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How do you account for the following: (i) all scandium salts are white ? (ii) the first ionisation enthalpies of 5d transition elements are higher than those of the 3d and 4d transition elements in respective groups ? |
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Answer» Solution :(i) In scandium salts, scandium has +3 OXIDATION state, `Sc^(3+)` does not have unpaired ELECTRONS and THEREFORE there is no d-d transition. Hence its salts are white. (ii) DUE to poor SHIELDING effect of 5d and 4f- electrons, the effective nuclear charge increases. Hence ionisation enthalpy of 5d transition elements is more than that of 3d and 4d-elements in respective groups. |
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