Chapter4AtomicStructureTheNuclearAtomTheAtomasthe.ppt

Chapter4:hargeoildropexperimentsq=nee/m=>massofelectronsneutralatomsas“natural”state“PlumPudding”model BUT.....------Rutherfordscattering(alphaparticlesfromheavynuclei)=testof“plumpudding”modelaalphaparticlesemittedinsomeradioactivedecaysspeeds~2E7m/sq=+2e,m~8000xme(aisaHe4nucleus)alphasourceleadcollimatorthinfoillightflash------Expected(fromplumpudding):smallscatteringangles,nobackscatteringResults:somelargerscatteringangles,includingsomebackscatteringTheNuclearAtom:smallheavynucleus(%ofatom’smass)harge~1/100,000radiusofatomelectron“cloud”=>electronsorbitnucleusRutherfordScattering(theoreticalresults):Rutherford’singredients:NewtonianMechanics(F=ma)CoulombInteraction=>DistanceofclosestapproachExample:?(ZAu=79)ElectronOrbits:arymodelsoftheatomforthepurposesofthisdiscussion,takeelectronorbitstobecircularHydrogen::(theenergyrequiredtoliberatetheelectronfromtheatom).:acceleratingchargesradiateorbitscannotbestable!!considerableproblemswithatomicspectraAtomicSpectraemissionlinespectra(fromthin,hotgasorvapor):patternsinthespectraBohrAtomelectroninorbitaboutnucleusatomicsize~electronorbitradius()=