Classification of solids based on different …

Crystalline solids can be classified into different categories depending upon the type of constituent particles and the nature of attractive forces operating between them.

Atomic Solid: In these solids the constituent particles are atoms. These closely packed atoms are held up by London dispersion forces. Some examples are crystals of noble gases. Such solids are very soft, possess very low melting points and poor conductors of heat and electricity.
Molecular Solids: In these solids, the constituent particles which pack up together are molecules of the substance. These molecules may be non – polar (dipole moment = 0) such as etc. or they may be polar (dipole moment > 0) like etc.  

Ionic Solids: In ionic solids, the constituent particles are ions of opposite charges. Each ion is surrounded by a definite number of ions of opposite charge.
Covalent Solids: In these types of solids the constituent particles are atoms of same or different elements connected to each other by covalent bond network.

Metallic Solids: In these type of solids, the constituent particles are metal atoms. The interparticle forces in these solids are metallic bonds. In the metallic crystals the metal atoms occupy the fixed positions but their valence electrons are mobile.