* Magnesium (Mg): Magnesium is a metal with a +2 charge.
* Periodate (IO₄⁻): Periodate is a polyatomic ion with a -1 charge.
* Balancing Charges: To balance the charges, we need two periodate ions (2 x -1 = -2) to match the +2 charge of the magnesium ion.
Therefore, the correct formula is Mg(IO₄)₂.
