The electronic configurations of chromium (at. no. 24 ) and copper (at. no. 29 ) are

Question

The electronic configurations of chromium (at. no. 24 ) and copper (at. no. 29 ) are (A) [ Ar ] 4 s 1 3 d 5 and [ Ar ] 4 s 1 3 d 10 (B) [ Ar ] 4 s 2 3 d 4 and [ Ar ] 4 s 1 3 d 10 (C) [ Ar ] 4 s 1 3 d 5 and [ Ar ] 4 s 2 3 d 9 (D) [ Ar ] 4 s 2 3 d 4 and [ Ar ] 4 s 2 3 d 9

Tardigrade Admin · Accepted Answer

Chromium and copper have five and ten electrons in 3 d-orbitals rather than four and nine because fully-filled and half-filled orbitals have lower energy and thus have extra stability. Therefore, chromium and copper have d5 and d10-configurations.

Q. The electronic configurations of chromium (at. no. $24$ ) and copper (at. no. $29$ ) are

$[A r] 4 s^{1} 3 d^{5}$ and $[A r] 4 s^{1} 3 d^{10}$

$[A r] 4 s^{2} 3 d^{4}$ and $[A r] 4 s^{1} 3 d^{10}$

$[A r] 4 s^{1} 3 d^{5}$ and $[A r] 4 s^{2} 3 d^{9}$

$[A r] 4 s^{2} 3 d^{4}$ and $[A r] 4 s^{2} 3 d^{9}$

Chromium and copper have five and ten electrons in $3 d$ -orbitals rather than four and nine because fully-filled and half-filled orbitals have lower energy and thus have extra stability. Therefore, chromium and copper have $d^{5}$ and $d^{10}$ -configurations.

Q. The electronic configurations of chromium (at. no. 24 ) and copper (at. no. 29 ) are

[Ar]4s13d5 and [Ar]4s13d10

[Ar]4s23d4 and [Ar]4s13d10

[Ar]4s13d5 and [Ar]4s23d9

[Ar]4s23d4 and [Ar]4s23d9