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Homework Help: Quantum energy level, calcualting total energy

  1. Oct 13, 2009 #1
    1. The problem statement, all variables and given/known data
    The element N has 7 electrons and 7 protons in the atom. An ion of N has all the electrons removed except 1, so it resembles a hydrogen atom with a nuclear charge of +7 e.

    E1(Hydrogen)= -13.6eV, r1(Hydrogen)= 5.29x10^-11m.
    k = 8.99x10^9 e = 1.6x10^-19

    What is the total energy (in eV) of the lowest energy state available to the ion?

    2. Relevant equations

    E = -((k*e^2)/(2r))

    3. The attempt at a solution

    It's been driving me insane! I've put every single combination of variables into the equation, and nothing is coming out correctly. They're all in order of magnitudes wrong, so I think I might be using the wrong constants/variables, or even the wrong equation. Can anyone point me in the right direction, as to what I should be putting where? Thanks!
  2. jcsd
  3. Oct 13, 2009 #2
    Use the equation En=-Z^2*(E0/n^2), where n is the energy level, Z is the number of protons, and E0 is 13.6 eV. I think this will give you the correct answer.
  4. Oct 13, 2009 #3
    Absolutely brilliant. I haven't seen that equation yet, so I'll have to look it up to understand it, but it sure as heck works! Thanks for your time, hugely appreciated.
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