## Atomic Spectra/Rydberg Formula for Hydrogen

Alex Nguyen 3I
Posts: 100
Joined: Fri Sep 25, 2015 3:00 am

### Atomic Spectra/Rydberg Formula for Hydrogen

Can someone explain why the negative sign is a part of the Rydberg Formula again. I think the formula calculates the energy of an electron at a certain level. So why does a negative change result from a lower to higher energy level? I thought that the electron absorbs energy. Conversely, why is the value positive when an electron moves from a higher to lower energy level? I thought the electron releases energy.

Chem_Mod
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### Re: Atomic Spectra/Rydberg Formula for Hydrogen

As discussed in class we use the more fundamental equation $E = \frac{-hR}{n^{^2}}$ as it gives a much better understanding of the concepts involving electron transitions in the H-atom and the absorption and emission of photons.

Andrew Than 3J
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Joined: Fri Sep 25, 2015 3:00 am

### Re: Atomic Spectra/Rydberg Formula for Hydrogen

When using the Rydberg Formula, keep in consideration that you are using E(final)-E(Initial). The negative sign is merely an indication of the direction, it all depends on if you set it up as the Final-Initial or Initial-Final.
Refer to the course reader and the worked example in there. As said in the above post, refer to that fundamental equation to get the Energy for the Final and Initial state of the electron and then subtract the Final-Initial. You should get a negative number if the energy level is decreasing and a positive number if the energy level is increasing.
I'm not quite sure as to how you are getting a negative change from a lower energy to higher energy level and vice versa.

Alex Nguyen 3I
Posts: 100
Joined: Fri Sep 25, 2015 3:00 am

### Re: Atomic Spectra/Rydberg Formula for Hydrogen

I actually incorrectly stated "Rydberg Formula" in the place of the fundamental equation $E=\frac{-hR}{n^{2}}$. I overlooked the placement of the final and initial E levels. It makes much more sense now. Thank you for the replies.