Question

Explain the following:

Silicon forms \[\ce{SiF^{2-}6}\] ion whereas corresponding fluoro compound of carbon is not known.

Answer 1

The bond dissociation energy decreases rapidly as the atomic size increases. Since the atomic size of carbon is much smaller (77 pm) as compared to that of silicon (118 pm), therefore, carbon-carbon bond dissociation energy is much higher (348 kJ mol^–1) than that of silicon-silicon bond (297 kJ mol^–1). Hence, because C – C bonds are much stronger as compared to Si-Si bonds, carbon has a much higher tendency for catenation than silicon.