The history of atomic theory

Timeline created by 4lex Mer
  • -430 BCE


    Democritus made very significant observations, he stated that atoms are the building blocks for all things and that atoms are tiny, indivisible, and differ only by shape and arrangement. He also stated that atoms cannot be destroyed and that atoms correspond to the substance that they make.
  • -300 BCE


    Around 300BC Aristotle didn’t believe that atoms were of different sizes and had regular geometric shapes which contradicted societies belief for his day. He believed all matter contained fire, air, earth, water, and ether, emotions of the world contributed to good and bad.
  • Lavoisier

    Lavoisier did many experiments with gases, he basically discovered oxygen and hydrogen. When some substances were burned he stated that their loss in mass was gas molecules escaping into the atmosphere which led him to establish the Law of Conservation of Mass.
  • Dalton

    John Dalton published his Theory on atoms which stated;
    • All elements are made up of tiny indivisible particles, known as atoms
    • Atoms of the same element are identical with respect to their weights
    • Atoms of different elements are different from each other and can be identified by their relative weights
    • Atoms can neither be divided into smaller particles nor destroyed
    He also expanded upon the idea of definite proportions and the Law of Multiple
  • Mexican Independence

    Mexican Independence
    It started with "El Grito de Dolores". Some impotant characters are:
    - Miguel Hidalgo
    - Maria Morelos
    - Josefa Ortiz de Domínguez
    - Ignacio Allende
    - Agustin de Iturbide
  • Thomson

    He created a tube with a positively charged anode side and a negatively charged cathode side which made sort of a beam then he placed a magnet in the middle and the beam bended toward the positive end of the magnet meaning the particles in the beam were negatively charged thus electrons.
  • Planck

    He discovered that electromagnetic energy is released in quantized specific amounts. In the formula to find the amount of energy that is released when electrons jump energy levels, h is plancks constant
  • Rutherford

    He did the famous gold foil experiment in 1908. He shot alpha particles at gold foil, most of them went right through the foil but some were reflected meaning there was a small, dense, positive charged area he called it a nucleus of an atom.
  • Mexican Revolution

    Mexican Revolution
    It was a major armed struggle resulted from the failure of the 31-year-long regime of Porfirio Díaz, known as "El Porfiriato".
  • Bohr

    He expanded upon his teacher Ernst Rutherford’s idea, Bohr stated that electrons stay in “clouds” and the farther away you get from the nucleus the more electrons these clouds can hold and the outer ones are what distinguishes the atoms chemical properties and when electrons jump form an outer orbit to an inner one light is emitted.
  • World War I

    World War I
    Austria delivered a note to the Serbia government that, if agreed to, would have almost ended Serbian independence. This ultimatum included ten points. The Serbs only completely rejected one of the points, which called for Austrian officials to take part in the Serbian investigations into the assassination. The official reason was that this wasn't allowed by the Serbian constitution but there was also a fear that the links between some in the government and the assassins might be uncovered.
  • Heisenberg

    Heisenberg created the uncertainty principle in 1925 that states the more precisely the position of a particle is determined, the less precisely the momentum is known in this instant, and vice versa.
  • Chadwick

    He discovered a new subatomic particle that he named the neutron. They have no charge and their function is to stabilize the nucleus of an atom by allowing protons to be close to one another. He discovered them by observing when Beryllium was hit with alpha particles it emitted a strange light and the substance that was emitting the light had no charge.
  • World War II

    World War II
    The primary combatants were the Axis nations of Nazi Germany, Fascist Italy, Imperial Japan, and the Allied nations, Great Britain (and its Commonwealth nations), the Soviet Union, and the United States. Seven days after the suicide of Adolf Hitler, Germany unconditionally surrendered on May 7, 1945. The Japanese would go on to fight for nearly four more months until their surrender on September 2, which was brought on by the U.S. dropping atomic bombs on Nagasaki and Hiroshima, Japan.