# Which one of the following is the ground-state electron configuration of the Mg2+ ion?

Apr 4, 2015

Magnesium is located in period 3, group 2 of the periodic table, and has an atomic number equal to 12. This means that a neutral magnesium atom has 12 electrons that surround its nucleus.

When magnesium loses two of its electrons, it becomes the $M {g}^{2 +}$ cation, which implies that the total number of electrons will decrease by 2.

As a result, the electron configuration of the $M {g}^{2 +}$ cation must account for a total of 10 electrons.

${\text{Mg}}^{2 +} : 1 {s}^{2} 2 {s}^{2} 2 {p}^{6}$

The $M {g}^{2 +}$ cation is isoelectronic with neon, $N e$, and has a noble gas shorthand notation of

"Mg"^(2+):["Ne"]