History of the Atomic Theory Timeline

Timeline created by #HunterSwag
  • 384

    Aristotle

    Aristotle
    Aristotle stated that all matter is made up of the four elements: fire, water, earth and air. His statement was quite generalized and did not come from evidence rather from theories and religious beliefs. There were also four qualities for the elements: dryness, hotness, coldness, and moistness.
  • 460

    Democritus

    Democritus
    Democritus claimed that everything is made up of atoms, as he also said atoms could be physically divided but no geometrically. Democritus claimed atoms were constantly moving and there are an infinite number of them which are indestructible and always will be.
  • Isaac Newton

    Isaac Newton
    Proposed a mechanical universe with small masses in motion which was had given him the title of having a better perspective on atoms.
  • John Dalton

    John Dalton
    Developed the first useful atomic theory of matter, with spherical solid atoms based upon measureable properties of mass.
  • Michael Faraday

    Michael Faraday
    Claimed the term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis.
  • J. Plucker

    J. Plucker
    Created one of the first gas discharge tubes.
  • Dmitri Mendeleev

    Dmitri Mendeleev
    Dmitri 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".
  • James Chadwick

    James Chadwick
    James Chadwick was the discoverer of the neutron. His experiment was to bombard a thin sheet of beryllium with alpha particles. After the experiment he found that the gamma rays emitted from the beryllium contained a third subatomic particle, the neutron.
  • William Conrad Roentgen

    William Conrad Roentgen
    Discovered x-rays while using cathode-ray tubes. Found that x-rays could pass through solid objects.
  • George Johnston Stoney

    George Johnston Stoney
    George Stoney’s most famous work was his conception and calculation of the magnitude of the atom or particle or electricity.
  • 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.
  • Joseph John Thomson

    Joseph John Thomson
    In 1912 Joseph Thomson channelled a stream of ionized neon though a magnetic and electric field.In this this he discovered that neon was made of two different types of atoms, this proved the existence of isotopes.
  • Niels Bohr

    Niels Bohr
    Niels Bohr stated that electrons in an atom do not behave the same as the planets do around the sun. They move about the nucleus in a circular orbit at different distances, the more the energy the further the orbit is from the nucleus.
  • Ernest Rutherford

    Ernest Rutherford
    Studied radiations emitted from uranium and thorium and named them alpha and beta. Rutherford established that the nucleus was: very dense,very small and positively charged aswell as he also thought that the electrons were located outside the nucleus.