Stylised atom with three bohr model orbits and stylised nucleus

History of the Atom

By Mat P
  • 460 BCE

    Democritus' Contribution

    Democritus said that matter consists of really small, indivisible particles; Atoms.

  • John Dalton's Contribution

    All matter is made of atoms, which are indivisible and indestructible.
    All atoms of a given element are identical.
    Compounds are formed by a combination of two or more different kinds of atoms.
    A chemical reaction is a rearrangement of atoms.

  • JJ Thomson's Contribution

    JJ Invented the ‘Plum Pudding’ model - atoms have a positive sphere (pudding) with negative electrons (plums) dispersed throughout.

  • Ernest Rutherford's Contribution

    Ernest discovered nucleus of atoms. Invented the ‘nuclear’ model - atoms hava a dense positive nucleus surrounded by negative electrons.

  • Niels Bohr's Contribution

    Niels invented the ‘Planetary’ model - atoms have electrons that move in circular orbits within specific energy levels.

  • James Chadwick's Contribution

    Revised ‘Nuclear’ model – atoms have a neutral particle in the nucleus (neutrons).