L. Falconer Famous Dead Guy Timeline

  • 101

    Democritus - 429 BC

    First person to think of the atom.
    Thought atom was a sphere.
  • 102

    Aristotle - 400 BC

    He thought that everything was made up of one of the four elements.
    He did not believe in atoms.
  • Isaac Newton

    He believed that there were tiny pieces of mass "swimming" around everywhere.
  • John Dalton

    He discovered Atomic Theory.
    All matter is composed of atoms.
    Atoms can be made and destroyed.
    All atoms of the same element look the same.
    Different atoms have different types of atoms.
    Chemical reactions occur when atoms are rearranged.
    Compounds are formed from atoms of different elements.
  • Henri Becquerel

    He helped discover radioactivity.
  • J.J. Thomson

    He discovered electrons.
    Made the "plum pudding" model.
  • Robert Millikan

    He found the measure of the charge of an electron.
    He found the mass of an electron.
  • Ernest Rutherford

    Found that an atom has a central positive nucleus surrounded by negative orbiting electrons.
  • Neils Bohr

    He thought that the atom had a small positively charged nucleus with negatively charged surrounding electrons orbiting it.
  • Francis Aston

    He discovered 212 natural isotopes
    He invented the mass spectrometer.
  • Erwin Schrondinger

    Found that the atom has clouds of energy and that it has a nucleus.
    He made an equation to find out where the electron would be in an atom.
    He proved the Bohr model incorrect.
  • James Chadwick

    Discovered that neutrons are congruent to protons in weight.
    Discovered the neutron.