Question

In calcium fluoride structure, the coordination numbers of calcium and fluoride ions are:

• A. $8$ and $4$
• B. $6$ and $8$
• C. $4$ and $4$
• D. $4$ and $8$

Answer 1

Answer: (A)

$8$ and $4$

The $C{a}^{2+}$ and $F^{-}$ are located in $Ca{F}_2$ crystal respectively at face-centred cubic lattice points and in tetrahedral voids. The calcium fluoride structure is also called fluorite structure. It is 8:4 arrangement, the coordination number of $C{a}^{2+}$ and $F^{-}$ ions is 8 and 4 ions respectively.