Sodium Chloride is an alkali halide with an fcc crystal structure. The basis is two ions, a sodium cation and a chlorine anion. The crystal lattice parameter is 0.563 nm. The diagram shows both a unit ...

Structure is a giant ionic lattice. It has a high melting point because a large amount of energy is needed to break the strong ionic bonds between the magnesium and chloride ions in the lattice.