# What is the total number of electrons in the valence shell of an atom of aluminum in the ground state?

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{1}$
The first two electrons fill the first shell. Another eight electrons fill the second shell. This is a total of ten electrons in filled shells. That leaves 3 electrons in the third shell. This is the valance shell since it is not filled. So the $3 {s}^{2} 3 {p}^{1}$ electrons are the valance electrons for a total of 3 valance electrons.