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Dipolar substances and atoms.

  1. Apr 20, 2014 #1
    Can an atom be considered as an example of a dipole? It has positive charge in the nucleus and negative charge around it?!
  2. jcsd
  3. Apr 20, 2014 #2


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    Depends. For example with neutral hydrogen atom the electron "cloud" completely cancels the positive charge from the nucleus.

    But if there is an external field applied, then the electron cloud can be reshaped so that there is a dipole moment. This happens when sunlight passes by the nitrogen molecules in the atmosphere - the result is Rayleigh scattering of the light from these molecular dipoles - and so the sky appears blue.

    See http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html
  4. Apr 20, 2014 #3
    That means for a neutral Hydrogen atom it is "Yes" but for any other atom, it is no, (unless electric field is applied). Am I right if I say that this is because there is only one electron in a neutral H atom ,as for one electron and one proton, the direction of dipole moment is possible to tell?!
  5. Apr 20, 2014 #4


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    It is a _no_ for the neutral hydrogen atom.

    I must have explained things poorly if you got the other impression. The hydrogen atom, like all other atoms, must be analyzed via quantum mechanics. The "orbital electrons" are not located in a definite place, but instead have definite energy states. They "appear" as smeared out in an "electron cloud" - even when there is only one electron, as with hydrogen.

  6. Apr 20, 2014 #5


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  7. Apr 20, 2014 #6
    Now I got it!
  8. Apr 20, 2014 #7
    Sorry. I know. I was a bit confused on where to post this query at as it comes under atomic physics and general physics, both - that is why I posted it twice. I didnt read the rules carefully- sorry.
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