Here's why:

* Ca: Represents Calcium, an alkaline earth metal.

* ClO₂: Represents the hypochlorite ion.

* 2: Indicates that there are two hypochlorite ions (ClO₂) per calcium ion (Ca).

Important Note: The formula is often written as Ca(ClO₂)₂ to clearly show the two hypochlorite ions are bound to the calcium ion.

Calcium hypochlorite is a powerful oxidizing agent and is commonly used as a disinfectant and bleaching agent.