Atomic Spectra: Balmer & Lyman Series (energy levels)

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Shirley Liu 2I
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Joined: Fri Sep 28, 2018 12:16 am

Atomic Spectra: Balmer & Lyman Series (energy levels)

Postby Shirley Liu 2I » Fri Oct 12, 2018 5:37 pm

In the equation V=R(1/(n1)^2 - 1/(n2)^2), is n1 always the lower of the two energy levels? Is this because having a larger n2 would make the R(1/(n1)^2 - 1/(n2)^2) negative and subsequently V a negative value as well, and there is no negative value that corresponds to the atomic spectra?

David S
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Joined: Fri Sep 28, 2018 12:15 am

Re: Atomic Spectra: Balmer & Lyman Series (energy levels)

Postby David S » Sat Oct 13, 2018 1:26 pm

n_1 refers to the initial energy level of the electron, and n_2 refers to the final energy level of the electron. n_1 may be higher or lower than n_2. The negative sign vs positive sign doesn't matter in this case because we are solving for the frequency of the light emitted/absorbed. The signs only matter when we are trying to determine whether the electron gained or lost energy (delta E positive vs delta E negative).

Leslie Cheng 4B
Posts: 35
Joined: Fri Sep 28, 2018 12:29 am

Re: Atomic Spectra: Balmer & Lyman Series (energy levels)

Postby Leslie Cheng 4B » Sat Oct 13, 2018 1:30 pm

Yes, I believe so. The textbook even says that for the Lyman series n1 is always 1, and n2 is 2,3, etc, whereas for the Balmer series n1 is always 2, and n2 is 3,4,etc.
I think the method Dr. Lavelle outlined in lecture, calculating each individual energy level using the equation En = -hR/n^2, then figuring out the difference is a more foolproof method because you know that deltaE=energy final-energy initial and there would be no mixups about which energy level comes first.


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