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Motivations for plum pudding model (advanced)

  1. Jul 17, 2011 #1

    Is anyone able to direct me to information regarding the motivation of the plum pudding model of the atom (as opposed to a simply a collection of positive and negative charges)?

    I am looking for an explaination at the advanced undergrad + level. I recall once reading an explaination in an introductory book, but forgetting it because I was able to recognise that it was a bogus exposition.
  2. jcsd
  3. Jul 17, 2011 #2
  4. Jul 18, 2011 #3


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    Your best bet is to try to find a biography of J.J. Thomson somewhere. Or at least an historical account of his cathode ray experiments. I know he formatted his hypothesis of the plum pudding model based on the results of those experiments, but I don't know much beyond what you can easily find on wikipedia and elsewhere.
  5. Jul 21, 2011 #4
    There is a link on the bottom of the wikipedia page to an excerpt of Thomson's original paper. I have found the whole paper here :


    In it, Thomson seems to show that if the electrons are restriceted to move in various planes whose centers are the center of a uniformly charged shpere, they will find their equilibrium in concentric rings in those various planes.

    I cannot infer why he would use a uniform sphere of positive charge rather than a point charge though, other than that he anticipated the former would provide better test implications (about the chemical properties of various atoms, for instance). I may have to wait until I get back to my university to continue investigating, if I have time.
    Last edited by a moderator: Apr 26, 2017
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