Explain in terms of structure why giant ionic lattices have high melting and boiling points. [4]

Giant ionic lattices are regular structures, held together by ionic bonds. These ionic bonds are strong electrostatic forces of attraction between oppositely charged ions, acting in all directions. Energy is required to break these ionic bonds when the substance melts or boils. Since a giant ionic lattice contains a large number of ions and hence a large number of ionic bonds, it takes a lot of energy to break these strong electrostatic forces of attraction between the oppositely charged ions. As a result, an ionic compound will have a high melting or boiling point.