Answer:
They lose two electrons.
Explanation:
When an atom loses are gain the electrons ions are formed.
There are two types of ions.
Anion
Cation
1 = Anion
It is formed when an atom gain the electrons. when atom gain electron negative charge is created on atom. For example.
X + e⁻ → X⁻
2= Cation
It is formed when an atom loses the electrons. when atom lose electron positive charge is created on atom. For example.
X → X⁺ + e⁻
There are two valance electrons in group two elements. They loses two electron to complete the octet and form cation with a charge of +2.
For example:
Mg → Mg⁺² + 2e⁻
