Atom molecule

Atomic Theory Timeline

  • 460


    460 B.C. - Greek philosipher who was one of the first suggested atoms exist.
  • Joseph Proust

    Joseph Proust
    Proust composed the Law of Constant Composition, which was that the composition of the substance is always the same no matter where it was made or found.
  • John Dalton

    John Dalton
    Pictured atoms as extremely small and indestructable particles with with no internal substance. This led to Dalton's atomic theory,
  • J.J. Thomson

    J.J. Thomson
    Discovered the electron and invented the cathode ray, which passes electric currents throught gases at a low pressure.
  • Max Planck

    Max Planck
    Plank proposed the Plank’s constant h, explaining that the pattern of light intensity. Planck’s claim was that energy is carried in tiny units, which he named “quanta”.
  • Invention of the airplane

    Invention of the airplane
  • Ernest Rutherford

    Ernest Rutherford
    Rutherford and a few of his coworkers used massive alpha particles (atoms that have a doubly positive charge) and moved them through a thin sheet of gold foil. Most of the particles passed through the gold atoms, but a small amount deflected off at weird angles. Rutherford’s new atomic model showed that the atom is mostly empty except for the protons and neutrons inside a nucleus in the middle.
  • Niels Bohr

    Niels Bohr
    Proposed an electron is found only in a specific orbit around the nucleus
  • Period: to

    World War I

  • Robert Millikan

    Robert Millikan
    Millikan used a constructed valve and the “charge-to-mass ratio of an electron used by Thomson, he measured the electron’s mass. An electron carries one negative charge and the mass is 1/1840 of a hydrogen atom.
  • Louis de Broglie

    Louis de Broglie
    de Brogile makes a claim that since light has waves, that particles have waves as well. He claimed that moving electron particles have properties of wave.
  • Erwin Schrodinger

    Erwin Schrodinger
    Develops mathematical equations to describe motion of electrons in atoms. He created the electon cloud model and the quantum mechanical model.
  • Werner Heisenberg

    Werner Heisenberg
    Heisenberg claims that it is impossible to know the velocity and the position of a particle at the same time.
  • Period: to

    The Great Depression

  • James Chadwick

    James Chadwick
    Discovers neutrons which have no charge and reside in the nucleus with protons.
  • Period: to

    World War II

  • 1st Helicopter

    1st Helicopter
    The World's first helicopter takes flight
  • Penicillin

    Goes into the common use for common diseases.
  • Israel

    Comes into first existance and a Jewish state
  • The McCarthy Witchhunt

    The McCarthy Witchhunt
    The Witchhunt hearings took place in the USA.

    First satelite to orbit the earth - it was a Russian spacecraft.
  • NASA founded

    NASA founded
  • Muhatma Ghandi

    Muhatma Ghandi
    Is arrested in India for demanding independence from England
  • Aristotle

    384 B.C.- Aristotle believed that the four elements of air, earth, water, and fire could always be broken down into more matter and always be divided.