Question

Carbon and silicon belong to (IV) group. The maximum coordination number of carbon in commonly occurring compounds is 4, whereas that of silicon is 6. This is due to

• A. availability of low lying d-orbitals in silicon
• B. large size of silicon
• C. more electropositive nature of silicon
• D. both (b) and (c)

Answer 1

The correct option is A availability of low lying d-orbitals in silicon

$C:2s^{2}2p^2$
$Si:3s^{2}3p^2$
Carbon has no d-orbital to expand but Si has vacant d-orbitals and it can expand its valency using these vacand d-orbitals and forms 6 coordinated compounds.