Question

Why does silicone dioxide have a high melting point ?

Answer 1

Answer:

Where SiO2 has strong covalent bonds between molecules, SO3 only has weak van der waals intermolecular forces holding its molecules together. Since covalent bonds require more energy to overcome than van der waals, SiO2 requires a higher temperature than SO3 to melt, thus SiO2 has a higher melting point.