Ions and crystals

Sodium chloride and similar compounds existed a molecule in liquid form, but as arrays of ions in solid form. This geometric regularity was maintained by interactions of electromagnetic forces.
 William Henry Bragg and William Lawrence Bragg England 1914 Ions and crystals

Sodium chloride and similar compounds existed a molecule in liquid form, but as arrays of ions in solid form. This geometric regularity was maintained by interactions of electromagnetic forces.