spectral lines

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spectral lines

Postby 505612629 » Sun Nov 01, 2020 2:00 pm

When solving for wavelength of emitted electromagnetic radiation, does the initial n level go as n1 or n2 in the equation "R*(1/n^2"1"-1/n^2"2")?

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Re: spectral lines

Postby Arti_Patel_3H » Sun Nov 01, 2020 2:04 pm

It depends on whether light was emitted or absorbed. If absorbed, n1 (initial) would be a lower number than n2 (final). If emitted, n1 would be a greater number than n2.

Nicole Attiq 3D
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Re: spectral lines

Postby Nicole Attiq 3D » Sun Nov 01, 2020 2:08 pm

A good tip that my TA told me is to always put the bigger number first when using Rydberg's equation since you will always need to get a positive value. For example, if you know n=1 and the electron jumped up some energy levels, you should put (1/1^2) first since you know whatever the value of n final is will be smaller than 1. Hope that makes sense!

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Re: spectral lines

Postby LarisaAssadourian2K » Sun Nov 01, 2020 5:24 pm

I agree with the other responses. Whichever n is a smaller number should be n1 and the larger n should be n2 so that when you plug it into the equation and subtract the inverses of both of them, you end up with a positive number. It will just be easier for you that way.

Pranav Daggubati 3C
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Re: spectral lines

Postby Pranav Daggubati 3C » Sun Nov 01, 2020 5:33 pm

for emission, n1 is usually the smaller one because that results in a bigger fraction, which makes the whole thing positive

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Re: spectral lines

Postby Ava_Basileo_2J » Sun Nov 01, 2020 5:34 pm

Your equation seems to be indicating that the electron is going from n=2 to n=1, because the equation is set up so that "Change in energy = final energy - initial energy". Also, it's helpful to remember that when the electron goes up an orbital the electron is absorbing energy and when it is going down an electron it is emitting energy (negative).

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Re: spectral lines

Postby AlbertGu_2C » Sun Nov 01, 2020 6:01 pm

It would depend on the direction relative to which the electron moved up and down the energy levels.

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