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Joseph Proust
In 1799, Joseph Proust discovered the Law of Definite Proportion which states that a chemical compound always contains exactly the same proportion of elements by mass. -
John Dalton
In 1800, he developed the atomic theory. -
Amedeo Avogado
In 1811, Avogadro's law states that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. -
Dmitri Mendeleev
In 1869, Mendeleev created the first periodic table of elements, and he used it to predict the elements not discovered yet. -
JJ Thomson
In 1869, Thomson and his two partners, John S. Townsend and H. A. Wilson, performed experiments indicating that cathode rays were unique particles. They discovered the electron. -
Marie Curie
In 1898, Marie and her husband Pierre wrote a paper revealing the existences of radioactivity and two elements, polonium and radium. -
Hans Geiger
In 1909, Hans Geiger was the co-inventor of the Geiger counter and participated in the Geiger-Marsden experiment which discovered the Atomic nucleus. -
Niels Bohr
In 1913, Niels Bohr discovered that electrons resided in levels with the energy determined by electron's orbits around the nucleus. He believed that the electrons could move between the levels by absorbing photons at specific frequencies. -
Ernest Rutherford
In 1914, Rutherford discovered that the structure of an atom has a nucleus of positive charges surrounded by the negatively charged electrons. -
Enrico Fermi
In 1939, Fermi and his partner Leó Szilárd created the first artificial self-sustaining nuclear chain reaction.
