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Homework Help: Bohr's atomic model

  1. Feb 2, 2005 #1
    I need help with these 3 questions:
    1. Describe the Bohr model of the atom. How does it differ from a planetary model based on classical physics?
    2. In terms of the Bohr theory why is that electrons don't spiral into the nucleus?
    3. If atomic energy levels were not quantized, but could vary within certain limits, what colud atomic spectra look like?
  2. jcsd
  3. Feb 3, 2005 #2
    In principle questions 1 and 3 would be automatically answered as you read the relevant portions from your physics textbook. For question 2 you need to know a Bohr postulate which explained it. The electron wouldn't spiral into the nucleus unless it lost kinetic energy. So the only we could have a stable rotational condition if the kinetic energy would be constant throught the uniformly circular trajectory. This was explained with the help of Stationary Orbits...in which the electron would rotate without radiating energy. You might think this has something to do with standing waves on a stretched string and you would be right....but I'll leave the reading to you.
  4. Feb 3, 2005 #3
    I re-read question 3 and I have the following short answer, if you mean that the energy levels are continuous. The spectra would be continuous too as energy wouldn't be quantized and so the wavelengths would be continuous functions as well. So you wouldn't be able to recognize discontinuities corresponding to different energy levels in the spectra.
  5. Feb 3, 2005 #4
    Surely I have done the reading, these are the quetions of that chapter.
    I don't get what happend to the classical physics principle, the one that said: a charged mass radiates when it accelerates.

    Did Bohr model reject that principle? Or we still believe in it?

    P.S I'm studing chemistry :)
  6. Feb 3, 2005 #5


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    That principle is totally inaccurate in the atomic (subatomic) world...It's in the realm of MACROSCOPIC PHYSICS,namely classical electrodynamics...

  7. Feb 3, 2005 #6
    Thank you
  8. Feb 10, 2005 #7
    Thats why..................
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