observing bright line spectra：观察亮线光谱.doc

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1、Name：ClassPeriod：LabPartnerLabPartnerLab#5ObservingBrightLineSpectraPROBLEMWhatevideneeindicatesthatelectronsmovearoundthenucleusindefinitepathways?INTRODUCTIONThequantummodeloftheatom,proposedbyNielsBohrin1913,suggeststhatelectronsmovearoundthenucleusoftheatomindefinitepath

2、ways・Thefurthertheelectron'spathisfromthenucleus,themoreenergytheelectronhas・Theelectronspathiscalledanenergylevel.Electronscanmovetohigherenergylevelsiftheypickupenoughenergy,buttheycannotbefoundbetweenenergylevels・Bohrreachedthisconclusionbyexaminingthelightgivenoffbyelect

3、ronsastheyfellfromhighenergylevelsbacktotheirnaturalgroundstate.Inhislabelectronsareexcitedbypassinganelectriccurrentthroughagaseoussampleinadischargetube.Whenthegasisexcitedthetubewillglowbrightly.Thisglowisproducedwhenexcitedelectronsemitradiantenergyastheyreturntotheirgro

4、undstate.White,lightcanbeseparatedintodifferentcolorsasinarainbow・Differentcolorsoflighthavedifferentenergies・Arainbowhasallthecolorsorenergiesoflightinthevisiblespectrum・Inthislaboratoryexercise,youwilluseaspectroscopetoexaminethelightgivenoffbyseveraltubesofgas,eachcontain

5、ingthevaporofapureelement.Anemissionspectrumorbrightlinespectrumwillbeproducedinwhichyouwillseespectrallines.Eachelementhasitsownuniquebrightlinespectrumbywhichitcanbeidentified.Thisconsistsofbrightlinesatadefinitewavelength.Eachwavelengthcanbemathematicallyrelatedtoadefinit

6、equantityofenergyproducedbythemovementofanelectronformonediscreteenergyleveltoanotherusingPlanck'sformula,E=hfandtheformularelatingwavelengthandfrequency,f+c/ATherefore,brightlinespectraprovethatelectronsexistatdefiniteanddistinctiveenergylevelsintheatom,MATERIALS(perqrouu)G

7、astubes;powersupply;spectroscopePROCEDURE1.Examineasourceofwhitelightthroughaspectroscope•Lookaroundinthespectroscopeuntilyoufindthespectrum(arainbowofcolors).Turnyourslidesothespectrumextendstobothsidesofthelightsourceratherthanaboveandbelow.2.Yourteacherwillputgastubesinto

8、thepowersupplyandturnthemonforyou.Usethespectroscopetoexaminethespectrumemi