Fig. Crystals are crystalline solids
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The constituent particles are arranged in a long range order( symmetry and regularity of arrangement of constituent particles that repeat at any distance from a given atom due to the interaction between the particles) with a regular and periodically repeating pattern over the entire crystal.
o Crystalline solids possess a sharp melting point. o
o
o
Crystalline solids are anisotropic in nature due to different arrangement of particles in different directions. This leads to different value of physical property along different directions in the same crystals.
Metallic elements including iron, copper and silver are typical examples of crystalline solids.
On the other hand non – metallic elements like sulphur, phosphorus and iodine and compounds like sodium chloride, zinc sulphide and naphthalene and quartz are typical examples of crystalline solids.
Fig. Crystalline form of Sodium Chloride
o
These solids can be further be into four categories the basis of the nature of intermolecular forces acting over them