Atomic Theory- Hannah

  • 400

    Democritus

    Matter is made of invisible particles called atoms.
  • John Dalton

    Proposed an atomic theory with the spherical sold masses in motion.
  • Wilhelm Roentgen

    Discovered the x-ray.
  • X-ray

    First x-ray was discovered.
  • J.J Thomson

    Described that atom as a ball of positive charge containing a number of electrons. *Discovered the electron
  • Marie Curie

    Discovered polonium.
  • Ernest Rutherford

    Created the "gold foil" experiment to determine that the nucleus of the atom is very dense and has a positive charge. Assumed electrons were outside the nucleus of the atom.
  • Neils Bohr

    Explained the atomic structure of the atom as "succesive orbital shells of electrons." Model known as Bohr Planetary Model.
  • Scrodinger

    Identified that electron cloud model as the probable location of moving electrons.
  • Chadwick

    Discovered a particle within the nucleus that has a mass simillar to that of a proton. *Discovered the proton.
  • Cockroft/Walton

    Split the atom.
  • Build the atomic bomb

    Bomb was dropped on Japan to end World War 2.
  • First SNAP-3A

    SNAP-3A fueled with polonium, provided power to a satellite radio transmitter. President Eisenhower peace message was broadcast via satellite containing a radio transmitter powered by the SNAP-3A.