Question

In the vapour state, alkali metals may exist as atoms or diatomic molecules. If sodium forms a diatomic molecule, what will be its bond order ?

Answer 1

Sodium (all alkali metals for that matter) has one valance electron in ${}^{\prime }{S}^{\prime }$ orbital.

$Na\to {1S}^2{2S}^2{2p}^6{3S}^1$

$\therefore$ If it forms a bond in vapor state with another sodium atom, the two's electrons will form a pair, i.e., only one pair of electrons will be shared indicating a single covalent bond. Thus, Bond order $=1$.