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Electron orbitals.

  1. Sep 7, 2010 #1
    What do they have to do with heat? What exactly can cause and electron to become exited and what exactly does the particle it comes in contact with do that causes the electron to become ''exited''? The higher the orbitals and electron spins, the shorter the wavelengths of the radiation it emits correct? But WHY do they emit radiation when the move from a high orbital to a lower orbital?
     
  2. jcsd
  3. Sep 7, 2010 #2
    What do they have to do with heat? More heat, more energy of the system, more energy for electrons.

    What exactly can cause and electron to become exited and what exactly does the particle it comes in contact with do that causes the electron to become ''exited''? Typically "excited" is defined loosely as giving something, in this case electrons, more energy. Anything that gives energy to an electron allows it to become excited.

    The higher the orbitals and electron spins, the shorter the wavelengths of the radiation it emits correct? Electrons only have two different ways they can carry spin, so it can't really increase in the sense to which you are referring. Also as you go up in energy levels, the longer the wavelength tends to get from one state to the next. For example going from n=2 to n=1 will be smaller than going from n=3 to n=2 in wavelength.

    But WHY do they emit radiation when the move from a high orbital to a lower orbital? Energy has to go somewhere right? It's emitted as light (which carries energy).
     
  4. Sep 8, 2010 #3

    alxm

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    The electronic energy state is an energetic degree of freedom of an atom/molecule, just like its translation, vibrational and rotational energy states. Which are the components it's usually separated into. (Strictly speaking this separation is false; as these states are not independent of each other) In simplified descriptions heat is described as 'motion', i.e. only the latter three forms of energy. This isn't true in general, it's just that most molecules are completely in their electronic ground state except at very high temperatures, so they're not carrying any part of the thermal energy.
    If it's a photon, its electrical field transfers energy to the electron through the electromagnetic force. If it's a collision between atoms or charged particles, then the electrical field of that charged particle.
    No. First, if you mean spin by 'the higher the electron spins', then that doesn't necessarily correspond to a higher energy state. A higher spin state can correspond to a lower energy state. (E.g. the oxygen molecule, whose ground state is a triplet spin state) If you mean 'angular momentum', then higher angular momentum usually means higher energy, but only compared to a a state with the same principal quantum number. Second, the wavelength of the light emitted depends on which states its transitioning between. A high-energy state doesn't necessarily mean a high-energy transition.
    They don't have to; they can also transfer that energy 'non-radiatively', for instance when two atoms/molecules collide, or turn it into vibrational energy (vibronic coupling). A photon will only be emitted if the two states fulfill certain criteria (selection rules) which allow for photon creation; usually a change in the overall electrical or magnetic moment of the atom/molecule.

    If an electron is in an excited state where selection rules stop it from decaying (a 'forbidden' transition, by which we really mean 'very improbable'), it can stay there for a very long time. Because then it has to wait for a collision, or utilize some other, more uncommon process. Such as creating two photons at once (which has quite different 'rules'), or wait for random vacuum fluctuations to induce an electric or magnetic moment that it can use to decay.
     
    Last edited: Sep 8, 2010
  5. Sep 8, 2010 #4
    In several messages, you have been musing on "electron spin". I think you are misusing the term. "spin" normally refers to the intrinsic angular momentum of the particle, analogous to the earth spinning on its axis. The electron's spin can point in different directions but never changes in total amount. It always must have exactly 1/2 unit.

    Electron orbitals contain "motion" that is, to continue the analogy, like the earth's movement around the sun. But as soon as you want details, the analogy breaks down since you don't have classical motion or position at that scale. Available orbitals have differing amounts of angular momentum, but also many orbitals in one "shell" have the same total angular momentum but arrange it differently.
     
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