* Sodium (Na) has a +1 charge (Na⁺) as it's in group 1 of the periodic table.
* Nitrogen (N) has a -3 charge (N³⁻) as it's in group 15 of the periodic table.
To create a neutral compound, we need three sodium ions (3 x +1 = +3) to balance the negative charge of one nitride ion (-3).
