Write the energy level diagram of oxygen molecule.

Explanation

Atomic number of oxygen =8. Electronic configuration of oxygen `=1s^(2)2s^(2)2p^(4)`. When two oxygen atoms combines, the molecular orbital energy level diagram is as shown in the figure. From the diagram, the molecular electronic configuration of oxygen is
`sigma_(1s^(2)),sigma_(1s^(2))^(***),sigma_(2s^(2))^(***),sigma_(2p_(2)^(2)),{pi_(2p_(x))^(2)=pi_(2p_(y))^(2)}`
`{pi_(2p_(x)^(1))^(***)=pi_(2p_(y)^(1))^(***)}`
Bond order `=("no. of BMO"e^(-)-"no. of"ABMOe(-))/2`
`=(N_(be)-N_(abe))/2`

Here BMO electrons `sigma_(1s)^(2),sigma_(2s^(2)),sigma_(2p_(x)^(2)),{pi_(2p_(x)^(2)=pi_(2p_(y)^(2))}` i.e. `N_(be)=10`
ABMO electrons `sigma_(1s^(2))^(***),sigma_(2s^(2))^(***),sigma_(2p_(x)^(1))^(***){pi_(2p_(x)^(1))^(***)=pi_(2p_(y)^(1))^(***)}`, i.e. `N_(abe)=6`
`BO=(10-6)/2=4/2=2` i.e. between oxygen there exists double bond.
Magnetic property: Therefore are two unpaired electrons `{pi_(2p_(x)^(1))^(***)=pi_(2p_(y)^(1))^(***)}` therefore, oxygen molecule is paramagnetic in nature.