## Atomic Spectra Post-Module Assessment

H-Atom ($E_{n}=-\frac{hR}{n^{2}}$)

FDeCastro_1B
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### Atomic Spectra Post-Module Assessment

In the hydrogen atomic spectrum, what is the wavelength of light associated with the n = 2 to n = 1 electron transition?

I understand how to go about this question and the equations to use. However, I still end up getting an answer that isn't even one of the options. Can anybody please walk me through this problem?

Chem_Mod
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### Re: Atomic Spectra Post-Module Assessment

You have to use the following equations: $E_{n} = -\frac{hR}{n^{2}}$ , $E=h\nu$, $c = \lambda \nu$

The energy of the photon emitted (which is always positive) is equal to the magnitude of the change in energy of the electron, which is E(final) - E(initial). Remember that n=1 is the final state, not the initial state since the electron is transitioning down from n=2.

You can then combine the two equations for photons to express the wavelength in terms of the energy of the photon, and then solve. Hope this helps.