Atomic Theories

  • Democritus
    400

    Democritus

    Link All things are composed of invisible tiny particles of matter, which can’t be destroyed.
  • Period: 400 to

    Atomic Theories

  • John Dalton

    John Dalton

    NNDB Described tiny indivisible particles called atoms.
    Atoms can’t be divided or destroyed.
    Atoms can join together to form molecules.
    Atoms of one element are all the same.
  • J.J. Thomson

    J.J. Thomson

    noble prize Atoms contain electrons, which have a negative charge.
    Atoms are solid with electrons and protons randomly placed through them.
  • Ernest Rutherford/Thompson

    Ernest Rutherford/Thompson

    nobel prize Atoms have a dense nucleus which contains protons, and most of the rest is empty space.
    Electrons orbit around the nucleus like planets around the sun.
  • Niels Bohr

    Niels Bohr

    Noble prize Electrons are arranged in layers or shells around the nucleus.
    The shells have different energy levels, and electrons fill up the lowest levels first.
  • James Chadwick

    James Chadwick

    noble prize The nucleus also contains neutrons, which are unchanged particles with a similar mass to protons.