Question
Explain CO2 is a gas while SiO2 is solid.
Solution
CO2 is gas. It exists as discrete, monomeric linear gaseous molecule and remains as a gas at room temperature due to the following reasons.
(i) Due to small atomic size, carbon atom possesses partial triple bond character with neighbouring oxygen atoms.
(ii) Due to a linear structure, carbon dioxide molecule is non-polar and thus CO2molecules exhibit weak Vander Waal’s forces.
Silica is solid. In its molecule, each silicon is covalently bonded to four oxygen atoms, which are disposed of tetrahedrally around it and each oxygen atom is linked to two silicon atoms. Thus, silica exists as a network solid (giant molecule) having a three-dimensional structure.
