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Physics teacher

  1. Nov 10, 2014 #1
    i only joined to answer a question and now i've joined i find the thread is closed :-(

    the question was:
    An element has an ionization energy of 1.66 × 10-18 J. The three longest wavelengths in its absorption spectrum are 253.7 nm, 185.0 nm and 158.5 nm. Construct an energy-level diagram for this element.

    and my answer is:
    E=hc/λ so E= 6.63 x 10-34 x 3.0 x 108 /λ = 1.989x 10-25/λ
    Eorbital1-Eorbital0=7.84x 10-19 J
    Eorbital2-Eorbital0=1.08x 10-18 J
    Eorbital3-Eorbital0=1.25x 10-18 J

    Eionisation= 1.66 × 10-18J... we make this zero and compare how much energy it would take to get an electron to this energy
    Eorbital1 - Eionisation=7.839968466693x 10-19-1.66 × 10-18=-8.76x 1019 J
    Eorbital2- Eionisation=1.075135135135x 10-18-1.66 × 10-18=-5.85x 10-19 J
    Eorbital3- Eionisation=1.2548895899x 10-18-1.66 × 10-18=-4.05x 10-19 J

    see final answer in attached picture answerQ4.jpg
  2. jcsd
  3. Nov 10, 2014 #2
    Welcome to PF. Can you link me to the closed thread?
  4. Nov 10, 2014 #3
  5. Nov 10, 2014 #4
    I've opened it for you
  6. Nov 10, 2014 #5


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    Staff: Mentor

    Welcome to the PF, shamim.

    Please notice that the thread is from 2009, with no recent activity. So it may be that the person asking for the help has moved on and perhaps graduated by now. :-)

    Also, we do not permit the posting of solutions in the Homework Help forums of the PF. It is great if you provide hints, ask probing questions, find mistakes, etc. But the student must do the bulk of the work on their schoolwork. You can review the PF posting guidelines under the "Info" link at the top of the page.
  7. Nov 10, 2014 #6


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    Staff: Mentor

    And since the student who posted the question hasn't worked on it since 2009, he's not likely to come back to finish it.

    As berkeman said, our policy is that people helping with homework must only do things like give hints, correct mistakes, and confirm correct answers, not provide solutions for the original poster.
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