,Daltonpreparedthefirsttableof massis often de- atomic masses(sometimes called atomic weights by chemists,since Many of the termined by comparison to a standard mass-a process called weig,hlng). about masseswere later proved to be wrong becauseof Dalton's incorrect assumptions was an im- the formulas of certain compounds,but the constructionof a table of masses portant step forward. absolute Although not recognizedas such for many years,the keys to determining French chemist formulas fbr compounds were provided in the experimental work of the chemist named JosephGay-Lussac (1778-18j0) and by the hypothesisof an ltalian performedexperiments in which he )seph Louis GaY-Lussac,a French AmadeoAvogadro (1776-1856). In 1809Gay-Lussac volumesof gases nysicistand chemist,was remarkably measured(under the sameconditions of temperatureand pressure)thc pri- of hydrogen -'rsatile.Although he is now known that reactedwith eachother. For example,Gay-Lussac found that 2 volumes rarilyfor his studieson the combining that I volume of reactwith I volume of oxygen to form 2 volumesof gaseouswater and f volumesof gases,GaY-Lussac was I voi'me of chlorine to form 2 volumes of hydrogen chloride. These rstrumentalin the studiesof many of hydrogen reactswith le other properties of gases. Some of results are representedschematically in Fig. 2'4' temperature iay-Lussac'smotivation to learn about In l81l Avogadrointerpreted these results by proposinglhat at the same passion bal- of particles' Tltis ases arose from his for and pressure,equal volumesof dffirent gasescontain the same number roning.In fact, he made ascentsto the par- assumption(called Avogadro's hypothesis) makessense if the distancesbetween eights of over 4 miles to collect air u"ry gr"ut compared with the sizes of the particles. under these condi- amples, setting altitude records that ticles in a gas are of molecules present' not by the tood for about 50 years. Gay-Lussac tions, the volume of u gas is determined by the number rlso was the codiscoverer of boron and size of the individual Particles. he developer of a process for manufac- If Avogadro's hypothesis is correct, Gay-Lussac'sresult' uring sulfuric acid. As chief assayer of he French mint, Gay-Lussac developed 2volumesofhydrogenreactwithlvolumeofoxygen----)2volumesofwaterVapor nanytechniques for chemicalanalysis md invented many types of glassware can be expressedas follows: low used routinely in labs. Gay-Lussac ----' react with I molecule of oxygen t molecules of water ipent his last 20 years as a lawmaker in 2 moleculesx of hydrogen he Frenchgovernment. oxygen, and Theseobservations can best be explained by assumingthat gaseoushydrogen, and Cl2, respectively' ihereare seven elements that occur as chlorine are all composedof diatomic (two-atom) molecules:Hr, Or, liatomicmolecules: H2,N2, 02, Fr, clr, Brr,l, * A moleculeis a collection of atoms (seeSection 2'6)' Chapter Truo Atoms,Motecutes, and Ions

Berzelius, Selenium,and Silicon

Gay-Lussac'sresults can then be representedas shown in Fig. 2.5. (Note that this reason- ing suggeststhat the formula for water is HrO, not OH as Dalton believed.) Unfortunately,Avogadro's interpretations were not acceptedby most chemists,and a half-centuryof confusionfollowed, in which many clifferentassumptions were madeabout formulas and atomic masses. During the nineteenthcentury painstakingmeasurements were made of the masses of variouselements that combined to form compounds.From theseexperiments a list of relativeatomic massescould be determined.One of the chemistsinvolved in contributing to this list was a Swede named Jthorium and developedthe modern symbols for the elementsused in writing the formulas of compounds.

Figure 2.5 A representationof combining gases at the molecularlevel. The soheres representatoms in the molecules. 2.4 €artg €rperiments to Characterizethe Atom 47

seleniumin 1817 men to show that selenium seems to protect against The Atchemists' Sgmbols for in connectionwith prostate cancer. Seleniumis also found in the heart mus- Some Common €tements play role in proper heart func- and Compounds his studies of sul- cle and may an important furic acid. For tion. Becauseof these and other studies,selenium's rep- years selenium's utation has improved, and many scientists are now toxicity has been studying its functionin the human body. known, but only Siliconis the second most abundantelement in the earth's recently have we crust, exceededonly by oxygen.As we will see in Chapter 10; become aware compounds involvingsilicon bonded to oxygen make up most tha!,.it may have of the earth's sand, rock, and soil. Beaelius preparedsilicon pure (SiFo) ala:,ipositive-::on."human effect in its form in 1524 by heating silicon tetiafluoride health. with potassium metal Today,,5';11s.tforms the basis fpr the ,:,.:$.l ies have modern microelectronicsindustry centered near San Franbisco: in a place that has corne-to be known as l'Siiiqgn.Va{pyrilhe ' technology oi the silicon chip (see figure) with its printed circuitst'has.,trans-

2.4 > €arlg €xperiments to Characterize the AtOm IBLG:See questions from "The Nature of theAtom" ThinkwellVideo Lesson: UnderstandingElectrons On the basisof the work of Dalton, Gay-Lussac,Avogadro, and others,chemistry was be- ginning to make sense.The conceptof atoms was clearly a good idea. Inevitably,scien- tists beganto wonder about the nature of the atom. What is an atom made of, and how do the atoms of the various elements differ?

The €lectron The first important experimentsthat led to an understandingof the compositionof the atom were done by the English physicist J. J. Thomson (Fig. 2.6), who studiedelectrical dischargesin partially evacuatedtubes called cathode-ray tubes (Fig. 2.7) during the pe- riod from 1898 to 1903. Thomson found that when high voltage was applied to the tube, a"ray" he called a cathode ray (becauseit emanatedfrom the negativeelectrode, or cath- ode) was produced. Becausethis ray was produced at the negative electrode and was re- pelled by the negative pole of an applied electric field (see Fig. 2.8), Thomson postulated that the ray was a stream of negatively charged particles, now called electrons. From ex- periments in which he the deflection of the beam of electrons in a magnetic Figure 2.6 measured an electron: J. J. Thomson0856-1940) was an field, Thomson determined the charge-to-massratio of English physicist at Cambridge University.He received the Nobel " : -1.76 x 108C/g Prizein physicsin 1906. m Chapter Tr.rro Atoms, Motecutes,and Ions

Source of electrical potential

Stream of negative particles (electrons)

Partially cvacuated Metal glasstube electrode Figure 2.7 A cathode-raytube. The fast-moving electrons excite the gasin the tube,causing a glowbetween the electrodes.The green colorin the photois dueto the responseof the screen(coated with zinc sulfide) to the electronbeam.

whcre e representsthe chargeon the electron in coulombs (C) and /r?represents the electron massin grams. One of Thomson'sprimary goals in his cathode-raytube experimentswas to gain an Visualization:Cathode-Ray Tube understandingof the structureof the atom. He reasonedthat sinceelectrons could be pro- ducedfrom electrodesmade of varioustypes of metals,a// atoms must contain electrons. Since atoms were known to be electricallyneutral, Thomson further assumedthat atoms also must contain some positive charge.Thomson postulatedthat an atom consistedof a diffusecloud of positivecharge with the negativeelectrons embedded randomly in it. This model, shown in Fig. 2.9, is olten called the plum pudding model becausethe electrons are like raisinsdispersed in a pudding (the positivecharge cloud), as in plum pudding, a favorite English dessert. ln 1909 Robert Millikan (1868-1953), working at the University of Chicago, per- formed very clever experimentsinvolving chargedoil drops. Theseexperiments allowed him to determinethe magnitudeof the electroncharge (see Fig. 2.l0). With this value and the charge-to-massratio determinedby Thomson,Millikan was able to calculatethe mass Powerlecture:Cathode-Ray Tube of the electronas 9.11 x l0-3' kilosram.

Radioactivitg In the late nineteenthcentury scientistsdiscovered that certain elementsproduce high- energy radiation. For example, in 1896 the French scientistHenri Becquerelfound acciden- tally that a piece of a mineral containing uranium could produceits image on a photographic plate in the absenceof light. He attributed this phenomenonto a spontaneousemission of

Spherical cloud of positivecharge

electrode A classic English plum pudding in which the raisins Figure 2.8 Figure z.g representthe distribution of .t Deflectionof cathoderays by an appliedelectric field. Theplum pudding model of theatom. electrons in the atom. t: n :i ':; r,i ;'l :$ ii .5€ . Et igt 2.4 €arlg €rperiments to Characterizethe Atom 49

Atomrzer to produce oil Oil spray droplets --..--

Microscope

X rays produce chargeson the oil drops Electrically charged plates

(a) .b)

Figure z.ro (a)A schematic representationof the apparatus Millikanused to determinethe charge on the electron.The fall of charged oil droplets due to gravity can be halted by adjusting the voltage across the two plates. This voltage and the mass of the oil drop can then be used to calculatethe chargeon the oil drop. Millikan'sexperiments showed that the chargeon an oil drop is alwaysa whole-numbermultiple of the electroncharge. (b) RobertMillikan using his apparatus.

radiationby the uranium,which he calledradioactivity. Studiesin the early twentiethcen- tury demonstratedthree types of radioactiveemission: gamma (y) rays, beta (B) particles, and alpha (a) particles.A y ray is high-energy"light"; a B particle is a high-speedelectron; and an a particle has a 2* charge,that is, a charge twice that of the electron and with the opposite sign. The massof an a particle is 7300 times that of thc electron. More modes of radioactivity are now known, and we will discuss them in Chapter 19. Here we will con- sider only c particlesbecause they were used in some crucial early experiments.

Visualization:Millikan's 0il-Drop Experimenl

The Nuctear Atom Powerlecture:Millikan's 0il-Drop Experimenl In l9l1 Emest Rutherford (Fig. 2.11), who performed many of the pioneering experi- mentsto exploreradioactivity, carried out an experimentto testThomson's plum pudding model. The experiment involved directing c particles at a thin sheet of metal foil, as il- lustratedin Fig. 2.12. Rutherford reasonedthat if Thomson'smodel were accurate,the massivea particlesshould crash through the thin foil like cannonball.sthrough Eavze, as shown in Fig. 2.13(a).He expectedthe a particlesto travel through the foil with, at the most, very minor deflectionsin their paths.The resultsof the experimentwere very Figurez.u most of the a particles passed ErnestRutherford (1871-1937) was born different from those Rutherford anticipated. Although on a farm in New Zealand.ln 1895 he placedsecond in a scholarshipcompeti- Some cr particles Most particles tion to attend Cambridge University but are scattered pass straight was awarded the scholarship when the through foil winner decided to stay home and get manied.As a scientistin England, Sourceof Rutherford did much of the early work cr particles on characterizingradioactivity. He named the o and B particles and the y ray and coined the term halflife to describe an important attribute of radioactive ele- ments.His exoerimentson the behavior Screento detect Thin of o particlesstriking thin metal foils led metal foil him to postulatethe nuclear atom. He scatteredoparticles also inventedthe name p/'oton for the nu- cleus of the hydrogen atom. He received Figure z.rz the NobelPrize in chemistrvin 1908. Rutherford'sexperiment on @-particlebombardment of metalfoil. 50 Chapter Trlo Atoms,Motecutes, and Ions

Figure z.r3 (a) The expected results of the metal foil experimenti{ Thomson'smodel were correct.(b) Actual results. (a) (b)

ThinkwellVideo Lesson: Understanding straight through, many of the particles were deflected at large angles, as shown in the Nucleus Fig. 2.13(b),and somewere reflected, never hitting the detector.This outcomewas a great surpriseto Rutherford.(He wrote that this result was comparablewith shooting a how- ilzer at a piece of paperand having the shell reflectedback.) Rutherfordknew from theseresults that the plum pudding model for the atom could not be correct.The large deflectionsof the a particlescould be causedonly by a center of concentratedpositive chargc that containsmost of the atom's mass,as illustrated in Fig.2.l 3(b). Most of the a particlespass directly through the fbil becausethe atom is mostly open space.The deflecteda particlesare thosethat had a "close encounter"with the massivepositive centerof the atom, and the few reflecteda particlesare those that made a "direct hit" on the much more massivepositive center. In Rutherford'smind these resultscould be explainedonly in terms of a nuclear 3fe6-3n atom with a dcnsecenter of positive charge(the nucleus) with electronsmoving around the nucleusat a distancethat is larse relativeto the nuclearradius.

ThinkwellVideo Lesson: Modern Atomic Structure 2.5 > The Modern Vieu.rof Atomic Structure: Theforces that bind the positively An Introduction chargedprotons in thenucleus will be discussedin Chanter19. In the years since Thomson and Rutherford, a great deal has been learned about atomic structure.Bccause much of this materialwill be coveredin detail in later chapters,only ChemicalConnections: Seeing Atoms an introduction will be given here. The simplestview of the atom is that it consistsof 13 Visualization:Gold Foil Exoeriment a liny nucleus(with a diameterof about I0 cm) and electronsthat move about the 8 nucleusat an averagedistance of about l0 cm from it (seeFig. 2.14). As we will see later, the chemistry of an atom mainly results from its electrons. For Nucleus this reason,chemists can be satisfiedwith a relatively crude nuclearmodel. The nucleus is assumedto contain protons, which have a positive charge equal in magnitude to the electron's negative charge, and neutrons, which have virtually the same mass as a pro- ton but no charge.The massesand chargesof the electron, proton, and neutron are shown in Table2.1.

Powerlecture:Gold Foil Experiment

Particle Mass Gharge'

_to rcm.--"------_l Electron 9.109x l0-3tkg l- Proron 1.673x lo-27kg I + Neutron 1.675x 10-27ke None Figure z.r4 A nuclearatom viewed in crosssection. rThe magnitudeof the chargeof the electronand the proton is Notethat this drawing is not to scale. l.60 x t0-te c. 2.5 The ModernVieu of Atomic Structure: An Introduction 51

Figure z.r5 Two isotopesof sodium. Both have 11 protons and 1 l electrons,but they differ in the number of neutronsin their nuclei. ?1Nu ChemicalConnections: Playing Tag small size comparedwith the overall ChemicalConnections: lsotope Tales Two striking things about the nucleusare its size of the atom and its extremelyhigh density.The tiny nucleusaccounts for almost all ChemicalConnections: Reading the History the atom's mass.Its great density is dramaticallydemonstrated by the fact that a pieceof of Bogs nuclearmatcrial about the size of a pea would have a massof 250 million tons! Ihe chemistry0f an atom arisesfrom its An importantquestion to considerat this point is, "lf all atomsare composedof these electrons. same components,why do different atoms have different chemicalproperties?" The answer to this question lies in the number and the arrangementof the electrons-The electronscon- stitutc most of the atomic volumc and thus are thc parts that "intermingle" when atomscom- bine to form molecules.Therefore, the numberofelectrons possessedby a given atom greatly affects its ability to interact with other atoms. As a result, the atoms of different elements, which have different numbers of protons and electrons,show different chemical behavior. A sodium atom has I I protons in its nucleus.Since atoms have no net charge,the number of electronsmust equal the number of protons.Therefore, a sodium atom has I I electronsmoving around its nucleus.lt is always true that a sodium atom has 1l pro- tons and I I electrons.However, each sodium atom also has neutronsin its nucleus,and different types of sodium atomsexist that have differcnt numbersof neutrons.F-or exam- ple, considerthe sodium atoms representedin Fig.2.15. These two atoms are isotopes, or atoms with the same number of protons but dffirent numbersof neutrons.Note that the symbol for one particular type of sodium atom is written

Mass numbcr ?i*^ + Elcmcntsyrnbol lf the atomic nucleuswere the size of -) Atomic nunrbcr this ball bearing,a typical atom would be the size of this stadium where the atomic number Z (number of protons) is written as a subscript,and the mass written as a superscript.(The par- Massnumber - number A (the total number of protons and ncutrons)is protons, ) lx n- Elementsymbol ticular atom representedhere is called "sodium twenty-three."It has I 1 electlons,I I Atomicnumber/ and 12 neutrons.)Because the chemistry of an atom is due to its electlons,isotop€s show al- most elementscontain nlixtures of isotopes. ChemicalConnections: Elemental Analysis most identical chemical properties.[n nature CatchesElephant Poachers

2.2

Write the symbol for the atom that has an atomic number of 9 and a mass number of 19. How many electrons and how many'neutrons does this atom have?

Sotution The atomic number 9 means the atom has 9 protons. This elementis calledfluorine, sym- bolized by F. The atom is representedas '3p Chapter Tuo Atoms,Motecutes, and Ions

and is called nineteen. f.uorine since the atom has 9 protons, it also must have 9 elec_ trons to achieve electrical neutraliry. The mass numbeigives the total number of protons and neutrons, which means that this atom has l0 neutrons.

2.6 > Molecutesand fons ThinkwellVideo Lesson: Describing From a chemist'sviewpoint, the ChemicalFormulas most interestingcharacteristic of an atom is its ability to combine with other atoms to form compounds.It was John Darton who first recog_ nized that chemical compounds are collections of atoms, but he could not determine the structure of atom.sor their means for binding to each other. During the twentieth century we learned that atoms have electrons and that these electrons participate in bonding one atom to another.we will discuss bonding thoroughly g Powerlecture:Covalent in chapters and Bonding 9; here, we will introducesome simple bonding ideasthat will be useful in the next rew cnaDters. The forces that hold atoms togetherin compoundsare called chemical bonds. One way that atoms can form bonds isby sharing electrons.These bonds are called cova- lent bonds, and the resulting collectionof aioms is callecla molecule.Molecules can be representedin several different ways. The simplest method is the chemical formula, Visualization:Covalent Bonding in which the symbols for the elementsare usedio indicate the types of atoms present and subscriptsare usedto indicate the relative numbersof uto-r. For example,the for- mula for carbondioxide is cor, meaningthat each moleculecontains I atom of car- bon and 2 atomsof oxygen. Examplesof morecules that contain covalentbonds are hydrogen(Hr), water (Hzo), oxygen (Ot), ammonia(NH,), and methane(CHo). More informatiin abouta moleculeis given by its structural formula, in which the individual bonds are shown (indicatedby lines)' Structuralformulas may or may not indicatethe actualshape of the molecule.For example,water might be representedas

The structureon the right shows the actualshape of the water molecule.Scientists know from experimentalevidence that the moleculelooks like this. (we will study the shapes of molecules further in Chapter g.) The structural formula for N ammonia is shown in the margin at left. Note that atoms connectedto the central atom by dashedlines are behind the pl-aneof the paper, and atoms connectedto the central atom by wedges are in front of the plane of the paper. In a compoundcomposed "',1"" of molecules,the individual moleculesmove around as Ammonia independent units. For example, a molecule of methane gas can be representedin sev_ eral ways. The structural formula for methane(CHo) is slo=wnin Fig. 2. l6(a). The space- filling model of methane, which shows the relative sizes of the atoms as well as their relative orientation in the molecule, is given in Fig. .2.r6(b). Bail-and-stick moders are also used to represent molecules. The ball-and-stick strucfure of methane is shown in Fig.2.l6(c). A second type of chemical bond results from attractions among ions. An ion is an atom or group of atoms that has a net positive or negative charge. Tie best-known ionic compound is common table salt, or sodium chloride, which forts when neutral chlorine and sodium react. 2.6 Motecutesand Ions 53

C \.. Figure e.rG ,,,- l .'.. (a)The structuralformula for methane. 1 (b) Space-fillingmodel of methane' This H'l'H type of model shows both the relative H sizes of the atoms in the molecule and IVlethane their spatial relationships.(c) Ball-and- stick model of methane. (aJ

To see how the ions are formed, considerwhat happenswhen an electronis trans- ferred from a sodium atom to a chlorine atom (the neutronsin the nuclei will be ignored):

Visualization:Determining Formulas for Neutralsodiurr lonicCompounds atorn(Na)

Sodium ion (Na+)

Powerlecture:Determining Formulas for lonicCompounds

- Minus I electron.+

I I electrons Na* is usuallycalled the sodiumion ratherthan the sodium cation. Also Cl is calledthe chlorideion ralherthan the With gne electronstripped off, the sodium,with its l1 protonsand only l0 electrons,now chlorideanion. In general, when a spe- pctsitiveion. A positiveion is called a cation. The cificion is referredto, the wordlon has a net 1* charge-it has becomea ratherthan cation or anronis used. so{ium ion is written as Na*, and the processcan be representedin shorthandform as Na --+ Na' + e

If an electronis addedto chlorine,

Chloride ion (cl-)

Neutral chlorine atom (Cl)

-Plus I electron-

17 electrons

l8 electrons Chapter Truo Atoms,Molecutes, and Ions

Figure e.r7 Sodiummetal (which is so softit can be cut witha knifeand which consists of individualsodium atoms) reacts with chlorine gas (whichcontains Cl, molecules)to formsolid sodium chloride (which contains Na* andCl ionspacked together).

the 18 electronsproduce a net l- charge;the chlorinehas becomean ion with a negative charge-an anion. The chloride ion is written as Cl , and the process is representedas Cl + e- ---+ Cl Because anions And cations have opposite charges,they attract each other. This force of attraction between oppositely charged ions is called ionic bonding. As illustrated in Fig. 2.17, sodium metal and chlorine gas (a green gas composedof cl, molecules)react to form solid sodium chloride, which containsmany Na+ and Cl ions packedtogether and forms the beautiful colorlesscubic crystalsshown inFig.2.l7. A solid consistingofoppositely chargedions is called an ionic solid. Ionic solids can consistof simple ions, as in sodium chloride,or of polyatomic (many atom) ions, as in ammonium nitrate (NH4No3), which contains ammonium ions (NHo+) and nitrate ions (NO:-).The ball-and-stickmodels of theseions are shown in Fis. 2.1g. 2.7 > An Introduction to the Periodic Table In a room where chemistry is taught Figurez.r8 or practiced, a chart called the periodic table is al- most certain to be found hanging Ball-and-stickmodels of the ammonium on the wall. This chart shows all the known elements ion (NHo*)and the nitrate ion (NO3-). and gives a good deal of information about each. As our study of chemistry progresses, These ions are held together by the usefulnessof the periodic table will become more obvious. This section will simolv covalent bonds. introduce it to vou. 2.T An Introduction to the PeriodicTabl.e 55

Noble gases i Halogens l8 8A

IJ l4 l5 16 tl 'IA 3A 5A 61\

o

*Lanthanides

tActinides

Figure z.rg Theoeriodic table.

ChemicafConnections: Trace Elements: Small A simplified version of the periodic table is shown in Fig. 2.19. T\e letters in the butCrucial boxes are the symbols for the elements; these abbreviations are based on the current element names or the original names (see Table 2.2). The number shown above each

Powerlecture:Comparison of a Molecular Compoundand an lonic Compound

Visualization:Comparison 0f a M0lecular Current Name Original Name Symbol Compoundand an lonic Compound Antimony Stibium Sb Copper Cuprum Cu ThinkwellVideo Lessons: Femrm Fe Creatingthe Periodic Table Iron NamingChemical Compounds Lead Plumbum Pb Mercury Hydrargyrum Hg Potassium Kalium K Silver Argentum Ag Sodium Natrium Na Tin Stannum Sn Tungsten Wolfram W t*, Chapter Turo Atoms,Motecutes, and Ions

Hassium Fits Right In

element 108. does not exist in must be made in a particleaccel- rd in 1984 and can be made by ::e.T.'11 1.:rti:'j.

Experiment25: Properties of Representative symbol ts rheatomic numher (number of protons)for that element.For example,carbon (C) Elements has atomic number 6, and lead (Pb) has atomic number 82. Most of the elementsare metals. Metals havecharacteristic physical properties such as efficientconduction of heat and electricity,malleability (they can be hammeredinto thin sheets),ductility (they can be pulied into wires), and (often) a lustrousappearance. Chemically, metals tend to lose electronsto form positive ions. For example,copper is a typical metal. It is lustrous(al- though it tarnishesreadily); it is an excellentconductor of electricity (it is widely usedin electricalwires); and it is readily formed into variousshapes, such as pipesfor water sys- tems. Copper is also found in many salts, such as the beautiful blue copper sulfate, in which copper is presentas Cu2* ions. Copper is a member of the transitionmetals-the metalsshown in the centerof the periodic table. Metalstend to formpositive ions; The relativcly few nonmetals appearin the upper-right corner of the table (to the right nonmetalstend to formneoative ions of the heavy line in Fig. 2.19), excepthydrogen, a nonmetal that residesin the upper-left corner.The nonmetalslack the physical propertiesthat characterizethe metals.Chemically, they tend to gain electrons in reactions with metals to form negative ions. Nonmetals of- ten bond to each other by forming covalent bonds. For example, chlorine is a typical non- metal. Under normal conditionsit exists as Cl, molecules;it reactswith metals to form saltscontaining Cl- ions (NaCl, for example);and it forms covalentbonds with nonmetals Elementsinthe same vertical column in (for example,hydrogen chloride gas, HCI). theperiodic table form a group(or family) The periodic table is arranged so that elements in the same vertical columns (called andgenerally have similar properties. groups or families) have similar chemical properties. For example, all of the alkali met- als, membersof Group lA-lithium (Li), sodium(Na), potassium(K), rubidium (Rb), ce- sium (Cs), and francium (FrFare very active elementsthat readily form ions with a 1+ charge when they react with nonmetals.The membersof Group 2A-beryllium (Be), mag- nesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra)-are called the alkaline earth metals. They all form ions with a 2* charge when they react with non- metals. The halogens, the members of Group 7A-fluorine (F), chlorine (Cl), bromine Q*. (Br), iodine (I), and astatine(AtFall form diatomic molecules.Fluorine, chlorine, bromine, and iodine all react with metals to form salts containing ions with a 1- charge (F-, Cl-, Br-, and I-). The members of Group SA-helium (He), neon (Ne), argon (Ar), krypton Samplesof chlorinegas, liquid bromine, (Kr), xenon (Xe), and radon (RnFare known as the nolrle gases.They all exist under nor- and solid iodine. mal conditions as monatomic (single-atom) gasesand have little chemical reactivity. 2.8 NamingSimpte Compounds 57

Note from Fig.2.19 that alternate sets of symbols are used to denote the groups. The symbols lA through 8A are the traditional designations, whereas the numbers I to 18 havebeen suggestedrecently. In this text the 1A to 8A designationswill be used. The horizontal rows of elements in the periodic table are called periods. Horizontal row 1 is called thefrst period (it containsH and He); row 2 is called the secondpeiod (elementsLi through Ne); and so on. We will learn much more about the periodic table as we continue with our study of Anotherformat of the oeriodic table will chemistry.Meanwhile, when an elementis introducedin this text, you shouldalways note bediscussed inSection 7.'11. its position on the periodic table.

IBLG:See questions from "Nomenclature" and"Naming Compounds" 2.8 > Naming SimpLeCompounds When chemistrywas an infant science,there was no systemfor namingcompounds. Names suchas sugarof lead,blue vitrol, quicklime, Epsom salts,milk of magnesia,gypsum, and laughing gas were coined by early chemists.Such namesare called commonnames. As chemistrygrew, it becameclear that using common namesfor compoundswould lead to unacceptablechaos. Nearly 5 million chemicalcompounds are currently known. Memo- ChemicalConnections: How Can Water Be rizing common namesfor thesecompounds would be an impossibletask. Hardor Soft? The solution, of course,is to adopt a systemfor naming compoundsin which the nametells somethingabout the compositionof the compound.After learningthe system, a chemistgiven a formula shouldbe able to namethe compoundor, given a name,should be able to constructthe compound'sformula. In this sectionwe will specify the most im- portantrules for namingcompounds other than organiccompounds (those based on chains of carbon atoms). We will beginwith the systemsfor naminginorganic binary compounds compounds ThinkwellVideo Lesson: Namino Chemical composedof two slsrnsnts-vr'hich we classify into varioustypes for easierrecognition. Compounds We will considerboth ionic and covalentcompounds.

Binarg Ionic Compounds(Tgpe I) Binary ionic compounds contain a positive ion (cation) always written first in the for- mula and a negativeion (anion). In naming thesecompounds, the following rules apply:

1. The cation is always named first and the anion second. A monatomiccation has the same name 2. A monatomic(meaning(meanino "one-atom")"one-atom') cation takes its namenar from the name of asits oarent element.

Some common monatomic cations and anions and their names are given in Table 2.3. The rules for naming binary ionic compounds are illustrated by the following examples: Informulas ofionic compounds, simple Compound lons Present Name lonsare represented bythe element sYmbol:Clmeans Cl-, Na means Na+, NaCl Na*, Cl- Sodium chloride andso on. KI K*, I_ Potassiumiodide CaS Ca2*,s2- Calcium sulfide Li3N Li+, N3- Lithium nitride CsBr Csn,Br- Cesium bromide Mgo Mgt*, ot- Magnesium oxide 58 Chapter Tulo Atoms,Motecutes, and Ions

Cation Name Anion Name

H* Hydrogen H- Hydride Li* Lithium F- Fluoride Na* Sodium Cl- Chloride K* Potassium Br- Bromide Cst Cesium I- Iodide Be2* Beryllium 02- Oxide Mgt* Magnesium 52- Sulfide Ca2r Calcium N3 Nitride Ba2* Barium P3 Phosohide Al31 Aluminum

2.3

Name each binary compound. a. CsF b. AlCl3 c. LiH Sotution a. CsF is cesium fluoride. b. Alclr is aluminumchloride. c. LiH is lithium hydride.

Notice that, in eachcase, the cation is namedfirst, and then the anion is named. '".iii,'t,,,i.,,;,,:i.,ffi,{lft.1,1n l

Formutas from Names So far we have startedwith the chemical formula of a compoundand decidedon its sys- tematic name.The reverseprocess is also important. For example,given the name cal- cium chloride, we can write the formula as CaCl, becausewe know that calcium forms only Ca2* ions and that, sincechloride is Cl , two of theseanions will bc requiredto give Ion Systematic Name a neutral compound. Fe3* Iron(lll) Fe2* Iron(II) Binarg lonic Compounds(Tgpe II) Cu2* Copper(Il) Cu* Copper(I) In the binary ionic compoundsconsidered earlier (Type I), the metal presentforms only co3n Cobalt(III) a single type of cation. That is, sodium forms only Na+, calcium forms only Caz*, and Co2* Cobalt(Il) so on. However, as we will see in more detail later in the text, there are many metals that sna* Tin(IV) form more than one type of positive ion and thus form more than one type of ionic com- Sn2* Tin(II) pound with a given anion. For example,the compoundFeCl2 contains F'e2+ ions, and the Pb4* Lead(lV) compoundFeCl, containsFe3* ions. In a casesuch as this, the chargeon the metal ion Pb2* Lead(II) must be specified.The systematic names for these two iron compounds are iron(Il) chlo- Hg'* Mercury(Il) ride and iron(III) chloride, respectively, where the Roman numeral indicates the charge Hgz2*' MercuryQ) Ag* Silvert of the cation. Zn2n Zinct Another system for naming these ionic compounds that is seen in the older literature Cd2+ Cadmiumt was used for metals that form only two ions. The ion with the higher charge has a name ending in -ic, and the one with the lower charge has a name ending in -ous. In this sys- *Note that mercury(I) ions always occur tem, for example, Fe3* is called the ferric ion, and Fe2* is called the ferrous ion. The bound togetherto form Hgr2+ ions. TAlthoughthese are transition metals,they names for FeCl, and FeClr are then ferric chloride and ferrous chloride, respectively. In form only one tipe of ion, and a Roman this text we will use the system that employs Roman numerals. Table2.4lists the system- numeral is not used. atic names for many common type II cations. 2.8 NamingSimpLe Compounds 59

2.4

Given the following systematic names, write the formula for each compound: a. potassiumiodide tr. calcium oxide c. gallium bromide

Sottrtion Name Formula Comments

a. potassiumiodide KI ContainsK+ andI-. b. calcium oxide CaO ContainsCa2t and O2-. c. gallium bromide GaBr., ContainsGar* and Br-, Must havc3Br- to balancecharge of Ga'-.

2.5

1. Give the systematicname for eachof the following compounds: a. CuCl b. HgO c. FerOi

2. Given the following systcmaticnames, write the formula for eachcompound: a. Manganese(IV)oxide b. I-ead(II) chloride Typell binaryionic compounds contain a Sotution morethan one type metalthat can form type of cation.Thus ofcation. All of thesecompounds include a metal that can form more than one we must first determinethe chargeon eachcation. This can be done by recognizingthat A compoundmust be electrically neutral. a compound must be electrically neutral; that is, the positive and negativecharges must exactly balance. l.

Formula Name Comments

a. CuCI Copper(I)chloride Becausethe anionis C]-, the cationmust be Cu+ (for chargebalance), which requiresa Roman nu- meral I. b. HgO Mercury(II) oxide Becausethe anion is 02 , the cationmust be Hg2+ lmercury(II)1. c. Fe2O, Iron(III) oxide The three 02- ions carry a total chargeof 6-, so two Fe3* ions [iron(III)] are neededto give a 6* charge. ,,

Name Formula Comments a. Manganese(IV)oxide MnO2 Two 02- ions (totalcharge 4-) aterequired by the Mna+ ion [manganese(IV)]. b. Lead(II) chloride PbCl2 Two Cl- ions are required by the Pb2* ion [ead(Il)] for charge balance. GhapterTuro Atoms, Motecutes,and Ions

Figure z.zo Flowchartfor naming binary ionic compouncls.

A compoundcontaining a transition metal Note that the use of a Roman numeralin a systematicname is requiredonly in cases usuallyrequires a Roman numeral in its where more than one ionic compoundforms betweena given pair of elements.This case name. most commonly occurs for compoundscontaining transition metals, which often form morerhan one carion. ple,pd_$,{$glr,ptifgd#y-oBg.ip,4$$.9,9;notjni"e,d-;rtg-..:'b ,f4i a&mail:numeial,:Common metals that do not require Roman numerals are the Group which only l* ions; the Group 2A elements,which form only 2* lA elements, form .,r ions; and aluminum, which forms only Alr*. The elementsilver deservesspecial mention I silver is found as the Ag+ ion. Therefore,al- $\ at this point. In virtually all its compounds ; though silver is a transitionmetal (and can potentially form ions other than Ag+), silver { compoundsare usually named without a Roman numeral.Thus AgCl is typically called , silver chloride rather than silver(I) chloride, although the latter name is technicallycor- rect. Also, a Roman numeral is not used for zinc compounds,since zinc forms only the Zn2* ion. As shown in Example 2.5, whcn a metal ion is presentthat forms more than one type of cation, the chargeon the metal ion must be determinedby balancingthe positive and negativecharges of the compound.To do this you must be able to recognizethe common cations and anions and know their charges(see Tables 2.3 and 2.5). The procedurefor naming binary ionic compoundsis summarizedin Fig. 2.20.

1. Give the systematicname for eachof the following compounds:

a. CoBrt b. CaCl2 c. Al2O3 2. Given the following systematicnames, write the formula for each compound:

a. Chromium(Ill) chloride b. Gallium iodide

Solution l.

Formula Name Comments

a. CoBr2 Cobalt(Il) bromide Cobalt is a transition metal; the compound name Variouschromium compounds dissolved in water. From left to right: CrClr, must have a Roman numeral. The two Br- ions K2Cr"O7,Cr(NO")r, CrCl3, K2CrO4. must be balancedby a Co2nion. 2.8 NamingSimpLe Compounds 61

Formula Name Comments

b. CaCl, Calcium chloride Calcium, an alkaline earth metal, forms only the Ca2+ion. A Roman numeralis not necessary. c. AlrO. Aluminum oxide Aluminum forms only the Al3+ ion. A Roman numeral is not necessary. 2.

Name Formula Comments

Chromium(III) chloride crCl3 Chromium(Ill) indicatesthat Ct'+ is present, so 3 Cl ions are neededfor chargebalance. b. Galliumiodidc GaI, Gallium alwaysforms 3* ions, so 3 I- ions are required for chargc balance.

,1 . : .'.-l .. .' -. .;jr,l,:tii&ffi

The commonType I and Type II ions are summarizedin Fig.2.2l. Also shownin Fip.2.21 a.rc the common monatomic ions.

Ionic Compoundsu.rith Potgatomic Ions We havenot yet consideredionic compoundsthat contain polyatomic ions. For example, the compoundammonium nitrate, NH4NO3, contains the polyatomicions NHa+ andNO3-. Polyatomicion formulas must be Polyatomicions are assignedspecial names that must be memorizedto name the com- memorized. poundscontaining them. The most important polyatomic ions and their namesare listed in Table2.5. ChemicalConnections: Talking Tadpoles Note in Table 2.5 that severalseries of anions contain an atom of a given element and different numbersof oxygen atoms.These anions are callcd oxyanions. When there are two members in such a series, the name of the one with the smaller number of oxy- gen atoms ends in -ite and the name of the one with the larger number ends in -ate-for example,sulfite (SO.2-) and sulfate(SOot-).When more than two oxyanionsmake up a series,lrypo- (less than) and per- (more than) are used as prefixes to name the members of the serieswith the fewest and the most oxygen atoms,respectively. The best example involvesthe oxyanionscontaining chlorine, as shown in Table 2.5.

Figure z.zr ao -on TypeI cations aorn*onType II cations ao-.on monatomicanions Thecommon cations and anions. ffi ffi ffi Motecutes,and Ions

Name lon Name

Hg22* Mercury(I) NCS- or SCN- Thiocyanate NHo* Ammonium Cort- Carbonate NO, Nitrite HCO3- Hydrogen carbonate No:- Nitrate (bicarbonate is a widely Sor'- Sulfite used common name) SO.t- Sulfate CIO or OCI Hypochlorite HS04 Hydrogen sulfate clo2 Chlorite (bisulfateis a widely clo3- Chlorate used common name) cl04- Perchlorate oH- Hydroxide c2H3o2 Acetate cN- Cyanide MnOa Permanganate POo' Phosphate Cr20r2- Dichromate HPO42- Hydrogen phosphate C.Oo'- Chromate H2PO4 Dihydrogenphosphate or.'- Peroxide Croo' Oxalate SrO,t Thiosulfate

E 2.7

l. Give the systematicname for eachof the following compounds: a. NarS0, b. KH2PO4 c. Fe(NO,)3 d. Mn(OH), e. Na2SO, f. Na2COj

2- Given the following systematicnames, write the formula for eachcompound: a. Sodium hydrogencarbonate b. Cesium perchlorate c. Sodium hypochlorite d. Sodiumselenate e. Potassiumbromate

Sotution l.

Formula Name Comments a. NarSOo Sodium sulfate b. KHzPO4 Potassiumdihydrogen phosphate c. Fe(NO.). Iron(I[) nitrate Transition metal-name must contain a Roman numeral. The Fe3+ ion bal- ancesth-ree NOr- ions. d. Mn(OH)2 Manganese(Il) hydroxide Transition metal-name must contain a Roman numeral. The Mn2+ ion bal- ancesthree OH- ions. e. NarSO3 Sodium sulfite f. NarCO3 Sodium carbonate 2.8 Naming SimpLeCompounds ffi

i; ) * :.. Name Formula Comments

a. Sodiumhydrogen NaHCO3 Often called sodium bicarbonate carbonate b. Cesiumperchlorate CsClOo c. Sodiumhypochlorite NaOCI d. Sodiumselenate Na2SeOa Atoms in the same group, like sulfur and selenium,often form similar ions that are namedsimilarly. Thus SeOa2- is selenate, likc SOo2(sulfate). e. Potassiumbromatc KBrO3 As above, BrOj is bromate, like ClO3- (chlorate).

Binarg Covalent Compounds(Tgpe III) ln binarycovalent compounds, Ine Binary covalent compounds are formed between two nonmetais.Although thesecom- elementnames follow the same rules as pounds do not contain ions, they are named very similarly to binary ionic compounds. forbinary ionic compounds.

1. The first element in the formula is named first, using the full elementname. 2. The second element is named as if it were an anion. 3. Prefixes are used to denote the numbers ol atgmsOregqn!, Thege qr.,eJllqi g.r9 ,t .1...,i....:.t_,. .r. - '..i ,,-,.:!'i,.r. bn in'Tabte'2.0.

To see how theserules apply, we will now considerthe namesof the severalcova- lent compoundsformed by nitrogenand oxygen: Gompound Systematic Name Common Name

NrO Dinitrogenmonoxide Nitrous oxide NO Nitrogen monoxide Nitric oxide Prefix Number Indicated Noz Nitrogen dioxide N,O: Dinitrogen trioxide mano- I Nzo+ Dinitrogen tetroxide di- 2 Nrot Dinitrogen pentoxide tri- 3 tetra- 4 Notice from the preceding examplesthat to avoid awkward pronunciations, we often penta- 5 drop the final o or a of the prefix when the element begins with a vowel. For example, hexa- 6 NrOo is called dinitrogen tetroxide, not dinitrogen tetraoxide, and CO is called carbon hepta- 7 monoxide, not carbon monooxide. octa- g Some compounds are always referred to by their coflunon names.Three examplesare nona- 9 water, ammonia, and hydrogen peroxide. The systematic names for H2O, NH3, and H2O2 deca- lo are never used. Chapter Tuo Atoms, Motecutes,and Ions

2.8

1. Name each of the following compounds:

a. PClr b. PCl3 c. SO,

2. From the following systematicnames, write the formula for each compound: a. Sulfur hexafluoride b. Sulfur trioxide c. Carbon dioxide

Sotution l.

Formula Name

a. PCl, Phosphoruspentachloride b. PCll Phosphorustrichloride c. SO2 Sulfur dioxide 2.

Name Formula a. Sulfur hexafluoride SFo b. Sulfur trioxide SO, c. Carbon dioxide CO, Ili":ii&+1+il,{-S"i-S.

The rules for naming binary compounds are summarized in Fig. 2.22. Prefixes to in- dicate the number of atoms are used only in Type III binary compounds (those contain- ing two nonmetals).An overall strategyfor naming compoundsis given inFig.2.23.

|:i

Figure z.zz A flowchartfor namingbinary compounds. NamingSimpte Compounds

Figure z.z3 Overallstrategy for namingchemical compounds.

2.9

l. Give the systematicname for eachof the following compounds: a. PoO,s b. Nb2o5 c- Li.rO, d. Ti(No3)4

2. Given the following systematicnames, write the formula for eachcompound: a. Vanadium(V)fluoridc b. Dioxygen difluoride c. Rubidiumperoxide d. Gallium oxide

Solution l.

Compound Name Comment

a. PoO,6 Tetraphosphorus Binary covalentcompound (Type III), decaoxide so prefixesare used.The a in deca- is sometimesdropped. b. Nb2o5 Niobium(V) oxide Type II binary compound containing Nb5+and 02- ions. Niobium is a tran- sition metal and requires a Roman numeral. c. LirO2 Lithium peroxide Typ" I trinary compound containing the Li+ and Or2- (peroxide) ions. d. Ti(No3)4 Titanium(IV) nitrate Not a binary compound. Contains the Tia+ and NO3- ions. Titanium is a transition metal and requires a Roman numeral. Chapter Truo Atoms, Molecules,and Ions

t

Name ChemicalFormula Comment

a. Vanadium(V) fluoride Ws The compoundcontains V5* ions and requiresfive F- ions for charge balance. b. Dioxygen difluoride orFz The prefix di- indicatestwo of each atom. c. Rubidium peroxide Rb2o2 Becauserubidium is in Group 1A, it forms only 1* ions. Thus two Rb* ions areneeded to balancethe 2- charge on the peroxide ion (ort-). d. Gallium oxide Becausegallium is in Group 3,A, like aluminum, it forms only 3* ions. Two Ga3* ions are required to balance the charge on three 02 ions.

Lruilli..tE.iii$-

Acids

Acidscan be recognizqdby the hydrogen When dissolvedin water, certain moleculesproduce a solution containingfree H1 ions thatappears first in the formula. (protons).These substances, acids, will be discussedin detail in Chapters4, 14, and 15. Here we will simply presentthe rules for naming acids- An acid is a moleculein which one or more H* ions are attachedto an anion.The rules for naming acidsdepend on whcther the anion containsoxygen. If the name of the anion ends in -ide, the acid is named with thc prefrx hydro- and the suffix -ic. For example, when gaseousHCI is dissolved in water, it forms hydrochloric acid. Simi- Iarly, HCN and H2S dissolved in water are called hydrocyanic and hydrosulfuric acids, respectively. HF Hydrofluoric acid When the anion contains oryBen, the acidic name is formed from the root name of HCI Hydrochloric acid the anion with a suffix of -ic or -oas, dependingon the name of the anion. HBr Hydrobromic acid -ate, -lc HI Hydroiodic acid l. If the anion name ends in the suffix is added to the root name. For example, HCN Hydrocyanic acid H2SO4contains the sulfateanion (SOr2-) and is called sulfuric acid; H3PO4contains HzS Hydrosulfuric acid the phosphateanion (POo'-) and is called phosphoricacid; and HC'H3O2contains the acetateion (CrH3O2-) and is called acetic acid. *Note that theseacids are aqueous solutionscontaining these substances. 2. If the anionhas an -ite ending, the -ite is replacedby -ous.For example,H2SO3, which containssulfite (SOr2-), is named sulfurousacid; and HNO2, which containsnitrite (NOz-), is namednitrous acid.

The application of these rules can be seen in the names of the acids of the oxyanions of chlorine:

Acid Anion Name

HNO3 Nitric acid HCI04 Perchlorale Perchloric acid HNO2 Nitrous acid HCIO3 Chlorate Chloric acid HrSOo Sulfuric acid HCIO2 Chlorire Chloroas acid H2SO3 Sulfurousacid HCIO Hypochlorire Hypochloror.rsacid H3PO4 Phosphoric acid The names of the given HC2H3O2 Acetic acid most important acids are in Tables 2.7 and 2.8. An overall strat- egy for naming acids is shown inFig.2.24. i, i'i llii For Revieu 67

Figure z.z4 A flowchartfor namingacids. An acid is best consideredas one or more H* ions attachedto an anion.

t KeUTerms I -,r:. Section z.z law of conservationof mass law of definite proportion law of multiple proportions Section 2.3 atomic masses atomic weights Avogadro'shypothcsis Section 2.4 cathode,ray tubes electrons radioactivity nuclear atom I

nucleus I

Section 2.5 I proton neu$on isotopes atomic number massnumber Section 2.6 chemical bond covalent bond numter,but different mass numbers. molecule by sharing electronsto form clvalent chemical formula shuctural formula space-filling model i: ball-and-stick model ion cation anion ionic bond

1%r,- Chapter Turo Atoms,Molecutes, and Ions

ionic solid Fo4qation of ions polyatomic ion ', :. Cution-formed by loss of an elecffon, positive charge Section 2.7 i Anion-formed by gain of an electron, negative charge periodic table Ionic bonds-formed by interaction of cations and anions metal ::r nonmetal The periodic table organizes elements in order of increasing atomic group (familY) number. alkali metals r.;:l l.';Flements with similar propgrties,arein columns, or groups. alkaline earth metals r' Metals are in the majority,and riend to form cations halogens r tend to form anions. noble gases Nonmetals period Oompounds are named using a system of rules depending on the type of Section 2.8 , compound. binary compounds r Binary compounds binary ionic compounds ,1'-r.,..llype l-contain a metal that always forms the same cation oxyanions . .'.1 Type ll--contain a metal that can form more than one cation binary covalentcompounds ' Type lll---contain two nonmetals acid r Compounds containing a polyatomic ion

'I'

Answersto theReview Questions can be foundon the Student Web site. ' i. Use Dalton's atomic theory to accountfor each of the following. I a. the law of conservationof mass b. the law of definite proportion c. the law of multipleproportions 2. What evidence led to the conclusion that cathode rays had a negative charge? 3. What discoverieswere madeby J. J. Thomson.Henri Becquerel,and Lord Ruther- I' ford? How did Dalton's model of the atom have to be modified to account for these discoveries? 4. ConsiderErnest Rutherford's alpha-particlebombardment experiment illustrated in Fig. 2.72. How did the resultsof this experimentlead Rutherford away from the plum pudding model of the atom to proposethe nuclear model of the atom? 5, Do the proton and the neutron have exactly the same mass?How do the masses of the proton and neutron compare to the mass of the electron? Which particles make the greatestcontribution to the mass of an atom? Which particles make the greatestcontribution to the chemical properties of an atom? 6. What is the distinction between atomic number and mass number? Between mass numberand atomic mass? 7- Distinguish between the termsfamily and period in connection with the periodic table. For which of these terms is the term group also used? 8. The compoundsAlCl3, CrCl3, and ICl3 have similar formulas, yet each follows a different set of rules to name it. Name these compounds, and then compare and contrast the nomenclature rules used in each case. 9., When metals react with iionmetals, an ionic compound generally results.,What is ' the predicted general formula for the compound formed between an alkali metal !r and sulfur? Between an alkaline earth metal and nitrogen? Between aluminum and ij a halogen? 10. How would you name HBrOo, KIO:, NaBrO2, and HIO? Refer to Thble 2-5 and the acid nomenclaturediscussion in the text. value0f thesequestions is the learningthat 69 A discussionof theActive Learning Ouestions can be found online in lhe peerteaching. The real talk to eachother aboutchemical concepls' lnstructor'sResource Guide and 0n PowerLecture' The questions allow occurswhile students studentsto exploretheir understanding of concepts through discussion and of the following is indi. > Learning 6. The formula of water is HrO. Which Active Questions cated by this formula? Explain your answer' These questions are designedto be used by groups of students in a. the mass of hydrogen is twice that of oxygen in each class. molecule. b. there are two hydrogen atoms and one oxygen atom per water 1. Which of the following is true about an individual atom? Explain' molecule- a. An individual atom should be considered to be a solid' c. the massof oxygen is twice that of hydrogen in eachmolecule' b. An individual atom should be considered to be a liquid' d. there are two oxygen atoms and one hydrogen atom per water c. An individual atom should be consideredto be a gas' molecule. d. The state of the atom dependson which element it is' when water boils, you can see bub- e. An individual atom cannot be consideredto be a solid, liquid, 7, You may have noticed that water' Which of the following or gas. bles that rise to the surface of the Justify your choice, and for choices you did not pick, explain is inside thesebubbles? ExPlain- what is wrong with them. a. air b. hydrogen and oxYgen gas finding the number of "chalk 2. How would you go about c. oxygen gas your name on the board? Provide molecules" it takes to write d. water vaPor you would need to do and a sample an explanation of all e. carbon dioxide gas calculation. 8. One of the best indications of a useful theory is that it raisesmore 3. Thesequestions concern thc work of J. J Thomson' questionsfor further experimentationthan it originally answcred' a. From Thomson'swork, which particlesdo you think he would Does this apply to Dalton's atomic theory? Give examples' for the formation of compounds feel are most important 9. Dalton assumedthat all atoms of the same element were identi- whY? (chemicalchanges) and cal in all their properties-Explain why this assumptionis not valid' b. Of the remainingtwo subatomicparticles, which do you placc l0.Evaluateeachofthefollowingasanacceptablenameforwater: second in importance for forming compounds and why? a. dihydrogen oxide c. hydrogen hydroxide c. Proposethree models that explain Thomson's findings and b. hydroxide hydride d. oxygen dihydride evaluatethem. To be complcteyou shouldinclude Thomson's nitrate' but we call Fe(NO.)2 findings. f 1. Why do we call Ba(NO3)2barium iron(Il) nitrate? 4. Heat is applied to an ice cubc in a closed containeruntil only 12. Why is calcium dichloride not the correct systematic name for steamis present.Draw a representationof this process,assum- CaCl2? ing you can see it at an extremely high level of magnification' What would be the sys- What happensto the sizeof the molecules?What happensto the 13. The corunon namefor NH3 is ammonia' your answer' total massof the samPle? tematic name for NH3? Support 14. Which (if any) of the following can be determined by knowing 5. You have a chemical in a sealed glass container filled with air' thc number of protons in a neutral element?Explain your answer' The setup is sitting on a balance as shown below' The chemical a. the number of neutrons in the neutral element' is ignited by meansof a magnifying glassfocusing sunlight on b. the number of electrons in the neutral element' the reactant. After the chemical has completely burned, which c. the name of the element- of the following is true? Explain your answer' 15. Which of the following explain how an ion is formed? Explain your answer. a. adding or subtracting protons to/from an atom' b. adding or subtracting neutrons to/from an atom' c. adding or subtracting electrons to/from an atom'

A blue questionor exercisenumber indicatesthat the answerto that questionor exerciseappears at the back of this book and a solution appearsin the So/utlonsGuide, as found on Powerlecture'

> Questions 16. What refinements had to be made in Dalton's atomic theory to account for Gay-Lussac's results on the combining volumes of a. The balance will read less than 250.0 g. gases? b. The balance will read 250.0 g. in oxygen to form water, the compo- c. The balance will read greater than 250.0 g. 17. When hydrogen is burned does not depend on the amount of oxygen d. Cannot be determined without knowing the identity of the sition of water formed terms of the law of definite proportion' chemical. reacted. lnterpret this in /l) Chapter Tulo Atoms,Motecutes, and Ions

18. The two most reactive families of elementsare the halogensand a. N2O: nitrogen oxide, nitrogen(I) oxide, dinitrogen monoxide the alkali metals. How do they differ in their reactivities? b. CurO: copper oxide, copper(I) oxide, dicopper monoxide 19. Explain the law ofconservationofmass, the law ofdefinite pro- c. LirO: lithium oxide, lithium(I) oxide, dilithium monoxide portion, and the law of multiple proportions. 20. Section 2.3 describes the postulates of Dalton's atomic theory. > €xercises With some modifications, these postulateshold up very well re- In this section similarexercises are paired. gardinghow we view elements,compounds, and chemicalreac- tions today.Answer the following questionsconceming Dalton's Developmentof the Atomic Theory atomic theory and the modifications made today. a. The atom can be broken down into smaller oarts. What are 31. When mixtures of gaseousHr and gaseousCl, react, a product t 4 the smaller parts? forms that has the same properties regardless of the relative b. How are atoms of hydrogcn identical to each other and how amountsof H, and Clr used. g can they be different from each other? a. How is this result interpreted in terms of the law of definite c. How are atoms of hydrogen different from atoms of helium? proportion? How can H atoms be similar to He atoms? b. When a volume of H2 reactswith an equal volume of Cl, at d. How is water different from hydrogen peroxide (HrOr) even the same temperatureand pressure,what volume of product thoughboth compoundsare composedofonly hydrogenand having the formula HCI is formed? oxygen? 32. A reactionof I liter of chlorine gas (Cl2) with 3 liters of fluo- e. What happensin a chemicalreaction and why is masscon- rine gas (F ) yields 2 liters of a gaseousproduct. All gas vol- servedin a chemicalreaction? umes are at the same temperature and pressure.What is the for- 21. The contributionsof J. J. Thomson and Emest Rutherford led mula of the gaseousproduct? the way to today's understanding of the structure of the atom. 3J] In u .o.bustion reaction,46.0 g of ethanolreacts with 96.0 g of ;l What were their contributions? oxygen to produce water and carbon dioxide. If 54.0 g of water 22. What is the modern view of the structure of the atom? is produced, what. mass of carbon dioxide is produced? 23. The number of protons in an atom determinesthe idcntity of the 34. A sample of chloroform is found to contain 12.0 g of carbon, atom. What does the numbcr and arrangement of the electrons 106.4g of chlorinc, and 1.01g of hydrogen.If a secondsample in an atom determine?What does the number of neutronsin an of chloroform is found to contain 30.0 g of carbon,what is the atom determine? total massof chloroform in the secondsamole? 24. lf the volume of a proton is similar to the volume of an electron, how will the densitiesof these two DarticlescomDare to each 35. Hydrazine,ammonia, and hydrogenazide all containonly nitro- other? gen and hydrogen.The mass of hydrogen that combines with t 25. For lighter, stablc isotopes,the ratio of the mass number to the I .00 g of nitrogenfor eachcompound is 1.44 x I 0 g, 2. 16 x atomic number is close to a certain value. What is the value? l0-r g, and 2.40 x l0-2 g, respectively.Show how thesedata What happensto the value of the massnumber to atomic num- illustratethe law of multiple proportions. ber ratio as stableisotopes become heavier? 36. Consider 100.0-9samples of two different compoundsconsist- 26. List some characteristic properties that distinguish the metallic ing only of carbon and oxygen. One compound contuns 27.2 g elementsfrom the nonmetallicelements. ofcarbon and the other has42.9 gof carbon.How can thesedata 27. Consider the elementsof Group 4^A(the "carbon family"): C, Si, suppon the law of multiple proportionsif 42.9 is not a multiple Ge, Sn, and Pb. What is the trend in metallic character as one of 27.2? Show that thesedata support the law of multiple pro- goes down this group? What is the trend in metallic character Dortlons. going from left to right across a period in the periodic table? 37. Early tablesof atomic weights (masses)were generatedby mea- 28. Distinguish between the following terms. suring the mass of a substancethat reacts with 1.00 g of oxygen. a. moleculeversus ion Given the following data and taking the atomic mass of hydro- b. covalentbonding versusionic bonding gen as 1.00, generatea table of relative atomic massesfor oxy- c. moleculeversus compound gen,sodium, and magnesium. d. anion versus cation 29. Which of the followins statementsare true? For the false state- ments, correct them. Mass That a. Most of the known elements are metals- Gombines with 't.fi) b. Element 118 should be a nonmetal. Element g Orygen Assumed Formula c. Hydrogen has mostly metallic properties. Hydrogen 0.126g HO d. A family of elements is also known as a period of elements. Sodium 2.875g NaO e. When an alkaline earth metal, A, reacts with a halogen, X, Magnesium 1.500g MgO the formula of the covalent compound formed should be A2X. 30. Each of the following compounds has three possible nameslisted for it. For each compound, what is-the correct name and why How do your values compare with those in the periodic table? aren't the other names used? How do you account for any differences? €xercises 71

38. Indium oxide contains 4.784 g of indium for every 1.000 g of a. Ti, Fe, Ag d. Ne, Kr, Xe oxygen. In 1869, when Mendeleev first presentedhis version of b. Mg, Sr, Ba e. F, Br, I the periodic table, he proposed the formula In2O3 for indium c. Li, K, Rb oxide. Before that time it was thought that the formula was InO. 50. Identify the elements that correspond to the following atomic What values for the atomic mass of indium are obtained using numbers. Label each as either a noble gas, a halogen, an alkali these two formulas? Assume that oxygen has an atomic mass metal, an alkaline earth metal, a transition metal, a lanthanide of 16.00. metal, or an actinidemetal. a.17 e.2 The Nature of the Atom b.4 f.92 39. From the information in this chapter on the mass of the proton, c. 63 C. 55 d.'t2 the mass of the electron, and the sizes of the nucleus and the atom, calculate the densitiesof a hydrogen nucleus and a hydro- 51. How many protons and neutrons are in the nucleus of each of gen atom. the following atoms? In a neutral atom of each element, how 40. Ifyou wanted to make an accurate scale model of the hydrogen many electrons are present? atom and decided that the nucleus would have a diameter of a. teBr d. I33cs I mm, what would be the diameter of the entire model? b. 8rBr e. 3H c. '3ePu f. 56Fe 41. In an experiment it was found that the total charge on an oil drop r8 was 5.93 X 10 C. How many negativecharges does the drop 52. What number of protons and neutrons are contained in the nu- contain? cleus of each of the following atoms?Assuming each atom is uncharged,what number of electrons are present? 42. A chemist in a galaxy far, far away performed the Millikan oil a. '#u d.'?!|Pb drop experiment and got the following results for the chargeson b. ';c e. lfnu variousdrops. Use thesedata to calculatethe chargeof the elcc- c. jlre r. tron in zirkombs. lica 53. Write the atomic symbol (2X) for each of the following isotopes. 2.56 x l0 12zirkombs 7.68 x l0 12zirkombs a. Z : 8, number of neutrons= 9 3.84 X l0-'2 zirkombs 6.40 X l0-'3 zirkombs b. the isotopeof chlorine in which A : 3l 43. What are the symbolsof the following metals:sodium, radium, c. Z:27, A: 6O iron, gold, manganese,lead. d. numberofprotons - 26, number ofneutrons : 3l zl4. What are the symbolsof the following nonmetals:fluorine, chlo- e. the isotopeof I with a mass numbcr of 131 : : rine, bromine, sulfur, oxygen, phosphorus? f. Z 3, number of neutrons 4 54. Write the atomic symbol (|Xl for each of the isotopesdescribed 45. Give the names of the metals that correspond to the following below. symbols:Sn, Pt, Hg, Mg, K, Ag. a. number of protons : 27, number of neutrons: 3l 46. Give the names of the nonmetals that correspond to the follow- b. the isotopeof boron with massnumber l0 ing symbols:As, I, Xe, He, C, Si. c. Z: 12,A :23 d. atomic number 53, number of neutrons : 79 47. a. Classify the following elementsas metalsor nonmetals: e. Z : 9, number of neutrons: l0 protons : Mg Si Rn f. number of 29, massnumber 65 Ti Ge Eu 55. For each of the following ions, indicate the number of protons AuBAm and electronsthe ion contains. Bi At Br a. Ba2* e. Co3* b. The distinctionbetween metals and nonmetalsis really not a b. Znz* f. Te2- clear one. Some elements, called metalloids, are intermedi- c. N3 g. Br ate in their properties. Which of these elements would you d. Rb* reclassify as metalloids? What other elementsin the periodic 56. How many protons, neutrons, and electrons are in each of the table would you expect to be metalloids? followins atoms or ions? rE. a List the noble g:ls elements. Which of the noble gases has a. UMc d. ;?co3* c. l?se'- only radioactive isotopes?(This situation is indicated on most b- ?lMc'* e. llco h. t;Ni periodic tables by parenthesesaround the mass of the ele- c. llco2* r. lfSe i. tft{F* ment. See inside front cover.) What is the symbol for an ion with 63 protons, 60 electrons, and b. Which lanthanide element and which transition element have 88 neutrons? If an ion contains 50 protons, 68 neutrons, and only radioactive isotopes? 48 electrons, what is its symbol? 49. For each of the following sets of elements, label each as either 58. What is the symbol of an ion with 16 protons, 18 neutrons, and noble gases, halogens, alkali metals, alkaline earth metals, or 18 electrons?What is the symbol for an ion that has 16 protons, transition metals, 16 neutrons,and 18 electrons? Chapter Turo Atoms, Motecutes,and Ions

59. Complete the following table: 66. Write the formula for each of the following compounds: a. zinc chloride d. aluminum sulfide b. tin(IV) fluoride e. mercuryfl) selenide Number ol Number of c. calcium nitride f. silver iodide Protons in Neutrons in Number of Net Symbol Nucleus Nucleus Electrons Charge 67. Name each of the following compounds: a. BaSOI c. KMnOa "r|u b. NaNO2 d. K2Cr2O7 20 20 2+ 68, Write the formula for each of the following compounds: 23 28 20 a. chromium(Ill) hydroxide c lead(IV) carbonate !3Y b. magnesium cyanide d. ammonium acetate 35 36 69. Name each of the following compounds: l5 l6 3- a. oo 9N 60. Completethe following table: "€b Number of Number of Protons in Neutrons in ?: Number of Net c. SO2 Symbol Nucleus Nucleus Electrons Charge d. P2s5 12p"'* 70. Write the formula for each of the following compounds: 26 33 3+ a. diboron trioxide c. dinitrosen monoxide b. arsenic pentafluoride 85 125 86 d. sulfur hexachloride l3 T4 10 71. Name each of the following compounds: '76 54 a. CuI f. s4N4 b. CuI2 8. SFr c. CoI, h. NaOCI d. Na2CO3 i. BaCrOo 61. Would you expecteach of the following atoms to gain or lose e. NaHCO3 j. NH4NOI electronswhen forming ions?What ion is the most likely in each case? 72. Name each of the following compounds.Assume the acids an a.Ra c.P e.Br dissolvedin water. b. In d. Te f. Rb a. HCrH,O, g. HzSOo b. NH4NO2 h. SrrN, 62. For each of the following atomic numbers,use the periodic table c. Co2S3 i. A12(s03)3 to write the formula (including the charge) for the simple ion d. ICI j. SnO2 that the elementis most likely to form in ionic compounds. e. P\(POa)2 k. NarCrOo a. 13 c. 56 e. 87 f. Kclo3 t. HClo b.34 d.] f.35 73. Elements Nomenclature in the same family often form oxyanions of the samt generalformula. The anionsare named in a similar fashion. Wha 63. Name the compoundsin parts a-d and write the formulas for the are the names of the oxyanions of selenium and tellurium 'leo..2 compounds in parts e-h. Seoo2 , Seo32-, Teoo2-, ? a. NaBr e. strontium fluoride 74. Knowing the namesof similar chlorine oxyanions and acids, de. b. RbzO f. aluminum selenide duce the namesof the following: IO-, IO2-, IO3-, IO4-, HIO c. CaS g. potassium nitride HIO2, HIO3, HIO4. d. AlI3 h. magnesium phosphide 64. Name the compoundsin parts a-d and write the formulas for the 75. Write the formula for each of the following compounds: compounds in parts e-h. a. sulfur difluoride a. HgrO e. tin(Il) nitride b. sulfur hexafluoride b. FeBr3 f. cobalt(Ill) iodide c. sodium dihydrogen phosphate c. CoS g. mercuryflI) oxide d. lithium nitride d. TiCl4 h. chromium(Vl) sulfide e. chromium(Ill) carbonate f. tin(Il) fluoride 65. Name each of the following compounds: g. arnmonium acetate a. CsF c. AgrS e. TiO2 h. ammonium hydrogen sulfate b. Li3N d. MnO2 f. Sr3P2 i. cobalt(Ill) nitrate Additional.€xercises 73

diacetate j. mercury(I) chloride e. Mg(C2H3Or)r, manganese phosPhide k. potassium chlorate f. FePOa,iron(Il) sulfide l. sodium hydride B. PzSs,phosphorus h. NarOr.sodium oxide 76. Write the formula for each of the following compounds: i. HNO3, nitrate acid a. chromium(Vl) oxide j. HtS, sulfuric acid b. disulfur dichloride c. nickel(Il) fluoride d. potassium hydrogen PhosPhate > Biochemistrg e. aluminum nitride Connecting to f. ammonia 81. Carbon-l4 dating is a methodused to determinethe age of his- g. manganese(lV) sulfide torical artifacts by examining the ratio of two isotopes of carbon h. sodium dichromate (carbon-14 and carbon-12). A living plant consumescarbon diox- i. ammonium sulfite ide in the photosynthesisprocess and incorporatesthe carbon' t'C, j. carbon tetraiodide including into its molecules-As long as a plant lives, the -7f$n" loC/'2Cratio in its moleculesremains the sameas in the atmos- each of the following compounds: the formula for phere becauseof its continuousuptake of carbon' Howeveq as h. copper(I)chloride a. sodium oxide soon as a tree is.cut to make a wooden bowl or a flax plant is peroxide i. gallium arsenidc laC/r2C b. sodium harvestedto make linen, the ratio begins to decreasebe- j. cadmium selenidc rac c. potassiumcYanide causeof the radioactivedecay of (r2Cis stable).By compar- k. zinc sulfide IaClr2C d. copper(Il) nitrate ing the cunent ratio to the presumedratio when the ar- l. nitrous acid e. seleniumtetrabromide tifact was made, one can estimate the age of the artifact' F-or m. diphosphorus f. iodous acid Pentoxide carbon-I4 and carbon-I2, how many protons and neutronsare g. lead(IV) sulfide in each nuclcus?Assuming neutral atoms,how many electrons 78. Write the formula for each of the fbllowing compounds: are presentin an atom of carbon-14 and in an atom of carbon-I 2? a. ammonium hydrogenPhosphate 82. What are the symbols for the following nonmetal elements that b. mercury(I) sulfide are most often presentin compoundsstudied in organic chem- c. silicon dioxide istry: carbon, hydrogen, oxygen, nitrogen' phosphorus,sulfur' d. sodium sulfite Predicta stableisotope for each of theseelements' e. aluminum hydrogen sulfate tl3. Four Ire2+ions are key componentsof hemoglobin,the protein f. nitrogen trichloride that transportsoxygen in the blood-Assuming that theseions are hydrobromic acid c. 5lFe2*, h,rw many protons and neutrons are present in each h. bromous acid nucleus,and how many electronsare presentin each ion? i. perbromic acid class of compoundscontaining the elements j. potassiumhydrogen sul{ide 84. Carbohyctrates,a and oxygen, were originally thought to con- k. calcium iodide carbon,hydrogen, water molecule (H2O) for each carbon atom present' t. cesium perchlorate tain one The carbohydrateglucose contains six carbon atoms' Write a 79. Name the acids illustrated below. general formula showing the relative numbers of each type of atom presentin glucose- 85. The vitamin niacin (nicotinic acid, C6H5NO2)can be isolated from a variety of natural sources such as liver, yeast, milk, and whole grain. It also can be synthesizedfrom commercially avail- p % able materials. From a nutritional point of view' which source of b. nicotinic acid is best for use in a multivitamin tablet? Why? 86. Give the systematicname for the following compoundsthat are db- EH (fc Fn found in everydaYlife. 4a 9N eil @s a. H2S (rotten egg smell) eo (smell burnt matches) fi,Ea b. SO2 of ffi-!-- € Sn c. SFu (aerosol can ProPellant) 61", d. Na2SO3(dried fruit preservative) d.

80. Each of the following compounds is incorrectly named. What is > Additional €xercises wrong with each name, and what is the correct name for each re- compound? 87. Chlorine has two natural isotopes: l]Ct anA ]fcl. ttydrogen HCl. Would a given a. FeCl3, iron chloride acts with chlorine to form the compound massesof the two chlo- b. NO2, nitrogen(IV) oxide amount of hydrogen react with different the law of definite propor- c. CaO, calcium(Il) monoxide rine isotopes?Does this conflict with d. AlzSr, dialuminum trisulfide tion? Why or whY not?

H