Question

why cr and cu shows abnormal electronic configuration ?​

Answer 1

Explanation:

Copper show abnormal electronic configuration because it is more energy efficient to have a full lower energy orbital than high energy orbital. 4s has higher energy than 3d when it contains electrons i.e. copper with [Ar] 3d^10 4s^1 configuration is in lower energy state than copper with [Ar] 3d^9 4s^1 configuration.

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Answer 2

Copper show abnormal electronic configuration because it is more energy efficient to have a full lower energy orbital than high energy orbital. 4s has higher energy than 3d when it contains electrons i.e. copper with [Ar] 3d^10 4s^1 configuration is in lower energy state than copper with [Ar] 3d^9 4s^1 configuration.