Scientists that Contributed to the Atomic Theory

  • Isaac Newton

    Isaac Newton
    Proposed a mechanical universe with small solid masses in motion.
  • Period: to

    Timespan of the Atomic Theory

  • John Dalton

    John Dalton
    Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
  • Michael Faraday

    Michael Faraday
    Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism
  • J. Plucker

    J. Plucker
    Built one of the first gas discharge tubes ("cathode ray tube").
  • Dmitri Mendeleeff

    Dmitri Mendeleeff
    Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
  • G.J. Stoney

    G.J. Stoney
    Proposed that electricity was made of discrete negative particles he called "electrons". (Link to info on electrons)
  • J.J. Thomson

    J.J. Thomson
    Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 108 coulombs/gram.
  • Rutherford

    Studied radiations emitted from uranium and thorium and named them alpha and beta. And using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil. He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
  • Soddy

    Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.
  • H.G.J. Moseley

    H.G.J. Moseley
    Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
  • Francis William Aston

    Francis William Aston
    Discovered the existence of isotopes through the use of a mass spectrograph.
  • Niels Bohr

    Niels Bohr
    Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons.
  • de Broglie

    de Broglie
    Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
  • James Chadwick

    James Chadwick
    Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
  • Enrico Fermi

    Enrico Fermi
    CitationsConducted the first controlled chain reaction releasing energy from the atoms nucleus.