Covalent Bonds are the bonds which are formed by sharing of electrons.
· When sharing of one pair of electron takes place is known as single covalent bond.
· When sharing of two pair of electrons takes place is known as double bond.
· When sharing of three pair of electron takes place is known as triple bond.
Formal Charge (F.C.)
For polyatomic molecule or ion, formal charge of an atom in a Lewis structure = [Total no. of Valence electron in free Atom] - [total no. of non bonding (lone- pair) elements]- 1/2[total no of bonding (shared) electrons]
Ex :- Lewis structure of O3 (ozone molecule)