1The relative strength of a sigma bond is related to the extent of overlap of the atomic orbitals. This is known as the 'principle of maximum overlap'.
Due to spherical charge distribution in s-orbital, generally s-s overlapping is not so effective as s-p and p-p overlapping.
Where p-orbitals have directional charge distribution and longer lobes which cause more effective overlapping. Thus s-s sigma bond is relatively weak.
Order of the strength of sigma bonds is as follows:
nature of sigma bond bond strength
s-s 1.0
s-p 1.73
p-p 3.0
cn clearly detect d order from here.
