Using molecular orbital theory, determine the bond order and magnetic property of $O_2$.

Total electrons in $O_2$ = 16. MO configuration:

$$(\sigma_{1s})^2(\sigma^*_{1s})^2(\sigma_{2s})^2(\sigma^*_{2s})^2(\sigma_{2p})^2(\pi_{2p})^4(\pi^*_{2p})^2$$

$$Bond Order = \frac{N_b - N_a}{2} = \frac{10 - 6}{2} = 2$$

The two electrons in $\pi^*_{2p}$ orbitals are unpaired (by Hund's rule):

$$O_2 is paramagnetic$$