What is the chemical formula for calcium hydride?

The chemical formula for calcium hydride is represented as CaH2. This indicates that each calcium atom bonds with two hydrogen atoms to form the compound. Calcium, being an alkaline earth metal, typically has a +2 charge in ionic compounds. In contrast, hydrogen, when it acts as a hydride, carries a -1 charge.

To achieve electrical neutrality in calcium hydride, one calcium ion (Ca²⁺) pairs with two hydride ions (H⁻). Therefore, the formula must reflect the correct stoichiometry required to balance these charges, which is captured appropriately in CaH2.

Other options do not accurately express the correct ratio of calcium to hydrogen atoms. For instance, CaH would suggest only one hydrogen atom, and it does not balance the +2 charge from calcium. Ca2H would imply that there are two calcium atoms and only one hydrogen atom, disrupting the balance necessary for the compound. Ca2H3 indicates an incorrect ratio, as it would imply two calcium atoms combined with three hydride ions, leading to an incorrect net charge. Thus, CaH2 is the valid and correctly balanced formula for calcium hydride.