Atomic Theory History

  • 460

    The Democritean Atom

    Democritus distinguishes all atoms from each other with different size, shape, and color. He discovered this by looking at pictures once used by other scientists. His hypothesis was that each element of Earth had different features. For instance, air particles would be light while salt particles were sharp. He found this out in Abdera, Thrace.
  • Period: 460 to

    The History of the Atom

    Explore the wonderful history of the atom and it changed all over the world!!!
  • Dec 6, 600

    The Five Elements

    Democritus' theory was shrugged off by many philospers, including Aristotle. Aristotle believed that 5 elements are what make up the world: Water, Fire, Earth, Air, and Aether. Water was seen as wet and cold. Fire was seen as hot and dry. Earth was dry and cold, while Air was hot and wet. Aether was neither hot, cold, wet, nor dry. It was seen as The Heavens.
  • Dalton's Theory

    As a secretary of Manchester Litery and Philosophical Society, John Dalton wrote "Experimental Essays" on mixed gases. In the essay, he talks about atomic weights namely hydrogen, oxygen, nitrogen, carbon, sulfur and phosphorus. His points are:
    1. Elements are made of particles called atoms.
    2. Atoms are the same in one element, but are different in another element.
    3. They can't be divided, created, or destroyed.
    4. Atoms can make compounds IF and ONLY IF they combine with another atom.
  • The Electron and its discovery

    At the time, scientists were trying to figure out a fundamental unit. J.J. Thomson found out, in his lab, by using cathode rays , a wheel, and a magnet. When he turned the machine on, the wheel turned, indicating that the electrons had matter. With the magnet, he discovered that electrons had a negative reaction.
  • Alpha and Beta rays

    Rutherford remains the only science Nobel Prize winner to have performed his most famous work after receiving the prize[11]. Along with Hans Geiger and Ernest Marsden in 1909 he carried out the Geiger–Marsden experiment, which demonstrated the nuclear nature of atoms. Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles with very high deflection angles, of a type not expected from any theory of matter at that time.
  • CHARRRGGGEEE!!!of the Electon

    While working as a professor of University of Chicago, Millikan worked on a oil-drop experiment to determine the charge of an electron. Therefore, if one of these two values were to be discovered, the other could easily be calculated. Millikan with help from then graduate student Harvey Fletcher ended up discovering the charge of the electron, which lent to the subsequent attainment of the electron's mass by manipulating electrical charges and magnetic fields.