# What is the formula for aluminum nitrite?

The formula for aluminum nitrite is $\text{Al(NO"_2)_3}$.
Aluminum nitrite consists of the aluminum cation $\text{Al"^(3+)}$ and the polyatomic nitrite anion $\text{NO"_2^(-)}$. Since an ionic compound must be neutral, the number of each ion must result in an overall charge of zero.
Since the aluminum ion has a charge of 3+, and the nitrite ion has a charge of 1-, there need to be three nitrite ions for every aluminum ion. Therefore, the chemical formula for aluminum nitrite is $\text{Al(NO"_2)_3}$.