15 contributers to the atomic theory

Timeline created by HarrisonKelly
  • 490

    Democritus

    Democritus
    Democritus stated "by convention bitter, by convention sweet, but in reality atoms and void"
  • Isaac Newton

    Isaac Newton
    Proposed a mechanical universe with small solid masses in motion
  • 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 Mendeleev

    Dmitri Mendeleev
    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.
  • James clerk Maxwell

    James clerk Maxwell
    Proposed electric and magnetic fields filled the void.
  • Sir William crookes

    Sir William crookes
    Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass.
  • E. Goldstein

    E. Goldstein
    Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.
  • G.J. Stoney

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

    Wilhelm roentgen
    Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays".
  • Henri Becquerel

    Henri Becquerel
    While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
  • J.J. Thompson

    J.J. Thompson
    Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. Studied "canal rays" and found they were associated with the proton H + .
  • Rutherford

    Rutherford
    Studied radiations emitted from uranium and thorium and named them alpha and beta.
  • Marie Sklodowska Curie

    Marie Sklodowska Curie
    Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium.