Final answer:
Aluminum phosphide is an ionic compound formed by the transfer of electrons from aluminum to phosphorus, resulting in a compound consisting of Al^3+ and P^3- ions.
Step-by-step explanation:
Aluminum phosphide is considered an ionic compound. This is because aluminum, a group 13 element, tends to use all its valence electrons when it reacts, resulting in compounds where aluminum typically has an oxidation state of 3+. Phosphorus, being a nonmetal, reacts with metals like aluminum to form binary compounds. Given that aluminum can form ionic compounds with nonmetals, it would react with phosphorus to form aluminum phosphide (AlP) featuring Al3+ and P3- ions. The ionic nature of aluminum phosphide is distinguished by the transfer of electrons from aluminum to phosphorus, creating a compound that is electrically neutral yet composed of ions.