Atoms, Molecules, and Lons

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 reactions 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 substance coppercarbonate

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