Question

what is hybridisation ?

Answer 1

Hybridization is the idea that atomic orbitals fuse to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. Hybridization is also an expansion of the valence bond theory.

Answer 2

Hybridization happens when atomic orbitals mix to form a new atomic orbital. The new orbital can hold the same total number of electrons as the old ones. The properties and energy of the new, hybridized orbital are an 'average' of the original unhybridized orbitals.

The concept of hybridization was introduced because it was the best explanation for the fact that all the C - H bonds in molecules like methane are identical.