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Energy levels and line spectra

  1. Jul 9, 2010 #1
    I read that each line on a line spectra for an element represents an energy level. Hydrogen only has 1 electron which is in the first energy level so why are there so many lines on the H line spectrum?
  2. jcsd
  3. Jul 9, 2010 #2


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    Each line represents the difference in energy between two energy levels.

    The electron isn't always in the first energy level.
  4. Jul 9, 2010 #3
    Why does the H spectrum contain lines that the Na spectrum doesn't have then? I would have thought that Na spectrum would contain everything H has and more because it contains an electron in the exact same energy level as H has in its ground state doesn't it? Also are all the electrons of an atom excited or is it only the valence electrons or what?

    I thought that the electrons of an atom in its ground state will always be in the lowest possible energy level. Do different elements have different energy levels as a result of their differing atomic charge?
  5. Jul 9, 2010 #4


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    Yes different atoms have different energy levels and this is primarily due to the differing amounts of charge in the nucleus.

    Various things can cause an electrons get "excited" out of their ground state, then they can drop back to a lower energy state and release a photon in the process. Some of the common ways that the electrons in an atom can get excited to a higher energy state are,

    1. Collision with another energetic electron, such as in a gas discharge tube.

    2. An incident photon

    3. Incident radiation in the form of either particle or photon. (This of course really includes 1 and 2 above)

    4. Thermal agitation. (why hot things glow).
    Last edited: Jul 9, 2010
  6. Jul 11, 2010 #5
    No, it doesn't. Energy levels in atoms are really, really complicated. Adding an electron doesn't just add another level. For a start, you have to add another proton to the nucleus. Apart from adding charge to the nucleus, you've also added mass. The electron too interacts with the other electrons, causing them to shift level slightly.

    In a molecule it's even more complicated.
  7. Jul 11, 2010 #6


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    There's an infinite number of levels and lines for any atom.

    These levels are the 'same' in the sense that the levels are determined by and identified by certain quantum numbers (n, l, m, s). E.g. the 1s level is (n=1, l=m=0). But they differ in energy, and they differ in their relative energy and internal ordering, depending on the number of electrons, the nuclear charge (and to a tiny extent, the magnetic moment of the nucleus).
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