Question

In Calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion $\left(C{a}^{2+}\right)$ and fluoride ion $\left(F^{-}\right)$ are

• A. 8 and 4
• B. 4 and 8
• C. 4 and 2
• D. 6 and 6

Answer 1

The correct option is A 8 and 4

The fluorite structure, seen in calcium fluoride, has the calcium ions in a face centered cubic array with the fluoride ions in all (8) of the tetrahedral holes. The fluoride ions have a coordination number of 4, and the calcium ions have a coordination number of 8.