Final answer:
Aluminum, a group 3A metal, commonly forms an Al³⁺ ion after losing its three valence electrons to achieve a stable electron configuration.
Step-by-step explanation:
The ion typically formed by aluminum, a group 3A metal, is the aluminum cation with a charge of 3+: Al³⁺. Aluminum has three valence electrons in its outer shell, as indicated by its electron configuration 3s²3p¹. When these electrons are lost, aluminum achieves a stable noble gas electron configuration and forms the Al³⁺ ion.
The rule for determining the charge of ions for elements in groups 13-17 is to subtract 10 from the group number, explaining why aluminum from group 13 forms a 3+ ion.