Calcium bromide is an ionic compound that is made from calcium element which is a alkaline earth metal and bromine element which is a non metal in group 7.
Calcium is in group 2 and has a valency of 2 which means it looses two electrons to form a stable configuration, while bromine has a valency of 1 which means it requires to gain one electron to form a stable configuration.
Therefore, a compound Calcium Bromide, with a formula CaBr₂, contains one calcium atom and 2 bromide atoms. Thus, the ratio of metal ions to non-metal ions is 1:2.