How is orbital overlap maximum condition important for JEE exam calculations?

The concept of delocalization or resonance can be explained for quantum mechanical atomic models in which electrons are considered to be spread over the entire molecular orbital.

The fundamental assumption of the valence bond theory contradicts the delocalization. The valence bond theory assumes that

The central atom of nitrogen has 5 valence electrons as per the electronic configuraion. During the formation of ${\mathrm{N}\mathrm{H}}_3$ , 3 valence electrons forms three sigma bonds with hydrogen and one lone electron pair is left.

• The steric number  of the ammonia molecule: SN=3 bonds +1 lone pair $=4$ t