Atomic Theory Timeline

  • John Dalton's Atomic Weights

    John Dalton created the first atomic weights chart. When he did this, he became the first scientist to explain the behavior of atoms in the terms of measurement in weights. He did this through studying the Greek philosopher, Democritus of Abdera's theory of matter.
  • John Dalton's atoms

    John Dalton discovered the fact that atoms could not be created or destroyed.
  • Marie and Pierre Curie's Elements

    Marie and Pierre Curie discovered radium and polonium in 1898. They did this using an electrometer. Marie measured the radiation that was given off from uranium compounds. They also detected a similiar radiation in compounds of thorium. This radiation was uninfluenced by external conditions. When she checked her results, she found the pitchblend contained small amounts of unknown radiating elements.
  • Marie Curie's 1st Nobel Prize

    Marie Curie's 1st Nobel Prize for Physics was awarded in 1903.
  • Marie Curie's 2nd Nobel Prize

    Marie Curie won her second Nobel Prize for Chemistry in 1911.
  • The Bohr Model

    Neils Bohr created the Bohr model during 1913. He discovered how to make a Bohr model through his discovery of the structure of atoms. His creation had left two questions remaining: why are there only a limited number of orbits in which the electron can reside in a hydrogen atom? And, why can't this model be extended to many-electron atoms?
  • Albert Einstein's Relativity Theory

    Albert Einstein developed his Theory of Relativity while he was trying to rewrite the laws of mechanics from Newtonians' theories.
  • Albert Einstein's Nobel Prize

    Albert Einstein won the Nobel Prize for Physics in 1921.
  • Neils Bohr's Nobel Prize

    Neils Bohr won the Nobel Prize for Physics for 1922.
  • Arthur Compton's Discovery

    Arthur Compton discovered that the increase of wavelength of X- ray is caused by the scattering of the radiation by free electrons. This implies that the scattered quanta have less energy than the quanta of the original beam. He discovered these things from experimenting with a theory of the intensity of X-ray reflection, which he began acting on in 1918.
  • The Geiger-Mueller Counter

    In 1925, Hans Geiger helped perfect the Geiger-Mueller Counter at the University of Kiel in Germany. This counter can be used to locate an alpha particle in a square centimeter of space. It can also be used to count subatomic particles. Geiger used this machine to confirm the exsistence of packets of energy known as light quantum.
  • Werner Heisenberg's Quantum Mechanics

    Werner Heisenberg developed the theory of Quantum Mechanics. This theory resulted in the discovery of allotropic forms of hydrogen.
  • Enricho Fermi's Statistical Laws

    Enricho Fermi discovered Statistical Laws. It is known today as Fermi statistics. These statistics govern the particles subject to Pauli's Exclusion Principle.
  • The Wave Nature of Electrons

    Louis de Broglie discovered the wave-like nature of electrons which he had discovered through a thesis that had been written years earlier. By investigating the discovery of electron diffraction, the wave nature was found.
  • Arthur Compton's Nobel Prize

    Arthur Comtpon won the Nobel Prize for Physics in 1927.
  • Paul Dirac's Electron and Holes Theory

    Paul Dirac developed this theory when he began to study quantum mechanics. The latter theory required the existence of a positve particle that has the same mass and charge as the electrom. (This positive particle would be discovered to be the positron).
  • Louis de Broglie's Nobel Prize

    Louis de Broglie earned the Nobel Prize for Physics in 1929.
  • Otto Frisch and the Proton

    Around 1930, Otto Frisch was the first to prove that the magnetic movement of the proton was larger than anyone had previously predicted.
  • James Chadwick's Neutron

    James Chadwick discovered the neutron by using scattering data to calculate the mass of this neutral particle.
  • Werner Heisenberg's Nobel Prize

    Werner Heisenberg won the Nobel Prize for Physics in 1932.
  • The Positron

    Carl Anderson discovered the positive electron, commonly referred to as the positron. He discovered it by allowing rays to pass through a cloud chamber in a strong magnetic field. This was a revolutionary discovery because it was the first known antiparticle and also the first known positively charged particle other than the proton. It was discovered the Anderson's positron was the particle missing from P.A.M. Dirac's relativistic quantum-mechanical theory of the electron.
  • Paul Dirac's Nobel Prize

    Paul Dirac won the Nobel Prize for Physics in 1933.
  • Enricho Fermi's Neutrons

    Enricho Fermi discovered slow neutrons that led to the discovery of nuclear fission and the production of elements lying beyond the Periodic Table.
  • James Chadwick's Nobel Prize

    James Chadwick won the Nobel Prize for Physics in 1935.
  • Carl Anderson's Nobel Prize

    Carl Anderson won the Nobel Prize for Physics.
  • Enricho Fermi's Nobel Prize

    Enricho Fermi won the Nobel Prize in Physics in 1938.
  • Otto Frisch's Uranium Experiment

    Otto Frisch along with another physicist demonstrated that the fissioning of Uranium 235 would create a devasting explosion. Doing this would create a very powerful, destructive weapon of war.
  • The Source Theory

    Richard Feynman and Julian Schwinger developed the Source Theory. This deals with strongly interacting protons, particles, and gravitons. They achieved this following their own advice about the parcticle importance of a phenomenological theory of particles.
  • Richard Feynman and Julian Schwinger Nobel Prizes

    Richard Feynman and Julian Schwinger won the Nobel Prize for Physics in 1965.
  • Murray Gell-Man & George Zweig's Nobel Prize

    Murray Gell-Man & George Zweig won the Nobel Prize for Physics in 1969.
  • Murray Gell-Mann and George Zweig's Discovery

    These two men proposed all hadrons were composed of particles called quarks. They finally discovered this in 1975 and are presently thought to be fundamental particles of matter.