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Electron crash into Proton

  1. Mar 2, 2005 #1
    Why doesn’t the Electron crash into the proton??
    We know in an H atom the e- is attracted to the + charge of the proton.
    And it wants to get down to the "0 level" orbit.
    But what makes that level zero – or why does e- stop going down?
    Is there another force that counteracts the force of charge trying to pull them together?
     
  2. jcsd
  3. Mar 2, 2005 #2

    dextercioby

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    There are a few things first:a proton and an electron are treated in QM as point particles...Choosing the system of coordinates with the center in the point in which the proton (assumed for simplicity to have an oO mass (if not,the problem doesn't suffer too much)) is found,your situation would require that the electron's position vector/coordinates coincide with the proton's...
    QM-al analysis of the H atom proves that the probability density for the electron to be in the origin is ZERO...

    A very good (not perfect,however) description is given in "QM" of A.Messiah and an even better in H.A.Bethe and Salpeter:"Quantum Mechanics of One andTwo-electron atoms"​

    Daniel.
     
  4. Mar 2, 2005 #3
    OK I think I can see how a QM formula can define that an Electron shall never be where a proton is. But is there something in it, or any theory, that tries to explain why it stays away at the distance it does?

    How does e- figure out where the zero level is, and stop at that distance from the proton?
     
  5. Mar 2, 2005 #4

    dextercioby

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    Nope,the electron never stops...He's everywhere.He's not really ubiquous,but the proability of fuinding it in a certain volume everywhere in space is nonzero...As for "zero level",that's linked to the quantization of his energy (bound states-discrete spectrum)...BTW,if the H atom is isolated (doesn't interact with anything),he's in a stationary state,the fundamental one,in which all observables are time independent...Basically,it's a static picture,when it comes to observables,but NOT to states (Schroedinger picture).

    QM has answers for all your questions regarding atom world.

    Daniel.

    P.S.There's a lot more to it,basically a whole book.Things cannot be explained in forum posts in great detail,just generalities,sorry.
     
  6. Mar 2, 2005 #5
    Anybody every see any theory other than QM even try to explain this?
     
  7. Mar 2, 2005 #6

    dextercioby

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    Nope.Reletivistic quantum mechanics (Dirac's theory) makes improvements of the H-atom's model of Schrödinger.That's still QM.Quantum electrodynamics makes improvements to Dirac's theory,but essentially Qed is still built from the framework of QM...

    Daniel.
     
  8. Mar 2, 2005 #7
    How about any ideas not related to quantum mechanics at all,
    Has anybody else ever heard of anyone even caring that this seems like something unaccounted for and unexplained?
     
  9. Mar 3, 2005 #8

    dextercioby

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    Nope.There are no other fundamental theories.Condensed matter is properly described using QM and QFT.


    Daniel.
     
  10. Mar 3, 2005 #9

    jtbell

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    People tried to do this for years (roughly 1900-1925) before quantum mechanics came along, and I'm sure some people continued to try to do it for a while afterwards. Nobody was able to do it adequately, which is why physicists accepted QM when Schrödinger, Heisenberg et al. developed it, even though it has many strange features.
     
  11. Mar 3, 2005 #10

    jtbell

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    While I'm thinking about this... in heavier atoms, with a nucleus of non-negligible size, there is a small but finite probability for an electron to be inside the nucleus. When this happens, in certain nuclei, the electron can combine with a proton to convert it to a neutron and release a neutrino. This is one of the ways that unstable nuclei decay. Logically enough, it's called electron capture.

    This happens only in cases where the new nucleus has a smaller mass than the old nucleus. The mass difference is "converted" into the energy of the neutrino. With hydrogen, it's not possible because the mass of a single neutron is larger than the mass of a single proton.
     
  12. Mar 3, 2005 #11
    although it is always correct for the electron, let me add that this is not always the case for the proton. The proton is very much like a small ball 1fm diamater. There are ways to take that into account when one probes such distances within the framework of QM. Yet in that case, one is forced to use relativistic QM, because when the point-like approximation fails it implies that the electron has to be ultrarelativistic.
     
  13. Mar 4, 2005 #12
    It's the same kind of thing with the planets, with the centripetal force and all. It's kind of the way you'd think the earth might crash into the sun because they're attracted towards each other by gravity but they dont because of centripetal force. Maybe the electrons behave like mini-planets?
     
  14. Mar 4, 2005 #13
    This is not a good way to think about this problem, because the earth would eventually crash into the sun if the lifetime of the sun weren't so short compared to the time it would take the earth to loose enough energy to run into it.
     
  15. Mar 4, 2005 #14
    But how can the earth lose energy if it's in space, There's no friction slowing it down is there?
     
  16. Mar 4, 2005 #15

    dextercioby

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    For about 92 years it has been scientifically proven that electrons DO NOT behave like (very little) planets.

    Danie
     
  17. Mar 4, 2005 #16
    Now I cannot solve it, but I believe the jury is still out on the gravitational "N-body problem" (I don't know if they include gravitational radiation in these calculations or not). If you include inelastic collisions though energy will slowly leave the system.

    But please let us not hijack this thread, if you are interested post in the appropriate forum.
     
    Last edited: Mar 4, 2005
  18. Mar 4, 2005 #17
     
  19. Mar 4, 2005 #18

    dextercioby

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    It is one of the fundamental forces:electromagnetism.In simple QM,we refer to it as "Coulomb potential".

    Daniel.
     
  20. Mar 4, 2005 #19
    But wouldn't that force have the opposite effect since the charges on the electron and proton are different. Would the attraction between positive and negative not just cause the electron to crash into the nucleus? What's keeping the protons and electrons apart?
     
  21. Mar 4, 2005 #20

    dextercioby

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    In the initial Bohr's model,the quantization of energy levels.In the QM model of the atom,simply the model altogether,as a direct application of the axioms...

    Daniel.
     
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