Atomic Model Timeline

  • 322

    Aristotle

    Aristotle
    332 B.C He developed methods and helped contribute to the gathering of scientific fact. The work that he did became the basis for all scientific work for more than a millenium..
  • Period: 322 to

    Timeline of Atomic Theory

    The real start date for this timeline is Democritus' theory of the atomic model in 322 BC, but since this timeline doesnt go before the Birth of Christ, I just left it off at 442. Also, for some of these events, there was no exact date given (just the year) so I just uploaded the event date as January 1st since there is no option to leave it blank.
  • 442

    Democritus

    Democritus
    442 B.C Democritus theorized that the universe is made up of empty space and rearly infinite numbers of invisble particles. These particles can vary from form, arrangement, and position. He believed that all matter is composed of atoms.
  • Isaac Newton

    Isaac Newton
    He conducted an experiment proposing the theory of a mechanical universe with small solid masses in motion by modelling the atom using billard balls.
  • Lavoisier

    Lavoisier
    Lavoiser explained the mysteries of fire through his discvories of the conservation of matter.
  • Coulomb

    Coulomb
    He formed Coulomb's Law which stated that the force one tiny charged object exerts on a second one is proportional to the amount of charge on one times the amount of charge on the others and inversely proportional to the square of the distance
    between them.
    F=Q1*Q2/r²
  • John Dalton

    John Dalton
    Dalton was and English chemis who proposed one of the first kown Atomic Theories which stated that all matter was composed of amall indivisble particles called atoms. He felt that they all had different characteristics to them. He also stated that three types of atoms exist which were simple (elements), compound (simple molecules), and complex (complex molecules).
  • J.Plucker

    J.Plucker
    He built the Cathode Ray Tube which was one of the first known gas discharge tubes ever invented.
  • Dmitri Mendeleeve

    Dmitri Mendeleeve
    He arranged elements into 7 groups with similar properties. He grouped elements which smiliar properties in order from weight and mass. This is what we call the Periodic Table.
  • G.J. Stoney

    G.J. Stoney
    He was the first person to purpose that electricity was made of discrete negative particles called electrons.
  • Wilhelm Roentgen

    Wilhelm Roentgen
    He discovered what we now know as x-rays t while using a CRT as he observed chemicals and rays penetradting through because they were not deflected by the magnetic field.
  • J.J. Thomson

    J.J. Thomson
    He was the first person to measure the electron through his experiment of the plump-pudding model of the atom. It describes the atom as slightly positive sphere with small electrons inside.
  • Albert Einstein

    Albert Einstein
    Einstein introduces his special theory of relativity and the mathematical formula E=mc^2, which can also be stated by the mass multiplied by the speed of light spared which converts to energy.
  • R.A. Millikan

    R.A. Millikan
    He discovred and verified the negative charge of an electron through his oil drop experiment.
  • Ernest Rutherford

    Ernest Rutherford
    He established that the nucleus was very dense, very small and positively charged through his gold foil experiment. He also assumed that the electrons were located outside the nucleus.
  • H.G.J. Moseley

    	H.G.J. Moseley
    He discovered that the atomic number of an element is egual to the number of protoms in the nucleus. This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
  • Aston

    Aston
    Francis Aston discovered the existence of isotopes through the use of a mass spectrograph.
  • Niels Bohr

    Niels Bohr
    He stated that electrons could only orbit the nucleus in succesively larger orbits around the nucleus. The ectrons in the outermost shell determine the properties of the atom. He also inferred that when an electron moves from an outer orbit to an inner orbit, the shells begin to quantim.
  • James Chadwick

    James Chadwick
    By exposing the metal berylium to alpha particles in one of his experiments, he discovers the neutron.
  • Enrico Fermi

    Enrico Fermi
    Conducted the first controlled chain reaction releasing energy from the atoms nucleus, he called this invention the Chicago Pile 1.
  • Hiroshima

    Hiroshima
    On this date, the United States drops the first atomic bomb on Hiroshima. His 20 kiloton bomb named "Little Boy" killed over 80,000 people and afftect many other survivors by radiation.
  • Nagasaki

    Nagasaki
    The United States drops atomic bomb on Nagasaki in Japan. The 22 kiloton bomb named 'Fat Man', killed 70,000 people.
  • Atomic Energy Act of 1954

    Atomic Energy Act of 1954
    The U.S. Congress passed an atomic energy act allowing the Atomic Energy Commission to license private companies to use nuclear materials and build nuclear power plants
  • The USS Nautilus SSN 571

    The USS Nautilus SSN 571
    The United States created its first nuclear powered submarine called the USS Nautilis.
  • Undergroung Nuclear Test

    Undergroung Nuclear Test
    The United States sets off its first undergroung nuclear test in the desert mountains 100 miles from Las Vegas.
  • Nuclear Reactor

    Nuclear Reactor
    The first ever nuclear reactor is operated on from outter space.
  • Three Mile Island Accident

    Three Mile Island Accident
    The Three Mile Island accident began at 4 a.m on a Wednesday morning when reports of redioactive isotopes were reported to be released into the atmosphere from this site.