Which formula corresponds to calcium hydride?

Calcium hydride is a compound formed from calcium and hydrogen. In this compound, each calcium atom, which has a +2 charge as an alkaline earth metal, pairs with two hydrogen atoms to achieve stability. The formula CaH2 accurately represents this 1:2 ratio of calcium ions to hydride ions.

The calcium ion (Ca²⁺) balances with two hydride ions (H⁻), which brings a total of two negative charges from hydrogen to offset the positive charge from calcium. This leads to a neutral overall charge for the compound, aligning with the principles of chemical bonding and stability.

Other formulas listed do not reflect the correct stoichiometry of calcium and hydrogen in this compound. While CaH denotes one calcium with one hydrogen, Ca2H2 improperly suggests a different ionic balance. Similarly, CaH3 would imply a higher hydrogen ratio that does not correspond to the known structure of calcium hydride. This understanding of ionic charges and ratios is crucial in identifying the proper formula for calcium hydride as CaH2.