Classification of crystalline solids

Crystalline solids can be further classified depending on the nature of the bonding as:

• Ionic

• Molecular

• Covalent

• Metallic

Classification of Crystalline solids

Types of Solids	Constituent Particles	Nature of forces	Examples
Ionic	Positive and negative ions	Strong electrostatic forces of attraction	KCl, BaSO4 KNO3, LF
Molecular	Molecules	(I) Vander Waal’s forces (ii) Dipole interaction (iii) Hydrogen bonding	I2, CO2(solid) HCl Ice
Covalent	Atom	Covalent bonds	Diamond, silicon
Metallic	Positive metal ions (kernels) and mobile electrons	Metallic bonds	All metals and some alloys

Some substances adopt different structural arrangements under different conditions. Such arrangements are called Polymorphs.

Example: Diamond and graphite are two different polymorphic forms of carbon.