Question on Physical States

Why is CO₂ a gas while SiO₂ is a solid at room temperature?

Answer:

C can form multiple bonds with O as the orbitals used of the lateral overlap are of same size and energy, thus satisfying its valancies by forming 2 s bonds and 2 p bonds with O. Si cannot form such multiple bonds with O as the orbitals overlapping laterally will be of different size and energy. So, Si satisfies all its valancies by forming 4 s bonds with O. This results in CO₂ being monomeric and SiO₂ being polymeric and hence CO₂ is a gas and SiO₂ is a solid at room temperature.