one of the lines of the balmer series of the hydrogen emission...?

Question

one of the lines of the balmer series of the hydrogen emission spectrum is at 397 nm. what is the principle quantum number for the original energy level for this transition. show all steps in solving this problem

Could someone please help.. I'm not looking for an answer but just a guide. I'm more into how to do this than the answer... my class just learned this stuff today and it's due tomorrow..

Answer 1

This is probably too late for your class, but....

Find the energy of each energy level.
(for hydrogen, E1 = 1312 kJ/mol; E of any other level = En = 1312/n^2)

Find the amount of energy (in kJ/mol) of the 397 nm line.
(E = hf, f = c/ lambda, don't forget to use Avogadro's number)

Match the energy level to the energy of the light.

Good luck !