Use molecular orbital theory to explain why the `Be_(2)` molecules do not exist?

Explanation

`Be(Z=4)rArr 1s^(2)2s^(2)`
The electronic configuration of `Be_(2)` molecule is
`(sigma 1s)^(2)(sigma**1s)^(2)(sigma 2s)^(2)(sigma**2s)^(2)`.
`:. N_(b)=4`,`N_(a)=4`
`BO=1/2(4-4)=0`
Zero bond order of `Be_(2)` shows that it does not exist.