| Period/Timeline | Name of Scientists | Contribution/Invention | Origin of Scientist |
|---|---|---|---|
| 460 - 357 B.C. | Democritus | Proposed the idea of the atom, a Greek indivisible particle of matter. | Greek |
| 428 - 347 B.C. | Plato | Proposed the term 'elements' as the Greek composition of organic and inorganic bodies with a particular shape. | Greek |
| 384 - 322 B.C. | Aristotle | Proposed the idea of a substance as a Greek combination of matter and form. Described theory of the Four Elements, i.e. fire, water, earth, air. | Greek |
| 721 - 803 A.D. | Jabir Ibne-Hayan | Invented experimental methods of Muslim nitric acid, hydrochloric acid and white lead. Extraction of metals from their ores and dyeing clothes. | Muslim |
| 862 - 930 A.D. | Al-Razi | Prepared ethyl alcohol by the fermentation process. | Muslim |
| 973 - 1048 A.D. | Al-Beruni | Determined densities of different substances. | Muslim |
| 980 - 1037 A.D. | Ibn Sina | Contributed to medicine, philosophy and astronomy. | Muslim |
| 1627 - 1691 A.D. | Robert Boyle | Put forward the idea of chemistry as a systematic investigation of nature. Discovered the gaseous law. | English |
| 1728 - 1799 A.D. | J. Black | Discovered carbon dioxide. | Scottish |
| 1731 - 1810 A.D. | Cavendish | Discovered hydrogen. | British |
| 1733 - 1804 A.D. | J. Priestley | Discovered oxygen, sulphur dioxide and hydrogen chloride. | English |
| 1741 - 1820 A.D. | Petit | Determined the classical expression for the molar specific of certain chemical elements. | French |
| 1742 - 1786 A.D. | Scheele | Discovered chlorine. | German |
| 1743 - 1794 A.D. | Lavoisier | Discovered that oxygen is one-fifth of air. | French |
| 1766 - 1844 A.D. | John Dalton | Proposed the atomic theory of matter. | English |
| 1776 - 1856 A.D. | Avogadro | Proposed Avogadro’s law that states equal volumes of gases under constant temperature and pressure contain an equal number of molecules. | Italian |
| 1778 - 1850 A.D. | Gay-Lussac | Discovered that water is composed of two parts hydrogen and one part oxygen by volume. Also discovered several chemical and physical properties of air and other gases. | French |
| 1796 - 1823 A.D. | Jacques Charles | Described the gaseous law. | French |
| 1779 - 1848 A.D. | J. J. Berzelius | Introduced symbols, formulas and chemical equations to make study more systematic. | Swedish |
| 1791 - 1867 A.D. | M. Faraday | Contributed to the study of electromagnetism and electrochemistry. | British |
| 1824 - 1904 A.D. | Mendeleev | Discovered the periodic arrangement of elements. | Russian |
| 1856 - 1940 A.D. | J. J. Thomson | Discovered the electron through experiments. | British |
| 1859 - 1927 A.D. | Arrhenius | Proposed acid-base theory and ions dissociation. | Swedish |
| 1871 - 1937 A.D. | Rutherford | Postulated the nuclear structure of the atom. Discovered alpha and beta rays, and proposed the laws of radioactive decay. | Scottish |
| 1879 - 1955 A.D. | Elbert Einstein | Proposed the fourth state of matter. | German |
| 1885 - 1962 A.D | Neil Bohr | Proposed a theory for the hydrogen atom based on quantum theory. | British |
| 1887 - 1961 A.D. | Schrodinger | Proposed a quantum mechanical model of the atom. | Australian |
| 1892 - 1987 A.D. | De Broglie | Proposed a hypothesis about wave particles and the duality of electrons. | French |
| 1894 - 1974 A.D. | Satyendra Nath Bose | Proposed the fourth state of matter along with Einstein. | Indian |
| 1951 - Alive | Carl Weiman | Synthesised the first Bose-Einstein Condensate. | American |
| 1961 - Alive | Eric Cornell | Produced the first Bose-Einstein Condensate. | American |