What are the differences between SIgma bond and Pi - bond?

Sigma Bond

Pi - Bond

1)      A sigma bond is formed by the end to end overlap of half – filled atomic orbitals along the inter – nuclear axis. The overlapping involves two s – orbitals, one s and p – orbital or two p - orbitals

A pi – bond is formed by the sidewise overlap of two half – filled p - orbitals

2)      In this case, the overlapping can take place to a larger extent and therefore, the bond formed is a strong bond

In the formation of Pi - bond the overlapping occurs to a lesser extent and therefore, the bond is weak.

3)      The molecular orbital is symmetrical about the intermolecular axis.

The molecular orbitals is discontinuous and consists of two charged clouds above and below the plane of atoms.

4)      There can be free rotation of atoms around o^- - bond

Because of overlapping of the electrons clouds above and below the plane of the atoms, free rotation of atoms around Pi - bond is not possible.

5)      The bond may be present between two atoms either alone or along with Pi- bond.

The bound is always present between two atoms in addition to sigma bond.

6)      In the formation of sigma bond, s – orbitals can participate.

s – orbitals cannot participate in the formation of pi - bond