Ionic compounds have regular structures, called giant ionic lattices. In a giant ionic lattice, there are strong electrostatic forces of attraction acting in all directions between the oppositely charged ions. The structure and bonding of ionic compounds explain their properties.
Energy must be transferred to a substance to make it melt or boil. This energy overcomes the strong electrostatic forces of attraction which act in all directions between the oppositely charged ions:
The more energy needed, the higher the melting point or boiling point. Since the electrostatic forces of attraction between oppositely charged ions are strong, their melting and boiling points are high.
|Compound||Melting point||Boiling point|
You can see from the data in the table that sodium chloride is a solid below 801°C, a liquid between 801°C and 1413°C, and a gas at temperatures higher than 1413°C.
A substance can conduct electricity if:
An ionic compound can conduct electricity when:
Both these processes allow ions to move from place to place. Ionic compounds cannot conduct electricity in the solid state because their ions are held in fixed positions and cannot move.