Magnesium reacts with an element $\left(\mathrm{X}\right)$ to form an ionic compound. If the ground state electronic configuration of $\left(\mathrm{X}\right)$ is $1{\mathrm{s}}^2\mathrm{ }, 2{\mathrm{s}}^2, \mathrm{ }2{\mathrm{p}}^3$, the simplest formula for this compound is

Magnesium ion $={\mathrm{Mg}}^{+2}$

The electron configuration of an element describes how electrons are distributed in its atomic orbitals. Electron configurations of atoms follow a standard notation in which all electron-containing atomic subshells (with the number of electrons they hold written in superscript) are placed in a sequence.