Question

Calculate the formal charge on Cl atom in $HCl{O_4}$

Answer 1

Formal Charge of an atom is basically a concept which can explain the charge assigned to an atom in a molecule, with the assumption that the electrons in all the chemical bonds are shared equally between atoms, irrespective of the relative electronegativity between them.

Complete step by step answer:
The value of formal charge can be calculated using the following formula:
$FC{\text{ }} = {\text{ }}V-N-\dfrac{B}{2}$
Where, V represents the number of valence electrons present in the neutral atom of the compound. N represents the number of non – bonding valence electrons in the same atom. B represents the total number of electrons present in the bonds that the atom under consideration forms with the other atoms in the molecule.
In order to solve this question, we will first need to understand the structure of $HCl{O_4}$:

From this structure, we can determine the values of V = 7; B = 14; N = 0 for the atom of chlorine
Hence, the formal charge on Cl atom in $HCl{O_4}$ $= {\text{ }}7{\text{ }}-{\text{ }}0{\text{ }}-\left( {\dfrac{{14}}{2}} \right){\text{ }} = {\text{ }}0$

Note:
In determining the best Lewis structure (or predominant resonance structure) for a molecule, the structure is chosen such that the formal charge on each of the atoms is as close to zero as possible.