Question

Explain why CO2 is a gas while SiO2 is a solid at room temperature.

Answer 1

Only very weak dispersion intermolecular forces hold the molecules together and CO2 is a gas at room temperature. SiO2 is a network covalent solid. Each silicon makes four bonds by making four Si-O single bonds. The covalent network leads to a very strongly bonded solid with a very high melting point.