Ionic compounds usually have the following physical properties:

High melting temperatures → Giant lattice network of ions → Large attractive electrostatic force → Large amount of energy required to overcome this force

Brittleness →Applying a stress causes layers to slide over each other → Ions of same charge now side by side → Strong repulsive force causes crystals to break apart

Poor electrical conductivity when solid, but good when molten → Solid ionic compounds have no delocalised electrons and cations are not free to move → Molten ionic compounds have mobile ions which can migrate to charged electrode

Often soluble in water →Energy required to break lattice apart can be supplied by hydration of separate ions → Water can attract positive and negative ions because of its polarity → Conduct electricity when dissolved in water