# Difference between PI bond and Sigma bond

Sigma bond : “$\sigma$ – bond is along the internuclear axis. It has a cylindrical symmetry.”

Pi Bond : “A covalent bond formed by a sidewise overlap of ‘p’ orbitals of atoms that are already bonded through a  $\sigma$ – bond, and in which the electron clouds are present above and below the internuclear axis is known as π – bond”.

### Difference between Sigma bond and Pi bond

Sigma bond ($\sigma$) Pi bond ($\pi$)
This is formed due to the overlap of pure s – s; s – p ; p – p (or) hybrid orbitals of two atoms along their internuclear axis. This bond is formed due to lateral or sidewise or parallel overlapping of pure ‘p’ orbitals of two atoms.
It is a strong bond. It is a weak bond.
These are less reactive. These are highly reactive.
The electron cloud is symmetrical to the line joining the nuclei of the two atoms. The electron cloud lies above and below the plane of the line joining the atoms.
Free rotation of atoms is possible. Free rotation is not possible.
The lobe participating in the overlapping is stretched and the other lobe is reduced. Both the lobes take part in bonding and remain the same in size.
It is also called localised bond. It is non-localised bond.
It has independent existence. It forms only after the formation of ‘$\sigma$‘ bonds.