Question

The Formula of a compound of Radium is ${\mathrm{RaBr}}_2$. Write the formula of Radium Carbonate.

Answer 1

The Given Compound of Radium is ${\mathrm{RaBr}}_2$
We know, that the oxidation state of Halogens (Group 17 in periodic table) is always -1.

The Oxidation state of Radium (Ra) in ${\mathrm{RaBr}}_2$ is +2 as the Oxidation state of Bromine(Br) is -1

Chemical formula of Carbonate ion is ${\left({\mathrm{CO}}_3\right)}^{2-}$

Hence, Oxidation state of Carbonate ion is -2

The Compound Formed Must be neutral.

That is the net charge of the compound must be zero.

Hence, in order to neutralize the compound one atom of Radium Require one Carbonate ion

Thus, The Formula of the compound is ${\mathrm{RaCO}}_3$