When nitrogen and aluminum form an ionic bond, the formula of the ionic compound is AlN.
Aluminum forms a cation Al⁺³ and nitrogen forms an anion N⁻³. When each cation of Al⁺³ combines with an anion of N⁻³, AlN or aluminum nitride is formed. In AlN a strong electrostatic force of attraction exists between the oppositely charged Al⁺³ and N⁻³ ions.
Any substance that accept a proton by definition is considered to be BRONSTED LOWRY BASE. Bronsted Lowry defined acid and base on the basis of donating or accepting protons. In the Bronsted Lowry classification of acid and base, an acid is defined as a substance which donate proton while a base is defined as a substance which accept proton.