History of Periodic table

  • 400

    . Democritus’ Atomic theroy

    400 B.C. Democritus’ atomic theory posited that all matter is made up small indestructible units he called atoms. "by convention bitter, by convention sweet, but in reality atoms and void"
  • Issacc Newtons Theory

    1704 Isaac Newton theorized a mechanical universe with small, solid masses in motion.
  • John Dalton propostion

    1803 John Dalton proposed that elements consisted of atoms that were identical and had the same mass and that compounds were atoms from different elements combined together.
  • 1859 J. Plucker built one of the first cathode-ray tubes.

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

    Dmitri Mendeleev created the periodic table.
  • James Clerk Maxwell

    1873 James Clerk Maxwell proposed the theory of electromagnetism and made the connection between light and electromagnetic waves.
  • G.J Stoney

    G.J. Stoney theorized that electricity was comprised of negative particles he called electrons.
  • Sir William Crookes'

    experiments with cathode-ray tubes led him to confirm the work of earlier scientists by definitively demonstrating that cathode-rays have a negative charge.
  • E. Goldstein

    E. Goldstein discovered canal rays, which have a positive charge equal to an electron.
  • Wilhelm

    Wilhelm Roentgen discovered x-rays.
  • Henri Becquerel

    Henri Becquerel discovered radiation by studying the effects of x-rays on photographic film.
  • J.J. Thomson

    1897 J.J. Thomson determined the charge to mass ratio of electrons.
  • Rutherford

    Rutherford discovered alpha, beta, and gamma rays in radiation.
  • Marie Sklodowska Curie

    Marie Sklodowska Curie discovered radium and polonium and coined the term radioactivity after studying the decay process of uranium and thorium.
  • Max Planck

    Max Planck proposed the idea of quantization to explain how a hot, glowing object emitted light.
  • Frederick Soddy

    1900 Frederick Soddy came up with the term "isotope" to explain the unintentional breakdown of radioactive elements.
  • 945 Glenn Seaborg

    In 1945 Glenn Seaborg identified lanthanides and actinides (atomic number >92), which are usually placed below the periodic table.
  • Hantaro Nagaoka

    1903 Hantaro Nagaoka proposed an atomic model called the Saturnian Model to describe the structure of an atom.
  • Richard Abegg

    1904 Richard Abegg found that inert gases have a “stable electron configuration.”
  • Hans Geiger

    1906 Hans Geiger invented a device that could detect alpha particles.
  • H.G.J. Moseley

    H.G.J. Moseley discovered that the number of protons in an element determines its atomic number.
  • Michael Faraday Laws

    1832 Michael Faraday developed the two laws of electrochemistry