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Discuss the generalcharacteristicof the 3dseriesof thetransitionelementswith specialreference to their (i)Atomicsize (ii)Enthalpies of atomisation |
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Answer» SOLUTION :(i) Atomicsize : The atomicsize in 3dtransitionseriesdecrease from Sc to Mnand then`Fe , CO, Ni` have almostsameatomicsize while copperhas bigersize. It isbacausenumberof unpairedelectronsin d- orbitalsincreasesin thebeginingtillMn. Thereforeeffectivenuclearchargeincreases henceatomicsizedecreasethenpairingof electrons ind- orbitalstakesplace,so the ATOMIC sizeremainsthe sameand finallyit increasedue torepulsionbetweenpairedelectron in d-orbitalswhichleadsto decrease inneffectivenuclearcharge . (ii) THEYHAVE highenthalpyof atomisationdue to strongmetallic bondsadn additionalcovalentbondingdue to thepresenceof unpairedelectronsin d- orbitals |
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