Draw and explain the M.O. diagram of lithium molecule.

Explanation

(i) Electronic configuration of Li atom: `1s^(2)" "2s^(1)`
(ii) Electronic configuration of `Li_(2)` molecule is `sigma 1s^(2)" "1s^(2)" "sigmas^(2)`
(iii) Bond order `=N_(b) - N_(a) //2=4- 2//2`
(iv) `Li_(2)` molecule has no unpaired electrons, hence it is diamagnetic.