10年地化课件（复习）

AppliedGeochemistryDaiTagenSchoolofGeosciencesandEnvironmentalEngineeringCentralSouthUniversityPartOneGeochemicalTheory1.Somebasicconcepts1.1AtomsAtomsarethebasicparticlesengagedinchemicalreactions.Theinnerstructuresoftheatomsarethemaindeterminantsofthechemicalandphysicalcharacteristicsofmaterials.Asatinnyparticle,theradiusofanatomisonlyabout10-10m.Theradiusofthenuclearofanatomisevenfarsmaller,10-14~10-15m.Thatmeansanatomisnearlyempty.Atomsconsistofanucleus（核）ofprotons（N）andneutrons（Z）surroundedbyelectrons.Astheatomicnumberincreases,thenumberofnucleuscharges(1unitnucleuscharge=1.60*10-19C)increasesaswell.Theprotons,neutronsandelectronsofanatommakeupanelectromagneticsystem.Anucleusispositivelycharged,butthesurroundedelectronsarenegativelycharged.Thatiswhythewholeatomiselectricallyneutral.Nuclearstabilityarerelatedto(1)theparityofthenumberofprotons(Z)andthatofneutrons(seealsoChapter2).(2)theratioofthenumberofneutronstothatofprotons.N/Z.N/Zofnucleusofelementwithitsatomicnumbersmallthan20isroughlyequalto1.Itmeansthatsuchanuclearismoststablebecauseinthiscasethebindingenergyinsidethenuclearisinitsultimateextent.ElectronicStructureofAtomsElectronsofatomcircumvolvearounditsnucleusinhighspeeds.Becausetheelectrons’movementhasnofixedorbits,electronicclouds（电子云）areformedintheouterofthenucleus.Theheavyareaofelectronicclouds—anareawhereelectronsappearmostfrequently—iscalledelectronicshell.1.2THEELEMENTSGeochemistry(地球化学):Geochemistrydealswiththeabundance（丰度）anddistribution（分配）oftheelements。Abundance（丰度）：Thecontentofanelementinanygeologicalmass(orbody).Distribution（分配）：Thelocalcontentofanelementinageologicalbody(mass).Theabundanceanddistributionoftheelementsdependontheirphysicalandchemicalproperties.Intrue,thesepropertiesdependontheelectronicstructureoftheatomsandvarysystematicallywiththenuclearcharge(atomicnumber).(1)AbundanceoftheelementsOnegoalofgeochemistryisthedeterminationoftheabundanceoftheelementsinnature.Thisinformationisneededtodevelophypotheses（假说）fortheoriginoftheelementsandofthestructureoftheuniverse.Thesehypothesesareonlyasgoodasthechemicaldataandassumptionsonwhichtheyarebased.Thesedataareobtainedinmanydifferentways,andthequalityandquantityoftheresultsvaryfordifferentmaterialsandfromelementtoelement.A.AbundanceoftheelementsintheUniverseTheuniverseismadeupmainlyofstars,nebulae(星云),andinterstellargas(星际气体)anddust.Ourknowledgeoftheabundanceoftheelementsintheuniversecomesfromtwomajorsources:A.Spectroscopicanalyses（光普分析）ofthelightfromstarsandnebulae,particularlyforvolatile(挥发elements).B.Meteorites陨石(fornonvolatileelements).Meteoriteanalysesarenotasabundantowingtoalimitednumberofsamples.Table1-1Atomicabundancesoftheelements(relativetosilicon=106atoms)AtomicnumberElementCosmicChondrites球粒陨石）EarthEarth’scrust1H3.18×1010-8.4001.4×1052He2.21×1090.113.5×10-5-3Li49.5~50-2904Be0.810.69-315B3506.2-936C1.18×1072.0007.0001,7007N3.74×10690201408O2.15×1073.7×1063.5×1062.9×1069F2.450~7003003,30010Ne3.44×1060.001512×10-5-11Na6.0×1044.6×1044.6×1041.0×10512Mg1.061×1069.4×1058.9×1059.6×10413Al8.5×1046×1049.4×1043.0×10514Si1.00×1061.00×1061.00×1061.00×10615P9.6005.3001×1043,40016S5.0×1051.1×1051×10581017Cl5.7007003.20037018Ar1.172×1050.45.9×10-2-19K4.2003.5004,0005.3×10420Ca7.21×1044.9×1043.3×1041×10521Sc3529-4922Ti2.775~2.6002,0001.2×10423V262200-26024Cr1.27×1046.6008.00019025Mn9.3007.4004.0001,70026Fe8.3×1056.9×1051.35×1061×10527Co2.2101.3003.5004228Ni4.80×1044×1041×10513029Cu540250-8730Zn1.244130-11031Ga4812-2232Ge11520-2.133As6.64.6-2.434Se67.29-0.06335Br13.55-3.136Kr46.8-0.6×10-5-37Rb5.88~5-11038Sr26.920-43039Y4.83.4-3740Zr28~37-18041Nb1.41.0-2242Mo4.02.5-1.644Ru1.91.5--45Rh0.40.25--46Pd1.3~0.9--47Ag0.45~0.09-0.06548Cd1.480.079-0.1849In0.1890.001-0.08750Sn3.60.56-1.751Sb0.3160.11-0.1652Te6.420.60--53I1.090.051-0.3954Xe5.380.7×10-5-0.7×10-5-55Cs0.3870.140.142.356Ba4.85.05.031057Ka0.4450.390.392258Ce1.181.21.24359Or0.1490.140.145.860Bd0.780.640.641962Sm0.2260.230.234.063Eu0.0850.0820.0820.7964Gd0.2970.340.343.465Tb0.0550.0510.0510.5766Dy0.360.330.331.867Ho0.0790.0760.0760.7368Er0.2250.230.231.769Tm0.0340.0310.0310.2870Yb0.2160.180.181.771Lu0.0360.0310.0310.2972Hf0.210.170.171.773Ta0.0210.0160.0161.174W0.160.120.120.8275Re0.0530.0460.046-76Os0.750.540.54-77Ir0.7170.350.35-78Pt1.41.301.30-79Au0.2020.180.180.00280Hg0.40.100.100.0481Tl0.1920.0010.0010.2282Pb40.140.146.083Bi0.1430.0020.0020.0890Th0.0580.0270.0274.192U0.02620.0090.0091.1B.RegularitiesanddifferencesoftheabundanceoftheelementsWhentherelativeabundancesofTable1-1areplottedagainstatomicnumber(Fig.1-1).Certainregularitiesanddifferencesareobserved.Anyattempttoexplaintheoriginoftheelementsmustexplainthefollowing.a.Theextremeabundanceofhydrogenandhelium(morethan99percentbyweightofallatoms).b.Thegeneraldecreaseinabundancewithincreasingatomicnumber.c.Therelativelylowabundanceofsomeelements(suchaslithium,Beryllium,Boronandscandium)andtherelativelyhighabundanceofotherelements(suchasiron.nickel,andlead).d.Thegreaterabundanceofevenatomicnumberelementsascomparedtooddatomicnumbereleme