Chemistry - Introduction


  • Chemistry is a branch of Natural Science that studies about the structure, composition, and changing properties of matters.

  • Chemistry studies the smallest part of a matter i.e. atom (along with its all properties) to the large materials (e.g. gold, silver, iron, etc.) and their properties.

  • Chemistry also studies the intermolecular forces (that provide matter the general properties) and the interactions between substances through the chemical reactions.

  • In 1998, Professor Raymond Chang defined Chemistry as −

    "Chemistry" to mean the study of matter and the changes it undergoes.

  • It is believed that the study of chemistry started with the theory of four elements propounded by Aristotle.

  • The four theory of elements states that “fire, air, earth, and water were the fundamental elements from which everything is formed as combination.”

  • Because of his classical work namely “The Sceptical Chymist,” Robert Boyle, is known as the founding father of chemistry.

  • Boyle formulated a law, became popular as ‘Boyle’s Law.’

  • Boyle’s law is an experimental gas law that analyzes the relationship between the pressure of a gas and volume of the respective container.

  • By advocating his law, Boyle rejected the classical ‘four elements’ theory.

  • The American scientists Linus Pauling and Gilbert N. Lewis collectively propounded the electronic theory of chemical bonds and molecular orbitals.

  • The United Nations declared 2011 as the ‘International Year of Chemistry.’

  • The matter is defined in chemistry as anything that has rest mass and volume and also takes space.

  • The matter is made up of particles.

  • The atom is the fundamental unit of chemistry.

  • The atom consists of a dense core known as the atomic nucleus and it is surrounded by a space known as the electron cloud.

  • The nucleus (of an atom) is composed of protons (+ve charged particles) and neutrons (neutral or uncharged particles); collectively, these two are known as nucleons (as shown in the image given below).

  • A chemical element is a pure form of a substance; it consists of single type of atom.

  • The periodic table is the standardized representation of all the available chemical elements.

  • A compound is a pure form of a substance; it composed of more than one elements.


A molecule is the smallest indivisible part of a pure chemical substance; molecule has distinctive set of chemical properties (see the image given below).

Chemical Properties