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What exactly happens when an electron gains energy?

  1. Apr 1, 2013 #1
    Ok, so I know that the 1p orbital is at a slightly higher energy state than the 1s orbital. And if an electron gets excited it can be promoted from the 1s to the 1p orbital. But what exactly is happening to the electron? How does it "store" the energy?

    Since the s and p electrons overlap at some areas, the electron does not necessarily move away from the nucleus, does it? I mean an orbital is just the probability space of finding an electron, right? So switching from s to p, doesn't that just mean the probability of finding the electron was the spherical area, now it is the dumbbell space. How is this gaining energy?

    I hope this makes sense. Or am I just completely wrong? :/
     
  2. jcsd
  3. Apr 1, 2013 #2

    mfb

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    How does earth "store" energy?
    I don't think this question has a meaningful answer (apart from the description as kinetic and potential energy), but if you find one, you can use it for the electron as well.
    On average (in the expectation value), there can be a shift.

    What is a 1p orbital, by the way? Do you mean 2p?
     
  4. Apr 1, 2013 #3
    Yeah I meant 2s and 2p lol ^^'
    I just want to know what difference there is between an electron with low energy and high energy. It's not like it's moving faster..
     
  5. Apr 1, 2013 #4

    mfb

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    In general, the expectation value of the potential energy is different. If you look for energy levels which just differ by the fine-structure, relativistic effects instead of the potential energy might lead to the difference.
     
  6. Apr 1, 2013 #5
    In general, the higher energy orbitals ARE further from the nucleus on average, think 2s, 3s, and 4s versus 1s. The lowest energy, or ground, state of an electron in a hydrogen atom is the 1s orbital, and that energy is -13.6 eV. This is where the electron "wants" to be. Energy is added to the atom though the absorption of photons which "bump" the electron into higher energy states/orbitals which are, in general with trivial exceptions, further from the nucleus. Think of the energy it takes you to swing a ball on the end of a rope in a circle with a rope length/radius of one meter. Now think of doing the same with a rope length of 3 meters. It's gonna take more energy to maintain that orbit with the 3 meter rope. To make the analogy consistent with your understanding of orbitals and probablilities, the radius of the 3 meter rope can vary depending on where the electron is within the orbital, but on the average the length of the rope is longer than in lower energy state orbitals. As you drive more energry into the system, the energy state of the electron moves through all the orbitals from -13.6 eV approaching 0 eV, at which point the electron is ejected, or ionized, from the atom. This is equivelant of swinging the rope so violently that the ball comes lose and flys off.

    I wouldn't publish that analogy but I think its addresses the conceptual aspect of your question.
     
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