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Bohr model and quantum model

  1. Jan 17, 2014 #1
    Please excuse for my less knowledge in the subject.But I have genuine inquisitiveness.
    My Question is:
    If we assume electrons travelling in the orbit around nucleus like planets by inverse square law then electron must always be in the plannar path i,e. never coming out of plane of motion.Then how this model was accepted to account for the ball like look of atom in pre quantum physics.
     
  2. jcsd
  3. Jan 17, 2014 #2

    mathman

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    It is hard to answer a question where the physics is completely wrong. The planetary model just doesn't hold. Electrons in atoms are described by quantum states, without any particular location.
     
  4. Jan 17, 2014 #3
    Thank you mathman.I want to know from historical perspective.
     
  5. Jan 18, 2014 #4

    mathman

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    Google "model of atom". You will get lots of historical information.
     
  6. Jan 18, 2014 #5
    Thank You mathman!
     
  7. Jan 18, 2014 #6

    ChrisVer

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    Well, the physics are not totally wrong I guess...
    What you say, corresponds to the conservation of angular momentum, and of course finds practice even in Quantum Mechanics. What Quantum Mechanics did was in fact to "cancel out" the image we had of trajectories, but the mean values follow classical laws (so as mean values the classical theories that were built still hold- angular momenta are conserved, the Runge-Lenz vector still exists etc). Of course the basic ideas are totally different.

    In fact I don't think they ever considered the electron moving on a sphere I guess... they considered it moving on fixed orbits... Checking Sommerfield's atomic model can help you get an intuition....
     
  8. Jan 18, 2014 #7
    Thank You ChrisVer!
     
  9. Jan 18, 2014 #8
    Does "locality violation "occur due to not being able to tell anything about the path of electron(which we are accustomed to think in classical sense).Path tells the history of particle I think, as continuous curve one can imagine and at any one particular moment of history one can locate the electron.Then how also in quantum sense(Uncertainty Principle obeyed) does particle reach any where around the nucleus I mean disobeys planar motion.Does it not follow strictly inverse square law?
     
  10. Jan 18, 2014 #9

    edguy99

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    The two main problems that quantum mechanics tried to deal with regarding orbiting electrons.
    1. Why don't orbiting electrons emit radiation since they would be constantly changing direction? and
    2. How does bonding work if the electron is flying around all over the place in orbits?
    In quantum mechanics you see electrons confined to small areas depending on the layout of other protons and electrons. The electron then has a specific probability of being in a particular spot, but normally is assumed to be somewhere within its designated area or "orbital"

    This picture shows some historical ways of displaying electrons, I think #3 is the most common these days.

    electron_models1.jpg
     
  11. Jan 18, 2014 #10

    ChrisVer

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    I'm not sure about what you ask with "locality violation". If you mean EPR paradox and stuff, not quiet right. Their problem is that particles would have to know the state particles at each moment while they are separated in large distances.

    What do you also mean by disobeying planar motion? The thing is that you stopped talking about the "particles" position, but began thinking of possible positions of the particle-probabilities, and they are subject to the potential 1/r (seeing Schrondiger equation). The solution of that answers it.

    Another way, is again the interpretations given by QED, but I'll keep it out at the moment.
     
  12. Jan 19, 2014 #11
    Thank You edguy and ChrisVer! I will join back after some pondering.
     
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