英文化学元素周期表.docx
- 文档编号:23016576
- 上传时间:2023-04-30
- 格式:DOCX
- 页数:9
- 大小:48.85KB
英文化学元素周期表.docx
《英文化学元素周期表.docx》由会员分享,可在线阅读,更多相关《英文化学元素周期表.docx(9页珍藏版)》请在冰豆网上搜索。
英文化学元素周期表
ThePeriodicTableofElements
byAnthonyCarpi,Ph.D.
In1869,theRussianchemistDmitriMendeleevfirstproposedthatthechemicalelementsexhibiteda"periodicityofproperties." Mendeleevhadtriedtoorganizethechemicalelementsaccordingtotheiratomicweights,assumingthatthepropertiesoftheelementswouldgraduallychangeasatomicweightincreased. Whathefound,however,wasthatthechemicalandphysicalpropertiesoftheelementsincreasedgraduallyandthensuddenlychangedatdistinctsteps,orperiods. Toaccountfortheserepeatingtrends,Mendeleevgroupedtheelementsinatablethathadbothrowsandcolumns.
ThemodernperiodictableofelementsisbasedonMendeleev'sobservations;however,insteadofbeingorganizedbyatomicweight,themoderntableisarrangedbyatomicnumber(z). Asonemovesfromlefttorightinarowoftheperiodictable,thepropertiesoftheelementsgraduallychange. Attheendofeachrow,adrasticshiftoccursinchemicalproperties.Thenextelementinorderofatomicnumberismoresimilar(chemicallyspeaking)tothefirstelementintherowaboveit;thusanewrowbeginsonthetable.
Forexample,oxygen(O),fluorine(F),andneon(Ne)(z=8,9and10,respectively)allarestablenonmetalsthataregasesatroomtemperature.Sodium(Na,z=11),however,isasilvermetalthatissolidatroomtemperature,muchliketheelementlithium(z=3).Thussodiumbeginsanewrowintheperiodictableandisplaceddirectlybeneathlithium,highlightingtheirchemicalsimilarities.
Rowsintheperiodictablearecalledperiods. Asonemovesfromlefttorightinagivenperiod,thechemicalpropertiesoftheelementsslowlychange. Columnsintheperiodictablearecalledgroups. Elementsinagivengroupintheperiodictablesharemanysimilarchemicalandphysicalproperties. Thelinkbelowwillopenacopyoftheperiodictableofelementsinanewwindow.
ThePeriodicTableofElements
ElectronConfigurationandtheTable
The"periodic"natureofchemicalpropertiesthatMendeleevhaddiscoveredisrelatedtotheelectronconfigurationoftheatomsoftheelements.Inotherwords,thewayinwhichanatom'selectronsarearrangedarounditsnucleusaffectsthepropertiesoftheatom.
Bohr'stheoryoftheatomtellsusthatelectronsarenotlocatedrandomlyaroundanatom'snucleus,buttheyoccurinspecificelectronshells(seeourAtomicTheoryIImoduleformoreinformation).Eachshellhasalimitedcapacityforelectrons.Aslowershellsarefilled,additionalelectronsresideinmore-distantshells.
Thecapacityofthefirstelectronshellistwoelectronsandforthesecondshellthecapacityiseight.Thus,inourexamplediscussedabove,oxygen,witheightprotonsandeightelectrons,carriestwoelectronsinitsfirstshellandsixinitssecondshell.Fluorine,withnineelectrons,carriestwoinitsfirstshellandseveninthesecond.Neon,withtenelectrons,carriestwointhefirstandeightinthesecond.Becausethenumberofelectronsinthesecondshellincreases,wecanbegintoimaginewhythechemicalpropertiesgraduallychangeaswemovefromoxygentofluorinetoneon.
Sodiumhaselevenelectrons.Twofitinitsfirstshell,butrememberthatthesecondshellcanonlycarryeightelectrons.Sodium'seleventhelectroncannotfitintoeitheritsfirstoritssecondshell.Thiselectrontakesupresidenceinyetanotherorbit,athirdelectronshellinsodium.Thereasonthatthereisadramaticshiftinchemicalpropertieswhenmovingfromneontosodiumisbecausethereisadramaticshiftinelectronconfigurationbetweenthetwoelements.Butwhyissodiumsimilartolithium?
Let'slookattheelectronconfigurationsoftheseelements.
GroupIA
VIA
VIIA
VIIIA
Lithium
Oxygen
Fluorine
Neon
Sodium
ElectronConfigurationsforSelectedElements
Asyoucanseeintheillustration,whilesodiumhasthreeelectronshellsandlithiumtwo,thecharacteristictheyshareincommonisthattheybothhaveonlyoneelectronintheiroutermostelectronshell.Theseouter-shellelectrons(calledvalenceelectrons)areimportantindeterminingthechemicalpropertiesoftheelements.
Anelement'schemicalpropertiesaredeterminedbythewayinwhichitsatomsinteractwithotheratoms.Ifwepicturetheouter(valence)electronshellofanatomasasphereencompassingeverythinginside,thenitisonlythevalenceshellthatcaninteractwithotheratoms-muchthesamewayasitisonlythepaintontheexteriorofyourhousethat"interacts"with,andgetswetby,rainwater.
Lithium
Sodium
Anatom'svalenceshell
"covers"innerelectronshells
Thevalenceshellelectronsinanatomdeterminethewayitwillinteractwithneighboringatoms,andthereforedetermineitschemicalproperties.Sincebothsodiumandlithiumhaveonevalenceelectron,theysharesimilarchemicalproperties.
ElectronConfigurationShorthand:
ForelementsingroupslabeledAintheperiodictable(IA,IIA,etc.),thenumberofvalenceelectronscorrespondstothegroupnumber.ThusLi,Na,andotherelementsingroupIAhaveonevalenceelectron.Be,Mg,andothergroup-IIAelementshavetwovalenceelectrons.B,Alandothergroup-IIIAelementshavethreevalenceelectrons,andsoon.Therow,orperiod,numberthatanelementresidesinonthetableisequaltothenumberoftotalshellsthatcontainelectronsintheatom.HandHeinthefirstperiodnormallyhaveelectronsinonlythefirstshell;Li,Be,B,andotherperiod-twoelementshavetwoshellsoccupied,andsoon.Towritetheelectronconfigurationofelements,scientistsoftenuseashorthandinwhichtheelement'ssymbolisfollowedbytheelement'selectronshells,writtenasaright-handparenthesessymbol")".Thenumberofelectronsineachshellisthenwrittenafterthe)symbol.Afewexamplesareshownbelow.
Element
ConfigurationShorthand
Hydrogen
H)1e-
Lithium
Li)2e-)1e-
Fluorine
F )2e-)7e-
Sodium
Na)2e-)8e-)1e-
Forfurtherdetails,thetablelinkedbelowshowstheelectronconfigurationsofthefirstelevenelements.
()
PeriodicTableofElementsQuiz
"ThePeriodicTableofElements"Module
Visionlearning-aninteractivepracticeexercise.
窗体顶端
(1)DmitriMendeleevorganizedthechemicalelements:
(a)byincreasingatomicnumberandsimilarproperties
(b)byincreasingatomicweightandsimilarproperties
(c)bynumberofelectrons
(d)inalphabeticalorder
(2)Theelementsinthepresentperiodictablearearrangedaccordingtotheir:
(a)atomicmasses
(b)atomicnumber
(c)atomicweight
(d)massnumber
(3)Averticalcolumnintheperiodictableiscalleda:
(a)branch
(b)group
(c)period
(d)valence
(4)Ahorizontalrowintheperiodictableiscalleda:
(a)branch
(b)group
(c)period
(d)shells
(5)Themajorityoftheelementsintheperiodictableare:
(a)metalloids
(b)metals
(c)noblegases
(d)nonmetals
(6)WhatdoesBohr'stheorystate?
(a)Electronsarelocatedrandomlyaroundanatom'snucleus
(b)Electronsdon'toccuratallinatoms
(c)Electronsoccuraroundthenucleusinelectronshellsthathavealimitedcapacity
(d)Electronsoccurinshellsofunlimitedcapacity
(7)Whatisthecapacityofthefirstelectronshell?
(a)eight
(b)sixteen
(c)three
(d)two
(8)Whichofthefollowingistheelectronconfigurationforcarbon:
(a)C)2e-)4e-
(b)C)2e-)6e-
(c)C)2e-)8e-)2e-
(d)Ca)2e-)8e-)2e-
(9)Elementsinthesomegrouphave:
(a)similarsymbols
(b)thesamenumberofelectrons
(c)thesamenumberofneutrons
(d)thesamenumberofvalenceelectrons
(10)Elementsinthesameperiodhave:
(a)graduallychangingproperties
(b)identicalchemicalproperties
(c)similarsymbols
(d)thesamenumberofneutrons
(11)Whichelementisclassifiedasmetalloid?
(a)Ca
(b)Cl
(c)Si
(d)Zn
(12)Howmanyvalenceelectronsdoescalciumhave?
(a)eight
(b)one
(c)twenty
(d)two
(13)Howmanyvalenceelectronsdoesboronhave?
(a)four
(b)one
(c)three
(d)two
窗体底端
(注:
可编辑下载,若有不当之处,请指正,谢谢!
)
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 英文 化学元素 周期表