Which of the following options does not represent ground state electronic configuration of an atom?

Options

A. `1s^(2)2s^(2)2p^(2)3s^(2)3p^(6)3d^(8)4s^(2)`
B. `1s^(2)2s^(2)2p^(2)3s^(2)3p^(6)3d^(9)4s^(2)`
C. `1s^(2)2s^(2)2p^(2)3s^(2)3p^(6)3d^(10)4s^(1)`
D. `1s^(2)2s^(2)2p^(2)3s^(2)3p^(6)3d^(5)4s^(1)`

Answer

B

Explanation

Correct configuration should be `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(1)` for the copper which has atomic number `29(""_(29)Cu)`. Due to extra stability of full filled orbital of d-subshell, the last electron enter into d-orbital instead of s-orbital.