# How do you calculate the number of valence electrons in a molecule?

Aug 4, 2017

To calculate the number of valence electrons in a molecule you would observe the periodic table to show you the valence of each element in the molecule to calculate the overall number.

#### Explanation:

An example of a molecule for which you may need to find the number of valence electrons may be CO (carbon monoxide).

Looking at the periodic table, you will find C is in $\text{group}$ $4$ and so has $4$ valence electrons.

Looking at the periodic table, you will find O is in $\text{group}$ $6$ and so has $6$ valence electrons.

So the total number of valence electrons in the CO molecule is $4 + 6 = 10$.

This video describes valence electron numbers in molecules:

This video describes valence electron numbers in elements:

More complicated molecules will need analysis using the Lewis dot structure, which is introduced here: