Why are pi (#pi#) bonds weaker than sigma (#sigma#) bonds?

1 Answer
Feb 27, 2014

Pi bonds are weaker than sigma bonds because the side-on overlap of p orbitals is less effective than end-on overlap.


In a σ bond, the electrons are in orbitals between the nuclei of the bonding atoms.

Electron density is greatest between the nuclei.

The electrons attract the nuclei and form a σ bond — the strongest type of covalent bond.


In a π bond, the p orbitals overlap side-on.

The overlap is less efficient, because the electron density is off to the sides of the σ bond.

The electrons are not as effective in attracting the two nuclei. Thus, a π bond is weaker than a σ bond.