The electron configuration of 22 X^2+ ion is

The electron configuration of 22 X^2+ ion is 

A. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2

B. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^1 

C. 1s^2 2s^2 2p^6 3s^2 3p^6

D. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 

The correct electron configuration of the

${}^{22}{\text{X}}^{2+}$

ion is D.

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^2$

The neutral atom with atomic number 22 (Titanium, Ti) has 22 electrons with the configuration

${\text{1s}}^2{\text{2s}}^2{\text{2p}}^6{\text{3s}}^2{\text{3p}}^6{\text{4s}}^2{\text{3d}}^2$

. When forming a positive ion, electrons are removed first from the orbital with the highest principal quantum number, which is the

$\text{4s}$

orbital. To form a

$\text{+2}$

ion (

${\text{X}}^{2+}$

), both electrons from the

$\text{4s}$

orbital are removed, resulting in the configuration

${\text{1s}}^2{\text{2s}}^2{\text{2p}}^6{\text{3s}}^2{\text{3p}}^6{\text{3d}}^2$

. 

---