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Homework Help: Discovering the nucleus

  1. May 27, 2008 #1


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    In 1997 we celebrated the centenary of JJ Thomson’s discovery of the electron. Thomson pictured the atom as being like a currant bun, with electron ‘currants’ embedded in a positively charged ‘bun’. Give a short account of three ways in which our model of matter on a subatomic scale has changed since Thomson’s discovery. For each, state clearly how the model changed, and write a few sentences outlining one piece of evidence that played a part in bringing about the change.

    My response:
    I've outline the point, but cannot expand on it, can I have help on the detail:
    • Nuclear atom - Alpha scattering: large angles. Incompatible with bun model.
    • Protons and neutrons in nucleus - Chadwick’s experiment: neutral particle of same mass as H.
    • Quarks (existence of) - Deep inelastic scattering: structure within proton.
    • Momentum of electromagnetic radiation - de Broglie theoretical prediction.
    • Antimatter Anderson’s observation of e - like particle with positive charge.
    • Neutrinos - “Missing” energy in beta decay.
  2. jcsd
  3. May 27, 2008 #2


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    Staff Emeritus
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    1. It looks like you just pasted some tidbits about subatomic particles without actually looking to answer the given question,
    2. You need to look up what different models of the atom involve,
    3. There's a clear emphasis on electrons in the question - as there should be for a question on atomic structure - so don't ignore them.
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