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Question
Use Hund’s rule to derive the electronic configuration of Ce3+ ion and calculate its magnetic moment on the basis of ‘spin-only’ formula.
Solution
The electronic configuration of Ce and Ce3+ ions is as follows:
Ce (Z = 58): 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f1 5s2 5p6 5d1 6s2
or, [Xe] 4f1 5d1 6s2
Ce3+ (Z = 55): [Xe] 4f1
Thus Ce3+ has only one unpaired electron, i.e. n = 1
∴ μs = `sqrt("n"("n" + 2))` BM
= `sqrt(1 xx (1 + 2))` BM
= `sqrt3` BM
= 1.732 BM
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