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Single Electron Ions

  1. Oct 25, 2010 #1
    1. The problem statement, all variables and given/known data
    In a hot star, a multiply ionized atom with a single remaining electron produces a series of spectral lines as described by the Bohr model. The series corresponds to electronic transitions that terminate in the same final state. The longest and shortest wavelengths of the series are 63.3 nm and 22.8 nm, respectively. a.) What is the ion? b.) Find the wavelengths of the next three spectral lines nearest to the line of longest wavelength.


    2. Relevant equations
    En = -13.6 Z2/n2
    1/ [tex]\lambda[/tex] = R((1/nf2) - (1/no2))

    3. The attempt at a solution
    To be honest, I'm not even sure where to start. I did try finding nf for the shortest wavelength assuming that the electron started at n = infinity, but it gave a decimal value. The only other thing I can think of is somehow assuming the n in the first equation and the nf in the second are equivalent.
     
  2. jcsd
  3. Oct 26, 2010 #2

    Borek

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    Staff: Mentor

    What do you mean "it gave a decimal value"?

    Second equation you are using is probably wrong - depends on what R value you are using. I guess you used R for hydrogen atom.
     
  4. Oct 26, 2010 #3
    I got an answer for nf which was something like .50034, which I know can't be right since it has to be an integer.

    I used R = 1.097 * 10-7. I don't know how I'd find it for the ion I have especially since I don't even know what it is. My professor also said the only unknowns should be Z and nf.
     
  5. Oct 26, 2010 #4

    Borek

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    Staff: Mentor

  6. Oct 26, 2010 #5
    Okay. I'm using the new equation but for some reason when I try to solve all the variables end up canceling somehow.

    I'm assuming that the longest and shortest wavelengths correspond to shifts from no = [tex]\infty[/tex] to nf and no = nf + 1 to nf respectively. Is that valid?
     
  7. Oct 27, 2010 #6

    Borek

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    Staff: Mentor

    Probably yes.

    [itex]n_\infty[/itex] wavelength should let you calculate final state - just solve for nf, as

    [tex]\frac 1 {n_\infty}[/tex]

    is 0.
     
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