1. The problem statement, all variables and given/known data The numbers following are the results of a lab experiment to find the spectral lines of Helium in a gas discharge tube. The lines I got were roughly: 703nm, 660nm, 590nm, 500nm, 490nm, 470nm, 450nm. The question is, what possible electron transitions could the electrons have went though? 2. Relevant equations Energy level of hydrogen like atoms is given by: E= [(-Z^2)(R)]/n^2 3. The attempt at a solution I'm getting some crazy answers like transitions from n=20 to n=5, or n=9 to n=5. Intuitively, this does not seem to be correct, although my intuition is based on the hydrogen atom which has visible lines only at n=x to n=2. So... is this correct?