State the crystal structures of SiO2 and CO2 and why one has a higher melting point than the other.
SiO2 forms a giant covalent structure while CO2 has a simple molecular structure.In the giant covalent structure of SiO2, strong covalent bonds hold the atoms together in the structure, while CO2 has only weak intermolecular forces or dipole-dipole forces between molecules to hold the molecules together. The covalent bonds of SiO2 are much stronger than weak intermolecular forces of CO2 and so take more energy to be broken, therefore the melting point of SiO2 is much higher than that of CO2 .
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