Classification of crystalline solids

Crystalline solids are further classified into four broad categories based on the nature of the constituent particles and the type of force holding them together: ionic solids, covalent network solids, molecular solids and metallic solids. Each category has a distinctive set of physical properties -- melting point, hardness, and electrical and thermal conductivity -- that follows directly from the strength and nature of its interparticle bonding, ranging from the strong, non-directional electrostatic attraction of ionic crystals to the strong, directional covalent bonds of network solids, the weak intermolecular forces of molecular solids, and the delocalised metallic bonding of metals. The following four subsections de …