B8a611726841a157c7cfcbc71e140749f17360bf original

Atomic Theory

By nfriendshuh
  • 442 BCE

    Democritus

    Democritus
    Democritus was a Greek philosopher and scientist who first proposed the theory that matter is comprised of minuscule particles that he called "atomos." He created the first atomic model, which depicted atoms as having no structure, solid, and differing in size, shape, mass, position, and arrangement.

  • John Dalton

    John Dalton
    John Dalton was an English physicist, chemist, and meteorologist who, in 1803, introduced an atomic model wherein the atoms are solid, spherical, and have measurable mass.

  • Michael Faraday

    Michael Faraday
    Faraday was a British physicist whose experiments with electrodes introduced the idea that atoms have electrical properties

  • Henri Becquerel

    Henri Becquerel
    Henri Becquerel was a French physicist who discovered the existence of radioactivity. He did so by performing experiments with uranium and other substances.

  • J.J. Thomson

    J.J. Thomson
    J.J. Thomson was an English physicist who first discovered the electron. He did so by using a cathode ray tube to demonstrate how the current model of an atom did not account for both positive and negative charges. Thomson then proposed his plum pudding model of the atom.

  • Ernest Rutherford

    Ernest Rutherford
    Ernest Rutherford was a British physician who happened to be a former student of J.J. Thomson. Rutherford proved Thomson's plum pudding model incorrect with his gold foil experiment, which proved that an atom has a nucleus- in which a few, dense positive charges are housed with the electrons surrounding it.

  • Niels Bohr

    Niels Bohr
    Bohr was a Danish physicist who proposed an improved atomic model wherein the electrons are arranged in concentric orbits around the nucleus. Bohr likened this model to the solar system, and so, it is thought of as the planetary model.

  • Werner Heisenberg

    Werner Heisenberg
    Heisenberg was a German theoretical physicist, and he is known for developing the uncertainty principle, which stated that it is impossible to discern both the exact speed and location of electrons. This led to the modern quantum model of the atom.

  • Erwin Schrödinger

    Erwin Schrödinger
    Schrodinger was an Austrian physicist that developed the quantum mechanical model, which helps to predict the location of an electron.

  • James Chadwick

    James Chadwick
    James Chadwick was a British physicist who discovered the presence of neutrons within the nucleus.

  • Murray Gell-Man & George Zweig

    These two men proposed the theory of "quark" flavors.