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Complete 9th Class Chemistry Notes | Class Notes for All Grades

Complete 9th Class Chemistry Notes



Learn in this chapter you will about:

  • What is chemistry, its definition and importance?
  • Land mark in the history of chemistry.
  • Chemistry and society
  • Branches of chemistry.
  • The scientific approach in chemistry.

1.1  WHAT IS CHEMISTRY (Definition and its Importance)

People of the industrialized nations have a higher standard of living than the human race has ever known. More nutritious food, better health, better life and much more of this is due to chemistry. Chemistry enables us to design all sorts of materials, drugs to fight disease, pesticides to protect our health and fertilizers to grow our crops for abundant food, fuels for transportation, fibers to provide comfort and variety in clothes and a lot of other things.

Chemistry also helps us to understand the nature of our environment and about ourselves. The theories of chemistry illuminate o-understanding of the material world from tiny atom to giant galaxies.


Chemistry is the branch of science that deals with the properties, composition and structure of matter. Chemistry also deals with the changes involved in the matter. It also deals with the principles governing the changes which matter may undergo.