# How does each column of the periodic table relate to electron configuration?

Feb 6, 2017

$\text{For main group elements, the column, the Group number}$$\text{........represents the number of valence electrons.}$
Hydrogen is in $\text{Group I}$, and has the one valence electron. Chlorine is in $\text{Group VII}$, and has SEVEN valence electrons.
The $\text{Group number}$ also represents the maximum oxidation number that the element can attain. To take chlorine again, this element can exhibit a $+ V I I$ oxidation state, i.e. in $C l {O}_{4}^{-}$, and cannot be further oxidized.