Question

Sif6 2- is stable where as sicl6 2- not

Answer 1

In Silicon tetra flouride

The Si atom is very small and cannot hold the larger 6 cl- ions

The bonding between Si and Cl is very low stability

Answer 2

Explanation:

In silicon hexachloride, the silicon atom is surrounded by six chlorine atoms and it is known that the size of chlorine atom is larger than fluorine atom. Therefore, due to large size of chlorine atoms there occurs repulsion between chlorine atoms.

As a result, silicon hexachloride becomes unstable.

Whereas in silicon hexafluoride, the silicon atom is surrounded by six fluorine atoms. It is known that size of fluorine is smaller than chlorine atom so, there are less repulsion between fluorine atoms.

Hence, silicon hexafluoride is more stable than silicon hexachloride.