# How do you find the number of valence electrons in an atom?

Apr 22, 2018

Group number or using proton number.

#### Explanation:

Most of the time you can determine the number of valence electrons by the number of the group it is in. For example, $N a$ is in Group $I$ and hence it has one valence electron.

However it is not always conventional as transition metals does not technically have a group number. Thus we use its proton number. Since atoms are nuetrally charged, proton number = electrons in any atom. Thus, we can determine its electron number and write our its configuration. $F e$ has an electronic configuration of [Ar] 3d6 4s2 and thus 2 valence electrons.