What are the important features of valence bond theory?

Explanation

(i) When half filled orbitals of two atoms overlap, a covalent bond will be formed between them.
(ii) The resultant overlapping orbitals are occupied by the two electrons with opposite spins.
For example when `H_(2)` is formed, the two 1s electron of two hydrogen atoms get paired up and occupy the overlapped orbitals.
(iii) The strength of a covalent bond depends upon the extent of overlap of atomic orbitals. Greater the overlap, larger is the energy released and stronger will be the bond formed.
(iv) Each atomic orbital has a specific direction (except s-orbital which is spherical) and hence orbital overlap takes place in the direction that maximises overlap.
(v) Depending upon the nature of overlap, the bonds are classified as `sigma` covalent bond and `pi` covalent bond.
(vi) When two atomic orbitals overlap linearly along the axis, the resultant bond is called a sigma `(sigma)` bond. This overlap Is also called "head-on-overlap" or "axial overlap"
(vii) When two atomic orbitals overlap Sideways the resultant covalent bond is called a `(pi)` bond.