Why is equropium (II) more stable than cerium (II) (Eu = 63, Ce =58) give one reason.

Explanation

E.C of Europium (II) is [Xe] `4 f^7 5d^0` and that of cerium (II) is `[Xe] 4f^1 5d^1`. In `Eu^(+2)` , 4f subshell is half filled and 5d subshell is empty. Now half filled and completely filled E.C are extra stable. So `Eu^(2+)` is more stable than `Ce^(2+)` .