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
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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
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These solids can be further be into four categories the basis of the nature of intermolecular forces acting over them