Explain the formation of CaF_2.

Atomic Number of Ca is 20.

Electronic Configuration of Ca : 2, 8, 8, 2

 

When Calcium loses two electrons, it becomes Ca²⁺ and attains stable electronic arrangement of argon.

Now,            

Ca → Ca²⁺   + 2e^- 

Atomic Number of F = 9

Electronic Configuration of F : 2, 7

 

Fluorine on gaining one electron forms an anion F^- and attains stable electronic arrangement of neon.

                                     F + e^- → F^-

The oppositely charged ions are held together by strong electrostatic forces of attraction as shown :-