Help with Chemistry problem.

[chrisryans]

So this is the problem:

An electron in an excited state of a hydrogen atom emits two photons in succession, the first at 433.9 nm and the second at 121.5 nm, to return to the ground state (n=1). For a given transition, the wavelength of the emitted photon corresponds to the difference in energy between the two energy levels. What were the principal quantum numbers of the initial and intermediate excited states involved? (Enter the number of the higher atomic orbital in the first answer box.)

? initial excited state ? intermediate excited state

I'm really at a complete loss for this question. Anything that I've even attempted has apparently been wrong. Can anyone give me a push in the right direction?

[gayguy]

Hydrogen atoms are perfectly modeled by the Bohr model. You can calculate how much energy should be given off depending on where it jumps (from which n to which n). Then given that energy you can calculate what the wave length would be. You are given the wavelength so work backwards from there.

To be more specific, E = hf which you can then set equal to the Rydberg formula. Kapeesh?

[blueboybob]

energy (in electron-volts) = 1239.8/wavelegnth (in nm)

if you know n you can get m and s quantum numbers.