How is the binary ionic compound #CaCl_2# named?
Calcium always has an oxidation number of +2. Chlorine when it is reduced by a metal is always -1.
The compound could be named Calcium chloride; some might suggest calcium (II) chloride or even calcium (II) dichloride.
The second and third options provide more explicit information about the compound, but are not recommended because the only possible combination of calcium and chloride is the ratio of 1 calcium cation to 2 chloride anions.