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02.THENONMETALELEMENTSWenotedearlier.that-nonmetalsexhibitpropertiesthataregreatlydifferentfromthoseofthemetals.Asarule,thenonmetalsarepoorconductorsofelectricity(graphiticcarbonisanexception)andheat;theyarebrittle,areoftenintenselycolored,andshowanunusuallywiderangeofmeltingandboilingpoints.Theirmolecularstructures,usuallyinvolvingordinarycovalentbonds,varyfromthesimplediatomicmoleculesofH2,Cl2,I2,andN2tothegiantmoleculesofdiamond,siliconandboron.我们前面提到的。-非金属表现出的性质有很大的不同，这些金属。作为一项规则，非金属都是热的不良导体电（石墨碳是个例外）和热；他们是脆的，往往是强烈的色彩，并显示一个非常广泛的熔点和沸点。其分子结构，通常涉及一般共价键，从简单的双原子分子氢，氯，碘，和氮气的大分子的金刚石，硅和硼。Thenonmetalsthataregasesatroomtemperaturearethelow-molecularweightdiatomicmoleculesandthenoblegasesthatexertverysmallintermolecularforces.Asthemolecularweightincreases,weencounteraliquid(Br2)andasolid(I2)whosevaporpressuresalsoindicatesmallintermolecularforces.CertainpropertiesofafewnonmetalsarelistedinTable2非金属，在室温下是气体的分子量和双原子分子的惰性气体，施加很小的分子间力。随着分子量增大，我们遇到一个液体（溴）和固体（碘）的蒸气压力也表明小分子间力。某些性能的几个非列于表2SimplediatomicmoleculesarenotformedbytheheaviermembersofGroupsVandVIatordinaryconditions.Thisisindirectcontrasttothefirstmembersofthesegroups,N2andO2.Thedifferencearisesbecauseofthelowerstabilityofπbondsformedfromporbitalsofthethirdandhighermainenergylevelsasopposedtothesecondmainenergylevel2.Thelargeratomicradiiandmoredenseelectroncloudsofelementsofthethirdperiodandhigherdonotallowgoodparalleloverlapofporbitalsnecessaryforastrongπbond.Thisisageneralphenomenon—strongπbondsareformedonlybetweenelementsofthesecondperiod.Thus,elementalnitrogenandoxygenformstablemoleculeswithbothσandπbonds,butothermembersoftheirgroupsformmorestablestructuresbasedonσbondsonlyatordinaryconditions.Note3thatGroupVIIelementsformdiatomicmolecules,butπbondsarenotrequiredforsaturationofvalence.简单的双原子分子没有形成较重的群体成员的第五和第六在普通条件。这是在直接对比的第一个成员的这些群体，氮气和氧气。差异是因为较低的稳定的π债券形成轨道的第三个及以上的主要能量水平相对于第二主要能源。较大的原子半径和更密集的电子云的第三周期元素和较高的不允许平行重叠的轨道需要一个强大的π债券。这是一个普遍现象的π债券形成的唯一的元素之间的二期。因此，氮元素和氧形成稳定的分子与σ和π债券，但其他成员的团体形成更稳定的结构的基础上σ债券只在普通条件。注3，第七族元素形成双原子分子，但π债券不需要饱和价。Sulfurexhibitsallotropicforms.Solidsulfurexistsintwocrystallineformsandinanamorphousform.Rhombicsulfurisobtainedbycrystallizationfromasuitablesolution,suchasCS2,anditmeltsat112°C.Monoclinicsulfurisformedbycoolingmeltedsulfuranditmeltsat119°C.BothformsofcrystallinesulfurmeltintoS-gamma,whichiscomposedofS8molecules.TheS8moleculesarepuckeredringsandsurviveheatingtoabout160°C.Above160°C,theS8ringsbreakopen,andsomeofthesefragmentscombinewitheachothertoformahighlyviscousmixtureofirregularlyshapedcoils.Atarangeofhighertemperaturestheliquidsulfurbecomessoviscousthatitwillnotpourfromitscontainer.Thecoloralsochangesfromstrawyellowatsulfur'smeltingpointtoadeepreddish-brownasitbecomesmoreviscous.硫展品同素异形体。固硫存在2晶体形式和非晶态形式。正交硫是通过结晶从一个合适的解决方案，如二硫化碳，它融化在112摄氏°单斜硫是由冷却熔化的硫和它融化在119°C两种形式的结晶硫磺熔化成s-gamma，由8分子。级分子折叠环和生存加热至约160°C.160以上°，级环打开，其中一些片段相互结合，形成高粘度混合物的不规则形线圈。在一系列的温度较高的液体硫成为粘性，它不会从容器。颜色的变化也从稻草黄色硫的熔点为深褐色因为它变得更加粘稠。As4theboilingpointof444°Cisapproached,thelarge-coiledmoleculesofsulfurarepartiallydegradedandtheliquidsulfurdecreasesinviscosity.Ifthehotliquidsulfurisquenchedbypouringitintocoldwater,theamorphousformofsulfurisproduced.Thestructureofamorphoussulfurconsistsoflarge-coiledheliceswitheightsulfuratomstoeachturnofthehelix;theoverallnatureofamorphoussulfurisdescribedas3rubberybecauseitstretchesmuchlikeordinaryrubber.Inafewhourstheamorphoussulfurrevertstosmallrhombiccrystalsanditsrubberypropertydisappears.4沸点444℃°接近，large-coiled分子的硫部分退化和液体的粘度降低。如果把热的液体硫到入冷水中淬火，产生无定形硫。无定形硫的结构由八个硫原子的large-coiled螺旋与螺旋的每一圈；整体性描述一个无定形硫橡胶因为它像普通橡胶。在几个小时无定形硫还原为小菱形晶体和它的弹性也会消失。Sulfur,animportantrawmaterialinindustrialchemistry,occursasthefreeelement,asSO2involcanicregions,asH2Sinmineralwaters,andinavarietyofsulfideoressuchasironpyriteFeS2,zincblendeZnS,galenaPbSandsuch,andincommonformationsofgypsumCaSO4•2H2O,anhydriteCaSO4,andbarytesBaSO4•2H2O.Sulfur,inoneformoranother,isusedinlargequantitiesformakingsulfuricacid,fertilizers,insecticides,andpaper.硫，一个重要的原材料工业化学，是自由的元素，如二氧化硫在火山地区，如硫化氢矿泉水，并在各种硫化矿如铁黄铁矿，闪锌矿，方铅矿等，并在共同形成石膏CaSO4•2H2O，硬石膏CaSO4，和重晶石BaSO•2H2O。硫，一种或另一种形式，被大量用于制造硫酸，化肥，杀虫剂，和纸。SulfurintheformofSO2obtainedintheroastingofsulfideoresisrecoveredandconvertedtosulfuricacid,althoughinpreviousyearsmuchofthisSO2wasdiscardedthroughexceptionallytallsmokestacks.Fortunately,itisnoweconomicallyfavorabletorecoverthesegases,thusgreatlyreducingthistypeofatmosphericpollution.Atypicalroastingreactioninvolvesthechange:硫的形式，二氧化硫在焙烧硫化矿回收和转化为硫酸，虽然以前这种二氧化硫被丢弃通过高大的烟囱。幸运的是，现在是经济上有利的回收这些气体，从而大大减少这种类型的大气污染。一个典型的焙烧反应涉及改变：Phosphorus,below800℃consistsoftetratomicmolecules,P4.Itsmolecularstructureprovidesforacovalenceofthree,asmaybeexpectedfromthethreeunpairedpelectronsinitsatomicstructure,andeachatomisattachedtothreeothers6.Insteadofastrictlyorthogonalorientation,withthethreebonds90°toeachother,thebondanglesareonly60°.Thissupposedlystrainedstructureisstabilizedbythemutualinteractionofthefouratoms(eachatomisbondedtotheotherthree),butitischemicallythemostactiveformofphosphorus.Thisformofphosphorus,thewh