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Electron Phasepositive and negative?

  1. Jul 12, 2009 #1
    EDIT: This may be better in the Chemistry forum, I'm really not sure.

    I'm just doing some basic qualitative MO theory for my first year chemistry class, and i am becoming quite confused.

    My text says shows your typical 'dumbbell' model of a p orbital, each a different colour, and states "The two lobes of the p orbitals are of opposite phase."...without actually explaining what phase is.

    Is phase just another name for it's orientation along an x y z axis, or does it have to do with the magnetic moment?
  2. jcsd
  3. Jul 13, 2009 #2
    In the "dumbbell" model of the p orbital, the size and shape of lobe is related to the probability of finding the electron at that angular location. It's a bit more complicated, because, strictly speaking, the value at any given point on the surface is actually a complex number, where the phase refers to the complex phase at that point. The dumbell surface actually represents the angular part of the wave function describing the electron in that orbital, which is a complex number in general.

    If you start at some point on one lobe, and rotate around by 180 degrees such that you're on the other lobe, this new point will have opposite sign from the point you started at.

    If you're familiar with the idea of phase shifts when talking about sine and cosine functions, then you can see how a shift of 180 degrees causes the point to flip sign. It's kinda like that in this case.
  4. Jul 15, 2009 #3
    ah, so it's purely a spatial thing. Thanks, I think I get it now.
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