Ionic Compounds all have high melting points and high boiling points. This is because they have strong electrostatic forces between the ions and so it requires a large amount of energy to overcome this.
When ionic compounds are free to move, (when they are melted), they carry an electrical current. Ionic compounds dissolve easily in water. The ions seperate and are all free to move in the solution, so they will carry electric current.
Substances with covalent bonds can be simple molecules (molecules made up of only a few atoms). All simple molecules have a low meling and boiling point, are gases or liquids at room temperature, and they dont conduct electricity.
In molecular substances, atoms form very strong covalent bonds to make small molecules of several atoms. By contrast, the intermolecular forces are very weak. This gives them a low boiling and melting point as little energy is needed to overcome those bonds.
Giant covalent strucutres (macromolecules) dont contuct electricity, even when molten and a lot of energy is need to overcome…