Answer:
The answer to your question is Mg loses its valence electrons and acquire a positive charge (Mg⁺²).
Explanation:
Valence electrons are important for an element to attach to another one, metals lose these electrons while nonmetals gain electrons to complete the octet rule.
Magnesium is a metal that loses these electrons so when it becomes an ion Magnesium will have a positive charge Mg⁺².