Historical Timeline of Atomic Theory

  • 322


    Aristotle had his own beliefs on the world, such as the greek four element idea, that Fire, Water, Earth, and Air were the main elements in the world. He also believed in an idea we now know is wrong, that if you cut matter in half, you would just end up with a smaller piece of matter.
  • 370


    Democrtius was the first person to propose the theory that there were particles so small they could no longer be broken down any further. He used the term "Atomos" to describe these particles.
    His ideas were unpopular at the time, but were the first step towards Atomic Theory.
  • Period: 400 to

    Atomic History

  • Becher and Stahl

    These Guys created a theory about an imaginary element called phlogiston. This "Developent" seriously impeded scientific progress because no one realized that phlogiston was hocus pocus. It did not exist. However the idea reigned for about 120 years.
  • Joseph Priestly

    Joseph Priestly, under the impression phlogiston existed, discovered Oxygen, and called it "Dephlogisticated Air" because of the way it reacted to fire. He shared his discovery with another early Chemist, Lavoisier. This caused some heated debate between the two, but it is Lavoisier, not Priestly, who is called the father of Chemistry.
  • Antoine Lavoisier

    Mr. Lavoisier was very careful and talented experimenter. He experimented with "Dephlogistonated air" and named it Oxygen, earning himself the ire of Priestly. He proposed the Law Of Conversion Of Mass, which has among other things earned him the title of father of Chemistry. His talent was cut short quite literally by a guillotine in 1794.
  • John Dalton

    John created a law called the law of multiple proportions, which helped create the Atomic Theory. He developed many new and radical concepts which were very beneficial to Chemistry. On another field of Science, he is also credited with discovering Colour blindness, something that he himself had.
  • Joseph Gay-Lussac

    Joseph Gay-Lussac and Amadeo Avogadro were two men who created two different but similiar laws. The first, Josephs, stated that "at the same temperature and pressure, two volumes of hydrogen gas reacted with one volume of oxygen gas to produce two volumes of water (as a gas)."
  • Amadeo Avogadro

    Amadeo Avogadro created a Hypothesis that, when combined with Jospehs work, solved the atmic weight problem. However, the idea wasn't accepted until much later on.
  • Ernst Rutherford

    Ernst Rutherford proposed the idea that we accept today about atoms, which is that the protons, (which he named) were centered in the middle of an atom and electrons orbited them, leaving lots of "Empty Space." He also thought of the idea of neutrons. His work was quite radical that did not work with Newtonian Physics.
  • Francis Aston

    Francis invented the mass spectograph in 1920. He also discovered isotopes. Without the mass spectograph he invented, we would not be able to study atomic masses, and Rutherford may never have discovered neutrons.