The ionic compound formed by Na (sodium) and N (nitrogen) is sodium nitride (Na₃N). Here's how to determine the formula:

* Sodium (Na) is in group 1 of the periodic table, meaning it has a +1 charge as a cation (Na⁺).

* Nitrogen (N) is in group 15 of the periodic table, meaning it has a -3 charge as an anion (N³⁻).

To form a neutral compound, we need three sodium ions (3 x +1 = +3) to balance out the charge of one nitrogen ion (-3). This gives us the formula Na₃N.