Atoms

&

thePeriodicTableMatter

Anythingthathasmassandvolume(takesupspace)PureSubstance

Atypeofmatterwithafixedcomposition.Allofparticlesthatmakeupthissubstancearealike.PureSubstanceElement–Asubstancethatcannot

bebrokendownintosimplersubstancesbyordinarymeans(heatingoranychemicalprocess).90naturallyoccurringelements.ArrangedinanorderonPeriodicTableTheatomTheGreekModel1.Democritus–Greekphilosopherwhotheorizedaboutwhethermattercouldbedividedintosmallerandsmallerpieces.A.Concludedthatmattercouldnotbedividedintosmallerandsmallerpiecesforever.B.Namedthesmallestpiecesofmatter–Atom.TheatomTheGreekModelDemocritus

2.Hypothesized–Atomswereinfiniteinnumber,alwaysmoving,andcapableofjoiningtogether.3.Notwidelyaccepted–Couldnotprovetheories.TheatomAtom–Thesmallestparticleofanelementthathasthepropertiesofthatelement.BasicbuildingblocksofmatterDalton’sModelJohnDalton–Englishchemist

BasicIdeasofDalton’sAtomicTheory:A.Allelementsarecomposedofatoms–Atomsareindivisibleandindestructibleparticles.–SimilartoDemocritusB.Atomsofthesameelementareexactlyalike.Dalton’sModelBasicIdeasofDalton’sAtomicTheory(con’t):C.Atomsofdifferentelementsaredifferent.D.Compoundsareformedbythejoiningofatomsof2ormoreelements.

FoundationofmodernchemistryThomson’sModelJ.J.Thomson–Englishchemist

1.BasicIdeaofThomson’sModelA.Atomsaremadeofevensmallerparticles.B.Studiedthepassageofanelectriccurrentthroughagas–Gasgaveoffraysthatweremadeofnegativelychargedparticles-CorpusclesToday–ElectronsThomson’sModel2.Atomsthoughttohaveaneutralcharge–Findingelectronschangedidea.A.Thomsonunabletoshowparticlesthathadapositivecharge.

3.Proposedamodelofanatom–PlumPuddingPlumPuddingTheatomwasmadeofapudding-likepositivelychargedmaterialthroughoutwhichnegativelychargedelectronswerescattered,likeplumsinapudding.QUESTIONWhatarethesignificantdifferencesbetweenDalton’smodelandThomson’smodeloftheatom?AtomwasnotasingleparticleItwasmadeofpositiveandnegativeparticlesRutherford’sModelErnestRutherford–Englishphysicist.

1.Rutherford’sExperiment–A.Firingastreamoftinypositivelychargedparticlesatthinsheetofgoldfoil.Rutherford’sModel1.Rutherford’sExperiment–B.Mostofthepositivelycharged“bullets”passedthroughthegoldatomsinthesheetoffoil.C.Some“bullets”didbounceawayfromthegoldsheetsasiftheyhadhitsomethingsolid–Somebouncedstraightback.

Conclusion:Atommusthaveasmall,dense,positivelychargedcenter–NucleusRutherford’sModel2.Rutherford’sTheoryTwopartsofanatom:A.Allofanatom’spositivelychargedparticleswerecontainedinthenucleus.B.Thenegativelychargedelectronswerescatteredoutsidethenucleusaroundtheatom’sedge.Rutherford’sModel2.Rutherford’sTheoryC.Betweenthenucleusandtheelectronswasmostlyemptyspace.D.Negativelychargedelectronswereheldinanatombytheattractionbetweenthemandthepositivelychargednucleus.QUESTIONWhatarethesignificantdifferencesbetweenThomson’smodelandRutherford’smodeloftheatom?Themassoftheatomisatthecenteroftheatominsteadofthroughouttheatomelectronsorbitthenucleus.BohrModelNielsBohr–Danishscientist.

1.Proposedthelocationofelectrons.

BohrModelB.Theorbits,orenergylevels,arelocatedatcertaindistancesfromthenucleus.4.Workedinexplainingthestructureandbehaviorofsimpleatoms–Notcomplexatoms2.Bohr’sTheory–A.Electronsmoveindefiniteorbitsaroundthenucleus.QUESTIONWhatarethesignificantdifferencesbetweenRutherford’smodelandtheBohrmodeloftheatom?Theorbitsoftheelectronsarenotrandombutarefixeddistancesfromthenucleus.ProtonsandneutronsareinthenucleusElectronCloudModelModernatomicmodelA.Electronsdonotmoveaboutanatominadefinitepath Canonlypredictwhereanelectronismostlikelytobefound.B.Atomhasasmallpositivelychargednucleussurroundedbyalargeregioninwhichthereareenoughelectronstomaketheatomneutral.Atom–NucleusMakesupabout99%oftheatomicmassA.Protons–Positivecharge (1)Thenumberofprotonsdetermineswhattheelementis. (2)Protonnumbersneverchange.Atoms–Nucleus(3)AtomicMassUnit(amu)–Unitusedtomeasuretherelativemassesofsubatomicparticles; Aprotonhasamassof1amu.(4)AtomicNumber–Indicatesthenumberofprotonsfoundinthenucleusofanatom.Atoms–NucleusNeutrons–Neutralcharge(1)Neutronnumberscanchange.

Isotopes–Atomsofthesameelementthathavethesamenumberofprotonsbutdifferentnumbersofneutrons.Atoms–NucleusNeutrons–Neutralcharge(2)MassNumber–Thesumoftheprotonsandneutronsfoundinnucleusofanatom.(a)Determiningthenumberofneutrons–SubtracttheAtomicNumberfromtheMassNumber(roundthenumber)Atom-ElectronCloudMakesupabout99%oftheatomicvolume.A.Electrons–Negativecharge(1)Thearrangementofelectronsdeterminesthechemicalpropertiesofanelement.(a)DeterminesthebondingabilityofanatomB.EnergyLevels–Representsthemostlikelylocationintheelectroncloudinwhichanelectroncanbefound.Atom-ElectronCloudB.EnergyLevels–(1)Eachenergylevelcanholdonlyacertainnumberofelectrons– (a)1stLevel - 2 (b)2ndLevel - 8 (c)3rdLevel - 18 (d)4thLevel - 32 (e)5thLevel - 50 (f)6thLevel - 72Atom-ElectronCloudValenceElectrons–Electronsfoundintheouterenergylevelofanatom.(a)Canhaveamaximumof8electronsintheouterenergylevel.ThePeriodicTableThenumberatthetopOneortwolettersinthecenteroftheboxBelowthechemicalsymbolThenumberatthebottom1.AtomicNumber2.ChemicalSymbol3.Name4.AtomicMassThePeriodicTableForcesWithinanAtom

Forcesthataccountforthebehaviorofsubatomicparticles.ElectromagneticForceA.Forcethatwilleitherattractorrepeltheparticlesonwhichitacts.(1)Particleshavingthesamecharge–repel(2)Particleshavingdifferentcharges–attractForcesWithinanAtom

Forcesthataccountforthebehaviorofsubatomicparticles.ElectromagneticForceB.Keepelectronsinorbitaroundthenucleus–Negativelychargedelectronsareattractedtothepositivelychargednucleus.ForcesWithinanAtom

Forcesthataccountforthebehaviorofsubatomicpa