Atomic model Timeline

  • Dalton's early atomic model

    Dalton's early atomic model
    John Dalton was an English Chemist that came up with one of the earliest atomic models. He purposed that they are indivisible and that there is nothing smaller. He also stated that no two elements share the same atoms but atoms could bind together to form compounds.
  • First Cathrode Tube

    First Cathrode Tube
    Julius Plucker a German mathmatician and phisicist built one of the first Cathrode Ray Tubes (CRT) in 1859.
  • J.J Thomson's Plum Pudding model

    J.J Thomson's Plum Pudding model
    In 1897 Thomson purposed the Plum Pudding model. He also discovered the electron and with this discovery a new theory came up that atoms were made up of small particles. He proved his theory using the cathrode tube.He also made the discovery that atoms are made up of protons, neutrons, and electrons. Proving Dalton's theory wrong that atoms are indivisible because atoms are divisible. He also proved that there are the same amount of electrons as there is protons because the atom is neutral.
  • Hantaro Nagaoka

    Hantaro Nagaoka
    A Japanese physicist by the name of Hantaro Nagaoka suggested that a atom has a central nucleus. Electrons move in orbits like the rings aroud Saturn. He was born on August 15, 1865 in Nagasaki and died on December 11, 1950 in Tokyo. He went to school at Tokyo University. Hantaro Nagaoka was the world’s first scientist to present a Saturnian model of the atom.
  • The oil drop experiment

    The oil drop experiment
    In 1909 Robert Milikan performed the Oil Drop experiment that determined the charge and mass of am atom.
  • Rutherford's Gold Foil Experiment

    Rutherford's Gold Foil Experiment
    In 1911 a physicist named Ernest Rutherford did an experiment experiment called the "Gold Foil Experiment" to test Thomsons Plum Pudding model. He shot high alpha particles and a thin gold goil atom. As he ecpected most alpha particles went through but surprisingly some defelcted backwards. He later came up with his own model which put the protons in the neucleas and had the electrons orbit around like a cloud.
  • Bohrs Atomic Model

    Bohrs Atomic Model
    Niels Bohr tested Rutherford's atomic structure by assuming that electrons travel in orbits. This led to possible energy levels for these orbits and the postulation that the emission of light occurs when an electron moves into a lower energy orbit. This meant electrons can travel to different orbit levels by gaining or losing the right amount of energy. Bohr would then purpose his new model in 1915.
  • Aufbau Principle

    Aufbau Principle
    The aufbau diagram is used to find where the electrons would be found in an orbital. The diagram has to do with electron configuration, and how atoms combine to create solutions. In each slot of the diagram, you would put an "up-spin and down-spin" which is electrons taking up the space of an orbital and energy level. Develpoed by Niel Bohr.
  • Shrodingers equation

    Shrodingers equation
    Ewrin Shrodingers equation was published in 1926. It desctribed the how the quantum state of some physical system changes in time.
  • James Chadwick

    James Chadwick
    James Chadwick was an English physicist who confirmed the existence of neutrons which have no charge. Atomic nuclei have neutrons and positively charged protons. He was awarded with Nobel Prize in Physics, Copley Medal, and Franklin Medal.
  • Chain Reaction

    Chain Reaction
    Enrico Fermi conducted the first controlled chain reaction releasing energy from the atoms nucleus.
  • Atomic Bombing

    Atomic Bombing
    The atomic bombings of the cities of Hiroshima and Nagasaki in Japan was run by the United States during the final stages of World War II in 1945. These two events represent the only use of nuclear weapons in war.
  • Raidocarbon

    The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949