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Question
It has been observed that first ionization energy of 5 d series of transition elements are higher than that of 3d and 4d series, explain why?
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Solution
The transition elements of 5d series have intervening 4f orbitals. There is greater effective nuclear charge acting on outer valence electrons due to the weak shielding by 4f electrons. Hence first ionisation energy of 5d series of transition elements are higher than that of 3d and 4d series.
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