1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is the value of ni for an electron

  1. Apr 10, 2017 #1
    1. The problem statement, all variables and given/known data

    what is the value of ni for an electron that emits a photon of wavelength 93.14 nm when it returns to the ground state in the hydrogen atom

    2. Relevant equations

    planck's constant 6.63 x 10^-34
    3. The attempt at a solution
    no idea
     
  2. jcsd
  3. Apr 10, 2017 #2

    gneill

    User Avatar

    Staff: Mentor

    Hi cindy1234,

    You need to provide some attempt before help can be given. Start by looking though your course notes and text to find relevant equations pertaining to hydrogen emission lines, wavelength and energy, and so forth.
     
  4. Apr 10, 2017 #3
    this is as far as i can get still don't get some of this

    change 93.14 nm to meters
    93.14 x 1 x 10^-9 = 9.314 x 10^-8

    9.314 x 10^-8 = 1.097 x 10^7 rydberg constant

    1 - 1 / n exponent 2 subscript 2 = 0.9787 (how did they get this)
     
  5. Apr 10, 2017 #4

    gneill

    User Avatar

    Staff: Mentor

    There's a particular formula that applies here that should be in your notes or text. It's probably in the chapter that introduces quantum theory as it pertains to atoms and light emission/absorption. Hint: the constant that you named above is used in the formula of the same name.
     
  6. Apr 10, 2017 #5
    chemistry text - has only one example of an electron transition - that is calculate the wavelength in nm of the photon emitted when an electron transitions from the n = 4 state to the n = 2 state in a hydrogen atom - which i can do but i don't know how to change this to get the n subscript i

    tried changing to m and 1 / 9.314 x 10^-8 and get 1.074 x 10^7 as an answer

    found the following on the internet
    wavelength = 430 nm
    find n i
    (1/n 1 ^2 - 1 / n 2 ^2) = 2325581 / (1.09677581 x 10^7)
    (1/2^2 - 1/n2^2) = 0.212038
    1/n2^2 = 0.25 - 0.212038
    n2^2 = 26.342 (only part i don't understand) (only need help with this part)
    n^2 = 5 (square root)
     
    Last edited: Apr 10, 2017
  7. Apr 10, 2017 #6

    gneill

    User Avatar

    Staff: Mentor

    Concentrate on finding the value for the ##n_i## rather than its subscript. You know the sequence of integers that the n's are drawn from, so you can later match the value of n to a subscript.
    They started with the Rydberg formula (which your chemistry text should have). Your problem statement states that the electron transitions to the ground state, giving you one of the n values. The other n value is then the unknown that you're looking for.

    Note that you can use the x2 and x2 buttons in the edit window top bar menu to create subscripts and superscripts for your formulas.
     
  8. Apr 10, 2017 #7

    gneill

    User Avatar

    Staff: Mentor

    Both sides were inverted:

    (1/n2^2)-1 = (0.25 - 0.212038)-1
    n2^2 = (0.037962)-1
    n2^2 = 26.342
    n2 = √26.342
    n2 ≈ 5
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: What is the value of ni for an electron
Loading...