Question

Considering x-axis as the internuclear axis which out of the following will not form a sigma bond and why? (a) Is and Is (b) Is and 2px ; (c) 2py and 2py (d) 1s and 2s.

Answer 1

A sigma bond is formed by axial overlapping of atomic orbital. It is always formed between two half filled atomic orbitals along their internuclear axis i.e the line joining the centers of the nuclei of two atoms. 2p_y, and 2p_y will not form sigma bond because they can only undergo sidewise overlapping of atomic orbitals and form pi bond.