Sodium chloride (NaCl\text{NaCl}NaCl) and silicon dioxide (SiO2\text{SiO}_2SiO2) both have giant structures.
Sodium chloride is an ionic compound.
Silicon dioxide is a giant covalent compound.
The table shows some properties of each substance:
| Sodium chloride | Silicon dioxide |
|---|---|
| Melting point = 801∘C801^\circ\text{C}801∘C | Melting point = 1713∘C1713^\circ\text{C}1713∘C |
| Soluble in water | Insoluble in water |
| Conducts electricity when molten | Does not conduct electricity when molten |
Explain why silicon dioxide has a high melting point.
Suggest why the melting point of silicon dioxide is higher than the melting point of sodium chloride.
State why sodium chloride conducts electricity when molten.
Chlorine (Cl2\text{Cl}_2Cl2) is described as a simple molecular substance.
State why chlorine is a gas at room temperature.
