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### Atomic Spectra Post Module #42

Posted: **Tue Oct 17, 2017 9:09 pm**

by **Abigail Urbina 1K**

Can someone help me with how to solve this problem? The question reads, "An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?"

### Re: Atomic Spectra Post Module #42

Posted: **Tue Oct 17, 2017 9:24 pm**

by **Sarah_Stay_1D**

Abigail Urbina 3H wrote:Can someone help me with how to solve this problem? The question reads, "An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?"

To solve this problem you need to use the formula E=-hR/n^2. So to begin you need to plug 4 into this equation, and you will get the E (final). Next you need the formula (delta)E= E(final) - E(initial). You will also plug 1.14 x 10^14 Hz into the equation E=hv, to get (delta)E. Now you should have all the values except for n^2, so just use algebra to get n.

### Re: Atomic Spectra Post Module #42

Posted: **Wed Oct 18, 2017 11:19 pm**

by **Catherine Yang 3G**

The equation for the change in energy is -hR/n^2 final minus -hR/n^2 initial.

You know the value of h, R, and n final (which is 4), and you can solve for the energy of the photon with the equation E=hv since you are given the frequency. Then there will only be one variable to solve for, n initial.

### Re: Atomic Spectra Post Module #42

Posted: **Thu Oct 19, 2017 1:21 am**

by **Gurshaan Nagra 2F**

Can someone show their step by step process please? I was using the same method as the one in the second reply but kept getting a really wacky answer.