Question

What is the Formal charge on $\mathrm{Cl}$ in ${\mathrm{HClO}}_4$?

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. The formula of formal charge

The 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. The formal charge on $\mathrm{Cl}$ in ${\mathrm{HClO}}_4$

• The formal charge on $\mathrm{Cl}$=$7-0-\frac{1}{2}\left(14\right)=0$

So, the formal charge on $\mathrm{Cl}$ in ${\mathrm{HClO}}_4$ is zero.