Give energy level diagram obtained by over lapping of $2{{\rm{p}}_{\rm{z}}}$ orbitals.And give a diagram of the orbits of that composition.

By $LCAO$, $2 p_{z}^{1}-2 p_{z}^{1}$ are overleap and form $MO$. The energy diagram is under.

Where, $\mathrm{AO}=$ Atomic orbitals $\left(\right.$ here, $\left.2 p_{z}\right)$

$\mathrm{MO}=$ Molecular orbitals (here, $\sigma 2 p_{z^{\prime}} \sigma^{*} 2 p_{z}$ )

$\mathrm{BMO}=$ Bonding orbitals (here, $\sigma 2 p_{z}$ )

$\mathrm{ABMO}=$ Antibonding orbitals (here $\sigma^{*} 2 p_{z}$ )

Energy : $\left(2 p_{z}^{1}+2 p_{z}^{1}\right)=\left(\sigma 2 p_{z}+\sigma^{*} 2 p_{z}\right)$

Energy order : $\sigma 2 p_{z}<2 p_{z}^{1}<\sigma^{*} 2 p_{z}$

The axia figure of $MO$, $\sigma^{*} 2 p_{z}$ and $\sigma 2 p_{z}$ are formed by $LCAO$ of two atom $2 p_{z}^{1}$ are as under figure.

$\text { Where, } \psi_{2 p_{x}}+\psi_{2 p_{x}} \frac{\text { Positive }}{\text { Overlapping }} \psi_{\text {MO }}=\pi 2 p_{x}$

$\psi_{2 p_{x}}-\psi_{2 p_{x}} \frac{\text { Opposite }}{\text { Overlapping }} \psi_{\text {ABMO }}=\pi^{*} 2 p_{x}$

In $\pi$ type $BMO$ $(+)$ and $(-)$ waves are below and above of internuclear axis and electron density between two nucleus.

In $\pi^{*}$ type ABMO vertical nodal is located. Electron density is not between two nucleus. $(+)$ and $(-)$ waves are below and above the internuclear axis.