MO Configuration ($$\le 14$$electrons, e.g.,$$\text{N}_2$$)

Energy Order: $$\sigma_{1s} < \sigma^*_{1s} < \sigma_{2s} < \sigma^*_{2s} < (\pi_{2p_x} = \pi_{2p_y}) < \sigma_{2p_z} < (\pi^*_{2p_x} = \pi^*_{2p_y}) < \sigma^*_{2p_z}$$

Concept: Represents the increasing energy sequence of molecular orbitals for lighter homonuclear diatomic molecules where $$\text{s-p}$$ mixing significantly alters the relative placement of the $$\sigma_{2p_z}$$ orbital.

Notation:

• $$\sigma, \pi$$ = Bonding molecular orbitals;
• $$\sigma^*, \pi^*$$ = Antibonding molecular orbitals;
• $$x, y, z$$ = Spatial orientations of the constituent atomic $$p$$-orbitals.