## Week 2,3,4 Sapling HW

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

Jason Nguyen_1B
Posts: 51
Joined: Wed Sep 30, 2020 9:34 pm

### Week 2,3,4 Sapling HW

Question: A red line is observed at 656.3 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line. (What is n2 and n1)

I am unsure of how to begin to solve this question. Could someone walk me through the steps of solving this question?

AlbertGu_2C
Posts: 61
Joined: Wed Sep 30, 2020 9:34 pm

### Re: Week 2,3,4 Sapling HW

For this question, you first have to look at the given wavelength, which is 6.563 *10^-7 m (converted from nanometers). Matching this with the numbers given on the EM spectrum tells us that this light is on the wavelength of visible light, which fits in the Balmer series, which means that the light falls down to the n=2 electron level. Using this, you can plug the numbers into the Rydberg equation:

1/(6.563*10^-7) = -(1.0974 x 10^7)(1/(2^2) - 1/(ni^2)
when you solve for ni, it will come out to 3, so n initial is 3 and n final is 2
Hope this helps!

Ellison Gonzales 1H
Posts: 64
Joined: Wed Sep 30, 2020 10:00 pm

### Re: Week 2,3,4 Sapling HW

AlbertGu_3G wrote:For this question, you first have to look at the given wavelength, which is 6.563 *10^-7 m (converted from nanometers). Matching this with the numbers given on the EM spectrum tells us that this light is on the wavelength of visible light, which fits in the Balmer series, which means that the light falls down to the n=2 electron level. Using this, you can plug the numbers into the Rydberg equation:

1/(6.563*10^-7) = -(1.0974 x 10^7)(1/(2^2) - 1/(ni^2)
when you solve for ni, it will come out to 3, so n initial is 3 and n final is 2
Hope this helps!

For the solution in sapling for this question, why do they say that R= 3.29 * 10^15 Hz but you used a different number for R? Does R equal different amounts during different situations? Also, I was confused as to why you plugged in 1/(6.563*10^-7) for frequency because I thought that was the wavelength. Sorry for the several questions, just stumped on this one

AlbertGu_2C
Posts: 61
Joined: Wed Sep 30, 2020 9:34 pm

### Re: Week 2,3,4 Sapling HW

I haven't seen chem community in a while, sorry about that! To answer your question if you still need it, I used a different variable of the Rydberg equation that uses a different R constant. So if you wanted to do the question using the equation that he gives us you would have to find out the frequency using the given wavelength. Hope this helps! Sorry about the late answer.

Grace_Remphrey_2J
Posts: 60
Joined: Wed Sep 30, 2020 9:54 pm

### Re: Week 2,3,4 Sapling HW

If you still need some help, I would recommend using the value of R that Dr. Lavelle includes on his formula sheet: 3.28984*10^15 Hz. Hope this helped!

Ellison Gonzales 1H
Posts: 64
Joined: Wed Sep 30, 2020 10:00 pm

### Re: Week 2,3,4 Sapling HW

Thank you, Albert and Grace! I now understand that there are different techniques to solving this problem and that the constant R can change if you choose to use a different unit for it, thank you!