The positive ion Mg is Magnesium (Mg²⁺) and the negative ion Cl is Chloride (Cl⁻).

When they combine, they form Magnesium Chloride (MgCl₂).

Here's why:

* Magnesium (Mg) loses two electrons to become a positively charged ion (Mg²⁺).

* Chlorine (Cl) gains one electron to become a negatively charged ion (Cl⁻).

* To balance the charges, you need two chloride ions (2 x -1 = -2) for every one magnesium ion (+2).