`CO_(2)` is a gas while `SiO_(2)` is a solid. Explain.

Explanation

Carbon because of its small size and higher electronegativity than silicon forms `ppi-ppi` double bonds with O-atoms to form `CO_(2)` molecule. These molecules of `CO_(2)` are held together by weak van der Waals forces of attracts which can be easily overcome by collision of the molecules at room temperature. Consequently, `CO_(2)` is a gas.
Silicon, on the other hand, because of its bigger size and lower eletronegativity than carbon has little tendency to form `ppi-ppi` double bonds with `O`-atoms . Instead, each silicon atom forms four single, covalent bonds with O-atoms which are tetrahedrally arranged around it leading to the formation of a three-dimensional network structure . To break these covalent bonds, a large amount of energy is needed and hence `SiO_(2)` is a high melting solid.