Question

How are bonding and antibonding orbitals different?

Answer 1

Clearly, bonding orbitals promote bonding. More specifically, they promote higher electron densities, meaning high orbital occupation probabilities. Antibonding orbitals promote electronic nodes or nodal planes, meaning low orbital occupation probabilities.

For example:

`1s ("bonding") + 1s ("antibonding") = sigma_(1s)^"*"`, which has a node in between the lobes.

`1s ("bonding") + 1s ("bonding") = sigma_(1s)`, which has greater electron density overall.