Valence Electron Energy Level Diagram

The table below depicts static figures of the molecular orbitals that hold valence electrons in the diatomic O2 molecule. Each orbital is either bonding, anti-binding, or non-bonding for this specific molecule. There are 12 valence electrons in this molecule and each picture represents two electrons in that specific orbital unless stated otherwise. The first two of each p orbital have the same energy while the third one differentiates. The reason for this is because there are two pi bonding orbitals along with one sigma bonding orbital. The pi bonds share the same energy while for bonding, the sigma bond has a slightly lower energy. For anti-bonding, sigma usually has a slightly higher energy than the anti-bonding pi orbitals. For the orbitals calculated and shown below, the sigma bonding orbital has a slightly higher energy than the pi bonding orbitals do. The non-bonding orbitals include the 2s orbitals because there is the same amount in the bonding and anti-bonding parts. This means that they do not affect the bonding order of the molecule.