# How many fluorine atoms bond with calcium to form calcium fluoride?

The formula of calcium fluoride is $C a {F}_{2}$.
Calcium, a Group 2 metal, commonly forms a $C {a}^{2 +}$ ion. On the other hand, fluorine, a Group 7 non-metal, commonly forms an ${F}^{-}$ ion. The necessity of electrical neutrality ensures that $2 \times {F}^{-}$ binds to one $C {a}^{2 +}$.
Note that the structure of the mineral, fluorite, affords very high physical constants as it is a very stable structure. $L {i}_{2} O$ is called $\text{antfluorite}$. Why?