why does calcium fluoride have a higher melting point than flourine?!?

Answer 1

Calcium fluoride (CaF2) is an insoluble ionic compound of calcium and fluorine. Strong charge-charge electric atraction exists between every pair of closely located Ca and F ions, hence the melting point must be very high. On the other hand, F2 is a non-polar molecule. Only week Van Der Waals interaction between the molecules. Hence the melting point of F2 is very low.