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

Explanation

E.C. of `._(4) Be = 1s^(2) 2s^(2)`
M.O.E.C. of ` Be_(2) = sigma _(1s)^(2) sigma_(1s)^(2) sigma_(2s)^(2) sigma_(2s)^(2)`
`therefore ` Bond order = `(1)/(2) (4-4) = 0 `. Hence , `Be_(2)` does not exist .