Answer: The charges on cation and anion balances each other.
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
[tex]Mg:12:1s^22s^22p^63s^2[/tex]
[tex]Mg^{2+}:10:1s^22s^22p^6[/tex]
[tex]Cl:17:1s^22s^22p^63s^23p^5[/tex]
[tex]Cl^{-}:18:1s^22s^22p^63s^23p^6[/tex]
Thus [tex]Mg^{2+}[/tex] combines with two [tex]Cl^-[/tex] ions to give neutral [tex]MgCl_2[/tex]
