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Hard Chem/Physics Question

  1. Sep 29, 2013 #1
    1. The problem statement, all variables and given/known data
    In the equation for the bohr model of the atom, what is the n value for Li2+ ion?


    2. Relevant equations
    E = -2.178 x 10^-18J(z^2/n^2)


    3. The attempt at a solution

    Since it is Li2+ that means it has 1 electron. So z = 1. Now I have an equation with 2 variables (impossible to solve).

    I dont know what E is and I have to find n. Does anyone have any idea on how to do this?
     
  2. jcsd
  3. Sep 29, 2013 #2
    z is the charge of the nucleus and is not 1 for Li.
    For the rest, it may help to post the complete text of the problem.
     
  4. Sep 29, 2013 #3
    It's Li2+ not Li. And this is the complete text of the problem.....
     
  5. Sep 29, 2013 #4
    It does not matter. The charge of the nucleus is 3e for Li, Li+, Li2+.
    So z=3.

    But n can take any value so the question does not seem to make sense.
     
  6. Sep 30, 2013 #5
    IF the question is instead: In the equation for the bohr model of the atom, what is the z value for Li2+ ion?


    Does this make more sense?
     
  7. Sep 30, 2013 #6

    DrClaude

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    Staff: Mentor

    Yes.
     
  8. Sep 30, 2013 #7
    Well isn't there still three unknown variables Energy and n value and z value?
     
  9. Sep 30, 2013 #8

    Borek

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    But you are not asked to find all three, just to tell what (most likely) Z is.

    As worded question doesn't make sense, unless it asks for Z, not n.
     
  10. Sep 30, 2013 #9
    What is Z? What does it mean? What is Z for lithium?
    (yay! 200th post)
     
  11. Sep 30, 2013 #10
    The question exactly as it appears word for word is: In the equation for the Bohr model of the atom, what is the Z value for Li2+ ion?

    I am still unsure of how to go about this question. Which equation should I use?
     
  12. Sep 30, 2013 #11

    DrClaude

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    You had the right equation in the OP. Go back in your notes/textbook and find what the ##Z## stands for.
     
  13. Sep 30, 2013 #12
    it stands for nuclear charge.
     
  14. Sep 30, 2013 #13

    Borek

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    And what is nuclear charge for lithium?
     
  15. Sep 30, 2013 #14
    It is +3. So there is no need to use the equation for this problem? Seems more challenging than that.
     
  16. Sep 30, 2013 #15

    Borek

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    Staff: Mentor

    No, it is as simple as that. You were making it more difficult than it is from the very beginning.
     
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