化学专业英文回答问题.doc

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1、作文；1、周期表Eachhorizontalrowofelemc^ntsconstitutesaperiod.Itshouldhenotedthatthelengthsoftheperiodsvary.Thereisaveryshortperiodcontainingonly2elements,followedbytwoshortperiodsof8elementseach,andthentwolongperiodsof18elementse

2、

3、hemembersoftheothergroupsarecalledtransitionorinnertransitionelements.Intheperiodictable,aheavystepped1inedividestheelementsintometcils“ndnonmetals.Elementstotheleftofthisline(withtheexceptionofhydrogen)aremetals,whi1ethosetotherightarenonmetals.Thisdivisionis

4、forconvcnienceonly;elementsborderin£the1ine一thenw^talloids^havepropertieschamcteristicof一bothmetalsandnonmetalItmaybeseenthatmostoftheelements,includingal1thetransition“ndinnertransitionelements,aremetals.Experimental(PrepkimtionofNylon6—10)Placeasolutionof2.0

5、ml.ofsebacoylchloridein100ml.ofcurbontetrachlorideina200-ml.tail・fonnbeaker.Overtheacidchloridesolutioncarefullypourasolutionof2.2g.of1iexamethylcnedicunine“nd1.5g.ofsodiumhydroxidein50ml.ofwaiter.Theadditionofthediamino-sudiumhydroxidesolutionisbestdonebypour

6、ingthesolutionthroughafunnelplacedsothatitsoutletisjustoverthesurfaceofthediacidsolution.Graspthepolymericfilmwhichformstittheinterfaceofthetwosolutionswithforcepsandseitfromthebeakerascontinuouslyformingrope.Tfamechanicalwindupdeviceisplacedabovethebeaker,the

7、polymermayhewoundupcontinuouslyuntiloneofthereaettintsisexhiiustcd.Washthepolymerthoroughlywithwatercindfintillywith50%ticetonesolution.AllowtheWcishedpolymerto

8、ingtakennottocharthepolymer1.Touch