Carbon dioxide (CO2\text{CO}_2CO2) is a gas at room temperature, whereas silicon dioxide (SiO2\text{SiO}_2SiO2) is a crystalline solid with a very high melting point of 1713 ∘C1713\ ^\circ\text{C}1713 ∘C.
Which statement correctly accounts for this extreme difference in physical properties?
Silicon-oxygen bonds are ionic with strong electrostatic forces, whereas carbon-oxygen bonds are covalent with weak intermolecular attractions.
Carbon dioxide consists of simple molecules held together by weak intermolecular forces, whereas silicon dioxide is a giant covalent structure with a continuous network of strong covalent bonds.
The double covalent bonds in CO2\text{CO}_2CO2 are weaker than the single covalent bonds in SiO2\text{SiO}_2SiO2, meaning less thermal energy is required to break them during sublimation.
Silicon dioxide exists as a giant metallic lattice with delocalised electrons, whereas carbon dioxide forms a molecular lattice held together by weak electrostatic forces between ions.
74 exam-style questions on OCR GCSE Chemistry Bonding. Each one has a worked solution and a mark scheme showing where the marks go.