History of Atom

  • 101

    Democritus - 429 B.C.

    First person to think that all matter is made of atoms
  • 101

    Aristotle - 400 B.C.

    Believed that everything was made of the four elements
  • Sir Issac Newton

    Also believed that all mattrer was made of atoms.
  • Dalton

  • J.J. Thompson

    Proved existence of electrons
  • Henri Bacquerel

    Discovered radioactivity
  • Robert Andrews Millikan

    Mass of electron at least 10,000X smaller than smallest atom.
  • Rutherford

    Found nucleus and proton
  • Bohr

    Electrons travel in orbits around nucleus
  • Francis Aston

    Discovered isotopes