1. Take a small amount of sodium chloride (NaCl) on a metal spatula (having an insulated handle).
2. Heat it directly over the flame of a burner.
3. We will see that sodium chloride (NaCl) does not melt easily.
4. Sodium chloride melts (and becomes a liquid) only on strong heating.
5. This shows that sodium chloride which is an ionic compound possesses strong bonds.
6. So it has a high melting point.
7. Whereas covalent compound like naphthalene and carbon tetra chloride has low boiling points such as 80° C and 77° C respectively.
8. The force of attraction between the molecules of a covalent compound is very weak.
9. Only a small amount of heat energy is required to break these weak molecular forces, due to which covalent compound has low melting points and low boiling points.
