Question

What is the formal charge of $\mathrm{CO}$?

Answer 1

Step1. Formal charge

• The formal charge of an atom in a polyatomic molecule or ion may be defined as the difference between the number of valence electrons of that atom in an isolated or free state and the number of electrons assigned to that atom in the Lewis structure.

Step2. Formula of formal charge

Formal charge (F.C.) on an atom in a Lewis structure=

$\left[\text{total number of valence electrons in the free atom —}\text{total number of non bonding (lone pair) electrons — (1/2) total number of bonding(shared) electrons}\right]$Step3. Formal charge of $\mathrm{CO}$

• Total number of valence electrons on carbon is four.
• Total number of valence electrons on oxygen is six
• Formal charge on carbon=$4-2-\frac{1}{2}\left(6\right)==-1$
• Formal charge on oxygen=$6-2-\frac{1}{2}\left(6\right)=+1$
• So, the net formal charge of $\mathrm{CO}$ is zero.

So, the formal charge of $\mathrm{CO}$ is zero.