Question

Two p orbitals can overlap to form a σ molecular orbital. How many nodes are present in this

σ molecular orbital?

Is there no node or two nodes? Please explain.

Answer 1

Solution:

Two p orbitals can combine contructively or destructively. In constructive situation you have a lower energy bonding orbital. If they align destructively you have the higher energy antibonding orbital. In a σ bond, the orbital will appear cylindrically symmetric. In such cases the atoms at the end of the bonds can rotate without breaking the bond. This is the case from the bonds between the s orbitals in hydrogen. P orbitals can overlap in two different ways. If they overlap head-on a σ bond is formed.

The corresponding antibonding, or σ* orbital, is defined by the presence of one nodal plane between the two bonded atoms.