Final answer:
When aluminum reacts with nitrogen, it forms an ionic compound called aluminum nitride (AlN).
Step-by-step explanation:
When aluminum reacts with nitrogen, it forms an ionic compound called aluminum nitride (AlN). This compound is formed by the transfer of electrons from aluminum to nitrogen, resulting in aluminum cations (Al³+) and nitride anions (N³¯). Since it is a compound between two elements, it is considered a binary compound.