State the reasons for chemical bonding between two atoms and the methods involved for achieving the same. State how 'duplet and octet' rules are involved for an atom to achieve stable electronic configuration.

The reasons for chemical bonding between two atoms is the tendency of elements to acquire the nearest noble gas configuration in their outermost orbit and become stable.

There are three methods in which atoms can achieve a stable configuration :

1. The transfer of one or more electrons from one atom to the other form an electrovalent (or ionic) bond.
2. Sharing of one, two or three pairs of electrons between two atoms to form a covalent (or molecular) bond.
3. When the shared pair of electron pairs are contributed by only one of the combining atoms, the bond formed is known as coordinate (or dative) bond.

For an atom to achieve stable electronic configuration it must have :

Either two electrons in it's outermost shell (nearest noble gas – He) — Duplet rule

Or

Eight electrons in it's outermost shell (all noble gases other than He) — Octet rule.