Why is the charge on an aluminium ion 3+

The charge of an aluminum ion is typically 3+. This is because the element's atomic number is 13, reflecting the fact that it has 13 electrons and 13 protons. The valence shell of aluminum has three electrons, and per the octet rule, these three electrons are lost resulting in just 10 electrons and 13 protons.

Perimeter? wheres the answers

Must be negative.substance increases