# What is the formula for calcium sulfate?

$C a S {O}_{4}$
Calcium is a Group 2 metal; it tends to lose 2 electrons upon oxidation to form the $C {a}^{2 +}$ ion. Sulfate ion has a formula of $S {O}_{4}^{2 -}$. Formation of the binary salt, $C a S {O}_{4}$, is thus electrically and chemically reasonable.