Atomic Theory

By Malliikk
  • 400 BCE

    400 B.C.E The Beginning

    Democritus made the theory that all matter is made up of small, indestructible units he called "atoms".

  • Dalton on the Scene

    John Dalton proposed elements were made of atoms that were identical and had the same mass and that compounds were atoms from different elements combined together.

  • Cathode-Ray of Plucker

    Julius Plucker built one of the first cathode-ray tubes.

  • Periodic Table of Mendeleev

    Dmitri Mendeleev created the first periodic table based on atomic masses.

  • It's Electric: Stoney Advances

    G.J Stoney theorized that electricity was comprised of negative particles called electrons.

  • Rays of Roëntgen

    Wilhelm Roëntgen discovered x-rays.

  • Rutherford & Radiation

    Ernest Rutherford discovered alpha, beta, and gamma rays in radiation.

  • Marie Curue & Radioactivity

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

  • Soddy Coins Isotopes

    Fredrick Soddy came up with the term "isotope" to explain the unintentional breakdown of radioactive elements.

  • Nagaoka's Saturian Model

    Hantaro Nagaoka proposed an atomic model called the Saturian Model to describe the structure of an atom.

  • Moseley Revamps the Table

    H.G.J Moseley discovered that the number of protons in an element determines its atomic number and created a modern periodic table.

  • Bohr & Electrons

    Niels Bohr proposed an atomic structure theory that stated the outer orbit of an atom could hold more electrons than the inner orbit.

  • Fission With Meitner, Hahn, and Strassman

    Lise Meitner, Hahn, and Strassman discovered nuclear fission.

  • Chadwick Neutrons

    James Chadwick discovered neutrons, particles whose mass was close to that of a proton.