Stated radiation law and Planck's constant.
Soddy (1900)
Observed spontaneous disintegration of radioactive elements into 'isotopes' or new elements, described 'half-life', made calculations of the energy of decay.
Kistiakowsky, George B. (1900-1982)
Devised the detonating device used in the first atomic bomb.
Heisenberg, Werner K. (1901-1976)
Developed the orbital theory of chemical bonding. Described atoms using a formula related to the frequencies of spectral lines. Stated the Uncertainity Principle (1927). Nobel Prize in 1932.
Fermi, Enrico (1901-1954)
First to achieve a controlled nuclear fission reaction (1939/1942). Performed fundamental research on subatomic particles. Nobel Prize in 1938.
Nagaoka (1903)
Postulated a 'Saturnian' atom model with flat rings of electrons revolving about a positively charged particle.
Abegg (1904)
Discovered that inert gases have a stable electron configuration which results in their chemical inactivity.
Geiger, Hans (1906)
Developed an electrical device which made an audible 'click' when hit with alpha particles.
Lawrence, Ernest O. (1901-1958)
Invented the cyclotron, which was used to create the first synthetic elements. Nobel Prize in 1939.
Libby, Wilard F. (1908-1980)
Developed carbon-14 dating technique. Nobel Prize in 1960.
Ernest Rutherford and Thomas Royds (1909)
Demonstrated that alpha particles are doubly ionized helium atoms.
Bohr, Niels (1913)
Devised quantum model of the atom in which atoms had orbital shells of electrons.
Milliken, Robert (1913)
Experimentally determined the charge and mass of an electron using an oil drop.
Crick, F.H.C (1916- ) with Watson, James D.
Described the structure of the DNA molecule (1953).
Woodward, Robert W. (1917-1979)
Synthesized many compounds, including cholesterol, quinine, chlorophyll and cobalamin. Nobel Prize in 1965.
Aston (1919)
Use a mass spectrograph to demonstrate the existence of isotopes.
de Broglie (1923)
Described the particle/wave duality of electrons.
Heisenberg, Werner (1927)
Stated the quantum uncertainty principle. Described atoms using a formula based on the frequencies of spectral lines.
Cockcroft / Walton (1929)
Constructed a linear accelerator and bombarded lithium with protons to produce alpha particles.
Schodinger (1930)
Described electrons as continuous clouds. Introduced 'wave mechanics' to mathematically describe the atom.
Dirac, Paul (1930)
Proposed anti-particles and discovered the anti-electron (positron) in 1932. (Segre/Chamberlain detected the anti-proton in 1955).
Chadwick, James (1932)
Discovered the neutron.
Anderson, Carl (1932)
Discovered the positron.
Pauli, Wolfgang (1933)
Proposed the existence of neutrinos as a means of accounting for what appeared to be a violation of the law of conservation of energy in some nuclear reactions.
Fermi, Enrico (1934)
Formulated his theory of beta decay.
Lise Meitner, Hahn, Strassman (1938)
Verfied that heavy elements capture neutrons to form fisionable unstable products in a process which ejects more neutrons, thus continuing the chain reaction.
Seaborg, Glenn (1941-1951)
Synthesized several transuranium elements and suggested a revision to the layout of the periodic table.
