The History of the Atomic Model

By LadyKnightengale
  • 465 BCE

    Democritus

    Democritus
    Democritus first theorized the atom, and determined that they are indestructible.

  • John Dalton

    John Dalton
    Dalton determined that different types of atoms had different masses, elements contain only one type of atom, and that atoms rearrange in chemical reactions.

  • E. Goldstein

    Goldstein discovered positively charged ions, or protons.

  • Marie Curie

    Marie Curie discovered the elements Radium and Polonium.

  • J.J. Thompson

    J.J. Thompson
    Thompson discovered the electron.

  • Ernest Rutherford

    Ernest Rutherford
    Rutherford found that positive charge was in center of the nucleus of an atom, and the electrons orbited the nucleus.

  • Robert Millikan

    Millikan found the charge of the electron is a multiple of 1.59 x 10-19 C, and the mass of an electron is always 1000 times smaller than the smallest atom.

  • Neils Bohr

    Neils Bohr
    Bohr found that electrons move closer to the nucleus when energy is released, and each layer of energy is its own electron “shell”.

  • James Chadwick

    Chadwick discovered the neutron.
  • Period: to

    Quantum Mechanical Model (also known as the Wave Model)

    Illustrates the shape of the electron cloud around the nucleus, as electrons don't have a direct path.