How can bonding orbitals in diatomic oxygen be described?
The bonding orbitals in dioxygen are σ,
Each O atom has the electron configuration [He] 2s² 2px² 2py 2pz.
When two O atoms approach along the z-axis, the atomic orbitals overlap to form molecular orbitals.
1s + 1s → σ(1s) and
2pz + 2pz → σ(2pz) and
2px + 2px → π(2px) and
The order of energies is
In the following diagram, the atomic orbitals of the O atoms are on either side, and the molecular orbitals of the O₂ molecule are in the middle.
We place the valence electrons in the atomic orbitals and the molecular orbitals and get the diagram below.
We write the electron configuration of O₂ as