What is lewis structure of SiO2?
Instead SiO2 is the basic formula unit of a tetraedrical tertiary structure. Each Si-atom covalently binds four oxygen atoms with a single bond. A more accurate formula would be SiO4/2. Each oxygen binds two Si-atoms, so that a crystal stucture is formed. This network is very strong wherefore the melting point is way higher than CO2. This is why SiO2(/4) produces sand while CO2 is rather hard to make solid.
