Question

In CaF₂ , how are the cations surrounded by anions?

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+2 ions, therefore the coordination number of both the ions is different. Each Ca+2 ion is surrounded by eight F- ions, giving a body centered cubic type of arrangement and each F- ion is tetrahedrally surrounded by four Ca+2 ions. The calcium Flouride structure is also known as the flourite structure.