Covalent compounds have the following properties for the following reasons:
- low melting points --> have weak intermolecular bonds and their only strong covalent bonds are between the atoms. Therefore less energy is needed to overcome the forces of attraction so less heat is needed to melt them
- poor conductors of electricity when dissolved in water and otherwise --> the molecules are all neutral overall so there are no charged particles able to carry an electric current
Ionic compounds have the following properties for the following reasons:
- high melting and boiling points --> ionic compounds are giant structures and have a strong electrostatic force so high temperatures (lots of energy) is needed to break them
- conduct electricity when molten or dissolved in water --> ions that carry the current are free to move in a liquid state
- brittle --> ionic compounds are structured as an ionic lattice
Ionic lattices are made up of alternating positive and negative ions. When ions with the same charge come into contact with one another they repel each other and the ionic lattice breaks/shatters.