Question

What is the formula of `"magnesium nitride"`, `Mg_3N_2`?

Answer 1

Consider the typical valencies of magnesium metal and dinitrogen in their compounds.

Explanation:

Magnesium is a Group 2 metal with 2 valence electrons that can be oxidized:

`Mg rarr Mg^(2+) + 2e^-`

Dinitrogen is a gaseous non-metal that can be reduced to `N^(3-)`: Each nitrogen ATOM has 5 valence electrons, and this configuration can be reduced to `N^(3-)`.

`1/2N_2(g) + 3e^(-)rarrN^(3-)`

Since typically non-metals can oxidize metals, or metals reduce non-metals, we cross multiply to give the stoichiometric equation:

`3Mg(s) + N_2(g) rarr Mg_3N_2(s)`

Such a reaction is called a nitriding reaction. It would require conditions of high temperature.