According to my teacher, an electron is point sized and it does not absorb or release energy. Moreover, my teacher says their orbital absorbs energy rather than the electron. If that is the case, then what about the photoelectric effect, in which electrons release energy after excitement?


closed as unclear what you're asking by ACuriousMind, John Rennie, Diracology, CuriousOne, honeste_vivere Jul 28 '16 at 12:02

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  • $\begingroup$ An electron both generates and feels an electromagnetic field and through interactions and processes it may of course absorbe or release energy when changing quantum state. Also, there is no such thing as "the orbital", rather there is the wave function associate to the state of the electron (no cloud as in the books). $\endgroup$ – gented Jul 27 '16 at 15:09
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    $\begingroup$ I can't tell what the statement "an electron absorbs or released energy" is supposed to mean - depending on the precise meaning, the statement is true, false, or meaningless. $\endgroup$ – ACuriousMind Jul 27 '16 at 15:10
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    $\begingroup$ Doesn't an electron absorb/release energy in the form of photons as it leaps between energy states? $\endgroup$ – heather Jul 27 '16 at 15:27
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    $\begingroup$ Would a free electron "absorb energy" if it were accelerated by an electric field? $\endgroup$ – M. Enns Jul 27 '16 at 15:50

... an electron is point sized

Here you find what John Rennie says about this:

Although it's commonly said that fundamental particles are point particles you need to be clear what this means. To measure the size of the particle to within some experimental error d requires the use of a probe with a wavelength of λ=d or less i.e. with an energy of greater than around hc/λ. When we say particles are pointlike we mean that no matter how high the energy of your probe, or how small its wavelength, you will never measure a particle radius greater than your experimental limit d. That is the particle will always appear pointlike no matter how precise your experiment is.

But this does not mean that the particles are actually zero dimensional, infinite density, dots whizzing around.


and it does not absorb or release energy

It does absorb and release energy. For example, with a laser it is possible to brake electrons which are moving towards the laser source. The electron slows down and lose kinetic energy, it release energy in the form of emitted photons. After standstill of the electron the laser will accelerate the electron away from the laser source. To hold the sum of all involved energy components during positive acceleration an accelerated electron has to absorb some part of the EM radiation from the laser.

... orbital absorbs energy rather than the electron.

This is negotiable and depends from does one think about electrons as particles or as a disturbance of some field. From the particle view it is without doubt, electrons moving nearer to the nucleus are releasing energy in the form of photons. Getting disturbed by a photon of needed minimum energy the electron absorbs partially the photons energy and is moving away from the nucleus. in the case of a field view the electron orbitals absorb and emit the energy.

  • $\begingroup$ I'm confused doesn't electron seem to be point like because the eigenfunction of the position operator is the dirac delta function (which is point like). $\endgroup$ – drewdles Jul 27 '16 at 18:04
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    $\begingroup$ @AnantSaxena Will two electrons - if they are really point like particles - interact? Throw one electron on an other. If they are point like, they should not interact. And, since they have an electric field, the discussion is obsolet. More interesting is the question, is this field really infinite. $\endgroup$ – HolgerFiedler Jul 27 '16 at 18:21
  • $\begingroup$ my point was the electrons are (I think) zero dimensional (at least upon measurement) due to the argument above which is what I think the professor could have possibly intended to mean. $\endgroup$ – drewdles Jul 27 '16 at 18:29
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    $\begingroup$ "Throw one electron on an other. If they are point like, they should not interact." Is simply wrong. Electrons don't interact because of size thy interact through their charges. $\endgroup$ – dmckee Jul 27 '16 at 19:29
  • $\begingroup$ @dmckee "since they have an electric field, the discussion is obsolet." $\endgroup$ – HolgerFiedler Jul 27 '16 at 20:04

To answer this question, you'd have to agree on what model of the electron you're talking about. Quantum mechanical? Classical?

Electrons can have force exerted on them by electric fields. If this causes the electron to move, then work is done to it. Thus, energy is transfered "to" the electron.


People say the "electron" releases the energy for shorthand, but once again the energy exchanges in the photoelectric effect have to do with photon energy and the electron's orbital energies.

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    $\begingroup$ This is correct, but too short to get an upvote. I invite you discuss this in more depth. $\endgroup$ – garyp Jul 27 '16 at 16:07
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    $\begingroup$ The electrons that participate in the photo-electric effect (at least as the experiment is normally constructed) are mostly in a conduction band associated with the cathode as a whole rather than an orbital associated with a single atom. $\endgroup$ – dmckee Jul 27 '16 at 19:28
  • $\begingroup$ @dmckee true. I clearly have multiple revisions to make for this to be a decent answer $\endgroup$ – Brian B Jul 27 '16 at 19:42
  • $\begingroup$ @dmckee A crystal has a lot in common with a molecule. An example that straddles the descriptions is the conducting polymer. The same principle applies, although the terminology might be different. $\endgroup$ – garyp Jul 27 '16 at 20:47
  • $\begingroup$ @garyp Sure, that's a suggestion for a change of vocabulary rather than a major criticism of the answer which is a bit minimalistic but not wrong in any irreparable sense. $\endgroup$ – dmckee Jul 27 '16 at 22:29

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