# How do ions form electrically neutral compounds?

Salts are electrically neutral (of course all matter is electrically neutral). If the species contains an anion, there must be cations to balance the charge. It is easy to apportion charges in salts of the halides and the alkali metals, i.e $N a X$. The sodium has a positive charge, which is balanced by a negative halide ion. For alkali metal salts of the Group 16 elements, oxides, and sulfides, etc., the formula would be $N {a}_{2} O$, $L {i}_{2} O$ etc. The point is that for a neutral salt, the cation (or gegenion) must draft in sufficient anions/cation to give electrical neutrality.
Lithium nitride is known. If you know that the nitride anion is ${N}^{3 -}$, how would you formulate its lithium salt?