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460 BCE
Democritus (c. 460-370 B.C.E.)
Democritus theorized that all matter is made of infinite amounts of different combinations of tiny, indivisible, indestructible particles called atoms. -
Antoine Lavoisier (1743-1794)
Antoine Lavoisier introduced the Law of Conservation of Matter: the mass of all reactants is equal to the mass of the product. -
John Dalton (1766-1844)
John Dalton, an English chemist, found that each element has its own atom. These atoms each have a specific size and weight. -
JJ Thomson (1865-1940)
JJ Thomson, a British physicist and 1906 Nobel Prize winner, used his research in cathode rays to discover the electron. -
Marie Curie (1867-1934)
Marie Curie, a French physicist and two-time Nobel Prize winner, worked with her husband to discover and name radium and polonium. She also theorized that radioactivity is not affected by the structure of matter, but by its individual atoms. -
Robert Millikan (1868-1953)
Robert Millikan, an American Physicist and 1923 Nobel Prize winner, observed the effects of the charges carried by electrons by dropping oil into a chamber. -
Ernest Rutherford (1871-1937)
Ernest Rutherford, the "father of nuclear science", shot alpha particles at gold foil to determine the structure of an atom. He found that every atom had a small, dense nucleus at its center. -
Niels Bohr (1885-1962)
Niels Bohr, a Danish physicist, worked with other famous atomic scientists to come to two conclusions. The first is that electrons orbit around the nucleus of an atom in progressively larger groups. The number of electrons on the outermost orbit decides the chemical properties of the atom. -
Erwin Schrodinger (1887-1961)
Erwin Schrodinger, an Austrian theoretical physicist and 1933 Nobel Prize winner, theorized that electrons behave like waves. -
James Chadwick (1891-1974)
James Chadwick, a British Physicist and 1935 Nobel Prize winner, used his discoveries when working under Rutherford to discover and find the mass of the neutron.
