Here's why:

* Cations are positively charged ions.

* Anions are negatively charged ions.

* Ionic compounds are formed by the electrostatic attraction between cations and anions.

In CaCl₂:

* Ca (calcium) is a metal and tends to lose electrons to form a positive ion, Ca²⁺.

* Cl (chlorine) is a nonmetal and tends to gain electrons to form a negative ion, Cl⁻.

The formula CaCl₂ indicates that there are two chloride ions (Cl⁻) for every one calcium ion (Ca²⁺) to balance the charges.