# How can I count valence electrons?

Apr 17, 2014

The valence electrons are the electrons that determine the most typical bonding patterns for an element.

These electrons are found in the s and p orbitals of the highest energy level for the element.

Sodium $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{1}$
Sodium has 1 valence electron from the 3s orbital

Phosphorus $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{3}$
Phosphorus has 5 valence electrons 2 from the 3s and 3 from the 3p

Iron $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2} 3 {d}^{6}$
Iron has 2 valence electrons from the 4s

Bromine $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2} 3 {d}^{10} 4 {p}^{5}$
Bromine has 7 valence electrons 2 from the 4s and 5 from the 4p
you can count the electrons in the out most shell