Tamil Nadu Board of Secondary EducationHSC Science Class 11

Classification of Matter



  1. Pure Substances: Elements and Compounds
  2. Mixture: Homogeneous and Heterogeneous mixture


Classification of Matter:-
Based on the chemical composition of various substances.


  • It is the simplest form of the matter. 
  • The smallest unit of an element is known as an atom.
  • The total number of known elements is 118 out of which 98 elements occur naturally and 20 are formed by artificial transmutation.
  • Examples: Na, K, Mg. Al, Si, P, C, F, Br etc.


  • It is a non-elemental pure compound.
  • Formed by a chemical combination of two or more atoms of different elements in a fixed ratio.
  • Examples: H2O, CO2, C6H12O6 etc.


  • Formed by the physical combination of two or more pure substances in any ratio.
  • The chemical identity of the pure components remains maintained in mixtures.
  • Homogeneous mixtures are those whose composition for each part remains constant.
  • For example, Aqueous and gaseous solutions.
  • Heterogeneous mixtures are those whose composition may vary for each and every part. For example, Soil and concrete mixtures.
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