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Homework Help: Wavefunction of a one electron species?

  1. Jan 17, 2010 #1
    1. Compute the ground state energy and first excited state energy of a one electron species with Z = 5.
    E = -(Z^2*e^2)/(8*pi*epsilon 0*a*n^2).

    2. I cannot for the life of me figure out how to find "a."

    3. I know from the question that Z=5 and I assume e=-1.6e-19 C because the pi epsilon 0 thing would go with permittivity constant which allows unit cancellation and n=1 for ground state and n=2 for first excited state. The only problem is I cannot figure out what "a" is so I cannot attempt to answer the question. Help?
  2. jcsd
  3. Jan 17, 2010 #2


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    I'm guessing that by "one electron species," you mean one-electron atoms. If that's the case, [itex]a[/itex] probably stands for the Bohr radius. You should be able to find its definition in your textbook or notes.
  4. Jan 17, 2010 #3
    That makes sense because I saw something about that when I was using google and wikipedia to try to figure it out but the problem is this class doesn't have a textbook and we haven't had notes because we have only met once. Can you help me figure out how to find the Bohr's radius?
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