Question

Explain why a Sigma $\left(\sigma \right)$- bond is stronger than a Pi$\left(\pi \right)$- bond?

Answer 1

Sigma bonds are formed by head-on the overlap of atomic orbitals. Whereas pi bonds are formed in addition to sigma bonds by sideways overlapping of atomic orbitals. Since the information of a sigma bond, the orbitals are along internuclear axis this results in more effective orbital overlap as compared to when pi bonds are formed as they are perpendicular to the internuclear axis. This significant difference in orbital overlap results in sigma bond being stronger than the pi bond.