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Illustrate bytakingexamplesof transitionelements andnon- transition elementthat oxidationstatesof elementare largelybasedon electronicconfiguration . |
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Answer» Solution :Oxidation state of an elementis the charge(+ veor - ve)with an atomof theelementhas on its ion orappears to havewhenpresentin thecombinedstatewith otheratoms.The actualsign and exactvalue ofoxidationstate onan elementhoweverdependsuponits electronicconfiguration. For non-transition (representationelement ), the VALUE of theoxidationstate is equalto the numberof electronspresent intheoutermostshellor eightminus thenumber of electrons present in theoutermost shells(valenceshell ) . Forexamples- blockelementhave eitherone (alkali metals ) ortwo (alkalineearthmetals)electrons in theoutermost shellwhich theycan loseveryeasilyto acquirethe stableelectronicconfigurationof the nearestnoblegas and hence show oxidationstatesof either+ 1( alkalimetals ) or + 2(alkalineearthmetals).p-Blockelements on theother handshowpositivenegativeand evenzerooxidationstates. Forexampleacquiregroup 13 ELEMENT(i.e.,B , A1 ETC ) . have three electrons in theoutermost shellwhichthey canloseeasily toacquirestableelectronicconfiguration of the nearestnoblegas andhenceshowa maximumoxidationstateof + 3 . Elementsof group 14(i.e.,C, Si )neither haveastrongtendencyto lose or gain fourelectrons andhenceshowa maximu oxidationstate of+ 4or minimumof -4 group15 elements (i.e.,N, P , etc ) have a somewhatmore tendencyto gainthreeelectron than tofive electronsand henceshow a minimumoxidationstate of-3 ormaximumof + 5. Group16elements(i.e.,O, S, etc )haveeven moretendency togain twoelectrons than tolose six electrons and hence showa minimu oxidation state of -2 or maximumof +6Group 17elements(i.e.,halogens , F, C1 etc ) have thehighesttendency to gainone thanoflosesevenelectronsand henceshow aminimumoxidationstate of-1 ormaximumof + 7 . The storyof group18 elements (i.e.,noblegases ) is however quite different . Theyhave theirrespective valenceshells complete(Hehas two , all other have eightelectrons) and henceshow notendecyto loseor gainelectrons. Thereforein general , they showan oxidationstateof zero. forexamplehelium, neonand argondo not at allenterinto chemicalcombination andhence alwaysshow an oxidationstate ofzero . Howeverthere aresomeexceptions . Forexamplekryptonshowssometendencytoenter intochemicalcombinationand shows amaximum oxidationstatesof + 8 sinceit haseightelectrons in thevalenceshell. Likesome p- blockelements, transitionelements( d- block) andinnertransitionelement(f - block )alsoshowvariableoxidationstates. But unlikep- blockelements, the variableoxidationstates of transitionandinnertransitionelements arisedue toinvolvement ofnot onlyhte valenceelectronsbut d-or f-electronsaswell. However theirmostcommonoxidationstatesare + 2and + 3. |
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