大學(xué)物理西爾斯

Introduction：1)thequantumtheory

In1900，Plankputforwardtheconceptofquantum,explainingtheblack-bodyradiation,whichlaidfoundationtothequantumtheory.

In1905，Einsteinexplainedthephotoelectric

effectbytheconceptofphoton,whichledthe

thequantumtheorytoanewstage;

In1920~1926，thediscoveryandanalysisof

Comptoneffectprovedthetheoryofphotontobecorrect.Thetheoreticalanalysiscoincidedexperimentsperfectly.§28-3HydrogenAtomiclineSpectraandenergylevels3)electronIn1897，J.J.Thomsondiscoveredelectron,leadingpeopletothemicroworld.WhatQuantumphysicsNewtonianmechanicsforMicroworldelectronWiththedevelopmentofspectroscopypeoplerealizedthatspectraactuallydiscovertheinteriorstructureofatoms.2)SpectrumatomelectronElectronisnegativelycharged.Itsmassisaboutonetwo-thousandthofthatofHydrogenatom.electricneutralityQ1：Theremustbesomethingwithpositivechargeintheatom.Howdoesthemassoftheatomdistribute?Q2：Howdoesthechargesoftheatomdistribute?1)AtomicSpectra：emissionspectrum：thespectrumformedduringtheprocessofradiationofelectromagneticwaves.absorptionspectrum：thespectrumformedduringtheprocessofabsorptionofelectromagneticwaveswithcertainwavelengths.1.AtomicSpectraofHydrogenExperimentsshowthattheemissionspectrumiscorrespondingtoabsorptionspectrum：Differentatomshavedifferentspectrawhicharethecharacteristictoidentifytheatoms.Featureoftheatomspectra:linespectra

BalmerseriesHa：656.210nmHb：486.074nmHg：434.010nmHd：410.120nmWecangetfourlineswithinthevisiblelightinanelectricdischargetube.條In1885theSwissteacherJohannBalmerfoundformulathatgivesthewavelengthofthreelines,whicharenowcalledtheBalmerseries.LimitofwavelengthofBalmerseries1890:RydbergconstantAtomicSpectraofHydrogenLymanseries:

UVPaschenseries:

visiblelight

Brackettseries:near-infraredPfundseries:

Similarregularityhasbeenfoundinthespectraofatomsofotherelements.2.RulesofAtomicSpectraunifiedformula

Atomshavelinespectrum；

Thereissomerelationshipbetweeneveryline;Thewavenumberofeachlinecanbeexpressedbythedifferenceoftwospectralterms.Experimentsshowthat:Ritzcombinationprinciple：Thewavenumberofanylinespectrumcanbeexpressedbythedifferenceoftwospectraltermswhichcomesfromthemanyinherentspectraltermsoftheelement.(ThiswasdiscoveredbyRitzin1908.)3.Energylevels:1913,Bohr

Theline

spectrumofanelementresultsfrom

theemissionofphotonswithspecificenergiesfromtheatomsoftheelement.

duringtheemissionofaphoton,theinternal

energyofanatomchangesbyanamountequaltotheenergyofthephoton.

Eachatommustbeabletoexistonlywithcertainspecificvaluesofinternalenergy----energylevel.1)Ground-statelevel:Everyatomhasalowestenergylevelthatincludestheminimuminternalenergystatethattheatomcanhave.2)Excitedlevel:Allhigherlevelsarecalledexcitedlevel.AphotoncorrespondingtoaparticularSpectrumlineisemittedwhenanatommakesatransitionfromastateinanexcitedleveltoastateinalowerexcitedlevelorthegroundlevel.3)

Lifetime:

Theaveragetimespentinanexcitedleveliscalledthelifetimeofthelevel.4)absorptionspectrum:Ingeneral,aphotonemittedwhenanatommakesatransitionfromanexcitedleveltoalowerlevelcanalsobeabsorbedbyasimilaratomthatisinitiallyinalowerlevel.玻爾（NielshenrikDavidBohr，1885-1962）

丹麥理論物理學(xué)家，現(xiàn)代物理學(xué)的創(chuàng)始人之一。在1913年發(fā)表了《論原子結(jié)構(gòu)與分子結(jié)構(gòu)》等三篇論文，提出了在盧瑟福原子有核模型基礎(chǔ)上的關(guān)于原子穩(wěn)定性和量子躍遷的三條假設(shè)，從而圓滿地解釋了氫原子的光譜規(guī)律。玻爾的成功，使量子理論取得重大發(fā)展，推動(dòng)了量子物理的形成，具有劃時(shí)代的意義。玻爾于1922年12月10日諾貝爾誕生100周年之際，在瑞典首都接受了當(dāng)年的諾貝爾物理學(xué)獎(jiǎng)金。1937年，他來(lái)中國(guó)作學(xué)術(shù)訪問(wèn)，表達(dá)了對(duì)中國(guó)人民的友好情誼。Thepositivechargesandthemassoftheatomdistributeuniformlyinaspherewiththeradius10-10m,andtheelectronsareimmersedinthesphere.1)Thomsonmodel：raisins-cakemodel1.Twoimportantmodelsforatoms:§28.4thenuclearatom1903:J.J.Thomson

Itcannotexplainwhythepositiveandnegtive

chargesdonotneutralize;Itcannotexplainthepresenceofseriesofthehydrogenspectrum；

Itcannotexplainthelarge-anglescatteringofα-particles.Limitation:

Scatteringofα-particle:RSOFPTθMostα-particlesarescatteredthroughonlyasmallanglewhenpassingthroughthegoldfoil.Afewα-particlesarescatteredthroughananglegreaterthan900，evennearly1800.Theexperimentoflarge-anglescatteringofα-particlesprovedtheThomson’smodelincorrect.2)thenuclearatomPlanetmodelofatomelectronThepositivechargesallconcentratedinasmallspace-----nucleus.Itoccupiesonlyabout10-12ofthetotalvolumeoftheatomorless.Itcontainsmorethan99%ofthetotalmassoftheatom.Electronsrevolvearoundthenucleus.Thismodecanexplainthelarge-anglescatteringofα-particles.1911:RutherfordAccordingtoclassicalphysics,theelectronwithanaccelerationshouldradiateelectromagneticwaves.Thefrequencyoftheelectromagneticwavesshouldequalth