Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Bohr's model question

  1. Jun 8, 2007 #1
    hi all,
    quick question with regards to bohr's model

    From what energy level did an electron fall if it emits a photon of 9.38 x 10^-8 wavelength when it reaches fround state within a hydrogen atom?


    this is a textbook question so i know the answer is n = 6


    attached is a copy of my work, please let me know where i'm going wrong.
     

    Attached Files:

  2. jcsd
  3. Jun 8, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    You are mixing up n_i and n_f. n_f is the final level, which in this case is the ground state (what does n_f equal?). n_i, the initial level, is what you are trying to find.
     
  4. Jun 8, 2007 #3
    oh ok umm is there anywhere that i should know what n_f does equal. does the hydrogen part give a clue or ?
     
  5. Jun 8, 2007 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Ground state is the clue! What's the number of the lowest energy level in the Bohr model?
     
  6. Jun 8, 2007 #5

    Doc Al

    User Avatar

    Staff: Mentor

    I assume that should have said "when it reaches the ground state". Right?
     
  7. Jun 8, 2007 #6
    ok heres where i'm not as of now. did i make an error in one or more of the steps?
     

    Attached Files:

  8. Jun 8, 2007 #7

    Doc Al

    User Avatar

    Staff: Mentor

    Yes, you made an error. n_f is an integer, not an energy. What's the orbital number of the lowest energy orbit? (Open the book! :wink:)
     
  9. Jun 8, 2007 #8
    its not 1?
     
  10. Jun 8, 2007 #9
    In atoms with a single electron (essentially the hydrogen atom), the energy of an orbital (and, consequently, of any electrons in the orbital) is determined exclusively by n. The n = 1 orbital has the lowest possible energy in the atom.
    from wikipedia
     
  11. Jun 8, 2007 #10

    Doc Al

    User Avatar

    Staff: Mentor

    Of course it is.

    I hope you have a textbook to use and not just Wiki.
     
  12. Jun 8, 2007 #11
    well replacing that into the equation i have i still get a way off answer?
     
  13. Jun 8, 2007 #12
    oh nevermind! awesome thankyou so much for the help Doc
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook