# What is the formula for sodium nitride?

Jan 5, 2016

$\text{Na"_3"N}$

#### Explanation:

Sodium is an element in group 1 of the periodic table. As such, it will form an electron by losing a single electron to form a $\text{1+}$ ion: ${\text{Na}}^{+}$.

Nitrogen is an element in group 5 of the periodic table. When it forms the nitride ion, it gains three electrons to form a $\text{3-}$ ion: ${\text{N}}^{3 -}$.

In ionic compounds, the charges of constituent ions must balance. This can be achieved by having three sodium ions per nitride ion. Therefore, the formula of sodium nitride is $\text{Na"_3"N}$.

However, $\text{Na"_3"N}$ is extremely unstable. It rapidly decomposes into its constituent elements according to the equation:

$2 {\text{Na"_3"N" -> 6"Na" + "N}}_{2}$

It lacks a boiling point because of this. Since ionic compounds have very high melting and boiling points as a result of the strong electrostatic attraction between oppositely charged ions that holds them together, sodium nitride should be no different; however, it will decompose as shown at around $360$ Kelvin ($\text{K}$) or $86.85$ $\text{^@ "C}$.