The electron configuration for magnesium is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^2$. What is the distribution of electrons in the electron shells of a magnesium atom?

Distribution of electrons in the electron shells of a Magnesium atom:

• The number of electrons in the magnesium atom is 12 electrons, for which the electron configuration of magnesium is given as:

$\mathrm{Mg}(\mathrm{Z}=12)=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^2$

• The first two electrons have been placed in the $1\mathrm{s}$orbital, which can accommodate two electrons.
• The further two electrons of magnesium go next in the $2\mathrm{s}$ orbital.
• The next six electrons will go into the $2\mathrm{p}$ orbital which can hold up to six electrons.
• Then we can put the remaining two electrons in the $3\mathrm{s}$ subshell.
• Hence, the distribution of electrons in the electron shells for the magnesium atom is given as : $2,8,2$

Thus, the distribution of electrons in the electron shells for the magnesium atom is given as : $2,8,2$.