Final answer:
The formula for an ionic compound composed of barium (Ba) and nitrogen (N) is Ba3N2, resulting from the charge balancing between Ba2+ and N3- using the crisscross method.
Step-by-step explanation:
The formula for an ionic compound made of barium (Ba) and nitrogen (N) involves combining barium cations (Ba2+) with nitrogen anions (N3-). Since barium has a charge of 2+ and nitrogen has a charge of 3-, you need to balance the charges to get a neutral compound. By using the crisscross method, the charges of the ions are switched to become the subscripts of the other ion, leading to Ba3N2. Therefore, the correct formula for the ionic compound made of barium and nitrogen is Ba3N2.