Here's how we determine this:

* Ionic Compounds: These compounds are formed by the electrostatic attraction between oppositely charged ions.

* Calcium (Ca): Calcium is a metal in group 2 of the periodic table. It forms a +2 ion (Ca²⁺) when it loses two electrons.

* Chlorine (Cl): Chlorine is a nonmetal in group 17 of the periodic table. It forms a -1 ion (Cl⁻) when it gains one electron.

To form a neutral compound, we need to balance the charges. Two chloride ions (2 Cl⁻) with a total charge of -2 will balance the +2 charge of one calcium ion (Ca²⁺).