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History of the Atom

By 560034726

  • Dalton Model

    Dalton Model
    His experiments used calculated weights of elements, not philosophy of deduction
    - atoms are tiny, invisible particles
    - all atoms of the same element are the same
    - atoms of different elements are different
    - compounds form when elements combine.
    - different compounds may be formed from the same elements in different, but fixed, ratios.
    His theory was not very complex because protons, neutrons, and electrons were not discovered.

  • Crookes Model

    Crookes Model
    He shot cathode rays into a Crookes tube, and looked at how it interacted under certain conditions. He didn't have any theory of the atom, but this discovery led to Thomson's theory of the atom.

  • Becquerel Model

    Becquerel Model
    He used naturally fluorescent elements to study properties of x-rays. His solution was exposed to sun. which led to seeing radiation.

  • Thomson Model

    Thomson Model
    He used a Crookes tube with an electrometer to separate the charge from cathode rays. Thomson showed that cathode rays, or electron rays, were electrically charged. He developed an atomic theory where the negative electrons are scattered around the atom, which has positively charged particles. This is called the plum pudding or raisin bun model.

  • Rutherford Model

    Rutherford Model
    Gold Foil experiment-
    He shot alpha rays at a piece of golden foil, and he expected the atoms to go through, but some bounced off. He thought that maybe there was a nucleus. His model of the atom was called the Planetary atomic model.

  • Bohr Model

    Bohr Model
    He worked in Rutherford’s lab, and contributed to what Rutherford had. Bohr proposed a theory of the hydrogen atom, consisting of a heavy proton in the center surrounded by smaller electrons. The electrons orbited around the nucleus, only certain orbits would occur without radiation, and that light change was due to electrons changing orbit.

  • Electron Cloud Model

    Electron Cloud Model
    No experiment, but there was a mathematical formula to determine where an electron could and couldn't be, and when plotted, looked like a cloud.

  • Chadwick Model

    Chadwick Model
    Chadwick shot a bunch of alpha rays at a beryllium atom, and he found a radiation coming from it. He concluded that there were neutrons in the nucleus.

  • Current Atomic Theory

    Current Atomic Theory
    A nucleus with Protons and Neutrons with a cloud of electrons far from the nucleus.

  • Democritus Theory (~500 BCE)

    Experiment
    deduction; he knew the things on earth were stable- rocks don’t disappear then reappear- and if he cut a piece of gold in half, it was still gold, but he wanted to know how much he could cut before it wasn’t gold anymore. What they discovered
    He believed everything in the universe was composed of atoms, and that there was an infinite amount of atoms. They deduced that when gold was as small as an atom, it was still gold, but if it went any farther, it wouldn’t exist.

  • Citations 1

    "Blue Sphere." Blue Sphere (21149) Picture by ChristianTheMagician, in Album 1728: Geometric Forms - Pxleyes.com. Web. 04 Dec. 2016.
    "Crookes Tube." Wikipedia. Wikimedia Foundation. Web. 04 Dec. 2016.
    "Development of the Atomic Theory." Development of the Atomic Theory. Web. 04 Dec. 2016.
    "The Discovery of Radioactivity." The Discovery of Radioactivity. Web. 04 Dec. 2016.

  • Citations 2

    "Dublin Schools - Lesson : Light Spectra and Evidence for the Bohr Model." Dublin Schools - Lesson : Light Spectra and Evidence for the Bohr Model. Web. 04 Dec. 2016.
    "Electron Cloud Model (Louis De Broglie & Erwin Schrodinge)." Lionsgensci - Electron Cloud Model (Louis De Broglie & Erwin Schrodinge). Web. 04 Dec. 2016.
    "Historical Models of the Atom." Common Sense Science | Atom Models. Web. 04 Dec. 2016.
    "History of the Atom Timeline." Timetoast. Web. 04 Dec. 2016.

  • Citations 3

    "J. J. Thomson." Wikipedia. Wikimedia Foundation. Web. 04 Dec. 2016.
    Kidsneedscience. "Kids Need Science - On This Day, March 1, 1896, Henri Becquerel..." Kids Need Science. 01 Mar. 2014. Web. 04 Dec. 2016.
    "Rutherford Model." Wikipedia. Wikimedia Foundation. Web. 04 Dec. 2016.
    "This Is the Modern Atom Model." The Particle Adventure | What Is Fundamental? | The Modern Atom Model. Web. 04 Dec. 2016.
    "The Thomson Model - Boundless Open Textbook." Boundless. Web. 04 Dec. 2016.