but im wondering why in Molecular Orbital diagram the Antib

Solution

To clear your confusion I am giving you one explanation related to H2 molecule....

the hydrogen molecule,H2. We will use the two 1s atomic orbitals (one on each H atom) to “build” molecular orbitals for the H2 molecule. Whenever two atomic orbitals overlap, twomolecular orbitals form. Thus, the overlap of the 1s orbitals of two hydrogen atoms to form H2 produces two MOs. One of the molecular orbitals lies lower in energy from the two atomic orbitals from which it was made; the other molecular orbital lies higher in energy.

The lower-energy MO of H2 concentrates electron density between the two hydrogen nuclei and is called the bonding molecular orbital. This sausageshaped MO results from summing the two atomic orbitals so that the atomic orbital wave functions combine in the region between the two nuclei. Because an electron in this MO is attracted to both nuclei, the electron is more stable (it has lower energy) than it is in the 1s atomic orbital of an isolated hydrogen atom.
Further, because this bonding MO concentrates electron density between the nuclei, it holds the atoms together in a covalent bond. The higher-energy MO has very little electron density between the nuclei and is called the antibonding molecular orbital. Instead of combining in the region between the nuclei, the atomic orbital wave functions cancel each other in this region, leaving the greatest electron density on opposite sides of the nuclei. Thus, this MO excludes electrons from the very region in which a bond must be formed. An electron in this MO is repelled from the bonding region and is therefore less stable (it has higher energy) than it is in the 1s atomic orbital of a hydrogen atom.

Now in the final the constructive interference of wave function makes the probability of finding of particle maximum, as the quantum mechanics says the wave funcrion is totally about probabilty not about energy. Thats why electron try to stay in bonding orbital instead in antibonding orbital.

:)