If the coordination number of Ca^{2+} in CaF_ | vedclass

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(B) In the $CaF_2$ crystal structure (fluorite structure),each $Ca^{2+}$ ion is coordinated by $8$ $F^{-}$ ions,forming a cubic geometry.Since the sto

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$4$

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(B) In the $CaF_2$ crystal structure (fluorite structure),each $Ca^{2+}$ ion is coordinated by $8$ $F^{-}$ ions,forming a cubic geometry.Since the stoichiometry of the compound is $1:2$ $(Ca:F)$,the ratio of the coordination numbers must be the inverse of the ratio of the number of ions.Let the coordination number of $Ca^{2+}$ be $CN(Ca^{2+}) = 8$ and the coordination number of $F^{-}$ be $CN(F^{-})$.According to the relation $N_{Ca} 	imes CN(Ca^{2+}) = N_{F} 	imes CN(F^{-})$,where $N$ is the number of ions per unit cell.For $CaF_2$,$1 	imes 8 = 2 	imes CN(F^{-})$.Therefore,$CN(F^{-}) = 4$.

If the coordination number of $Ca^{2+}$ in $CaF_2$ is $8$,then the coordination number of $F^{-}$ ion would be

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