The Atomic Theory Timeline

By Jorgesar000
  • 400

    Democritus

    HISTORY OF THE ATOM FROM DEMOCRITUS TO BOHR AND SCHRÖDINGER
    His theory: Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained. This piece would be indivisible. He named the smallest piece of matter “atomos,” meaning “not to be cut.” (No exact month or date)

  • John Dalton

    All compounds have something in common. Dalton proposed the theory that all matter is made up of individual particles called atoms, which cannot be divided. Scientists found that not all of Dalton's ideas about atoms were completely correct.

  • J.J. Thomson

    Objects with like charges repel, or push apart. Objects with opposite charges attract, or pull together. Thomson's experiments provided the first evidence that atoms are made of even smaller particles. There aren't any problems/shortcomings with his theory.

  • Marie Curie

    Marie Curie and The Atomic Theory
    The ability to emit radiation does not depend on the arrangement of the atoms in a molecule; it must be linked to the interior of the atom itself.

  • Ernest Rutherford

    Ernest Rutherford discovered that uranium emits fast-moving particles that have a positive charge. Rutherford hypothesized that the mass and charge at any location in the gold would be too small to change the path of an alpha particle. He predicted that most particles would travel in a straight path from their source to a screen that lit up when struck. According to Rutherford's model, all of an atom's positive charge is concentrated in its nucleus. (No exact month or date)

  • Electron Cloud Model

    Electron Cloud ModelWhat date was the electron cloud model invented?
    The electron cloud model uses the concept of 'orbitals', referring to regions in the extra-nuclear space of an atom where electrons are likely to be found. (No exact month, date, or year.)

  • Niels Bohr

    Pearson SuccessNetIn Bohr's model, electrons move with constant speed in fixed orbits around the nucleus, like planets around a sun. Each electron in an atom has a specific amount of energy. If an atom gains or loses energy, the energy of an electron can change. e was incorrect in assuming that electrons moved like planets in a solar system

  • James Chadwick

    What are some problems with james chadwick's atomic theory?James Chadwick - Biographical
    Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons - elementary particles devoid of any electrical charge. There were no problems/shortcomings. (No actual date)

  • Hideki Yukawa

    Quantum Theory timelinecombines relativity and quantum theory to describe nuclear interactions by an exchange of new particles (mesons called "pions") between protons and neutrons. From the size of the nucleus, Yukawa concludes that the mass of the conjectured particles (mesons) is about 200 electron masses. This is the beginning of the meson theory of nuclear forces.

  • Enrico Fermi

    Enrico Fermi and the First Self-Sustaining Nuclear Chain Reaction
    "His discovery of new radioactive elements produced by neutron irradiation, and for the discovery of nuclear reactions brought about by slow neutrons."
    No problems/shortcomings.