Form giant ionic structures - see previous page
High melting points - Large amount of energy needed to overcome strong attractive force between oppositely charged ions
Do not conduct electricity in their solid forms - Ions are held in fixed positions in lattice so movement of charge is not possible
Conduct electricity when they are molten or dissolved in water - Lattice breaks down and ions can move freely
Brittle - If a stress is applied to the crystal, the ion layers move slightly, bringing like charges in contact with each other. These repel each other, causing the crystal to fracture.