Question

In CaF2 the co-ordination no of cation and anion are ? A-:8,6 B-:4,4 C-:8,4 D-:6,6 and plz explain the answer.

Answer 1

In CaF2, the coordination number of cation and anion are 8:4. As there are twice as many F- ions as there are Ca+2ions, therefore the coordination number of both the ions is different. Each Ca+2ion is surrounded by eight F- ions, giving a body centered cubic type of arrangement and each F- ion is tetrahedrally surrounded by four Ca+2ions. The calcium Flouride structure is also known as the flourite structure.