Discoveries of the Atom

By TymeTst
  • 460 BCE

    Democritus

    Democritus was the first to discover the basics of an atom and determined they were too small to be seen.
  • 400 BCE

    Alchemy

    Medieval chemistry!
  • 340 BCE

    Aristotle

    He believed everything was made up of the four elements of the known world; water, fire, air, and earth.
  • 1492

    Columbus comes to America

  • Robert Boyle

    Robert Boyle discovered that the pressure of gas increases as the volume of the container decreases.

  • American Revolution

  • John Dalton

    John Dalton took Democritus's theory and made it into reality. He was the first to make a real model of an atom.

  • American Civil War

  • Dmitri Mendeleev

    Dmitri Mendeleev was the one who arranged the elements in order according to their mass.

  • J.J. Thomson

    J.J. Thomson made the plum pudding model. He also thought that atoms had positive/ negative cores and theorized that atoms could be divided.

  • Robert Milliken

    Robert Milliken performed the oil drop experiment which determined the charge of an electron.

  • Ernest Rutherford

    Ernest Rutherford discovered that there is a electron cloud around the outside of the atom.

  • Hans Geiger

    Hans Geiger helped to discover individual particles.

  • Neils Bohr

    Neils Bohr created the Bohr model.

  • WWI

  • James Chadwick

    James Chadwick discovered the neutron in the atom.

  • WWII

  • Hiroshima