Question

Electronic configurations of `Cu ( Z = 29)` is
A. `[Ar] 3d^(9) 4 s^(2)`
B. `[Ar] 3d^(5) 4 s^(2)`
C. `[Ar] 3d^(10) 4 s^(1)`
D. `[Ar] 3d^(6) 4 s^(2)`

Answer 1

Correct Answer - C
The expected electronic configuration of `Cu (29)` is `[Ar] 3 d^(9) 4s^(2)` but actually it is found to be `[Ar] 3 d^(10) 4 s^(1)`. This is because fully filled `d` orbitals are more stable than incompletely filled d-orbitals are more stabe than incompletely filled d-orbits to `3d` orbital to give a more stable configuration.