Atomic Spectra Post Assessment

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

Rose_Malki_3G
Posts: 127
Joined: Wed Sep 30, 2020 10:02 pm

Atomic Spectra Post Assessment

An excited hydrogen atom emits light with a frequency of 1.14x10^14 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

Can someone please walk me through how to do this problem? Because whenever I get an answer using the rubber equation for n it is never a whole number so I know I am doing it wrong

Kaitlyn Hernandez 3I
Posts: 133
Joined: Wed Sep 30, 2020 9:37 pm
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Re: Atomic Spectra Post Assessment

I used this equation:

$v = R(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}})$

Then, I plugged all of the given values in like this:
$1.14x10^{14} Hz =3.29x10^{15}(\frac{1}{n_{1}^{2}}-\frac{1}{4^{2}})$

All you have to do now is isolate $n_{1}$ and solve. When you do, you should get n = 6.

If you want to check your work, plug everything back in to make sure that you get $1.4x10^{14}Hz$ :)

Catie Donohue 2K
Posts: 96
Joined: Wed Sep 30, 2020 9:55 pm

Re: Atomic Spectra Post Assessment

Could someone please walk me through this problem using the deltaE = -hR/n^2-(-hR/n^2) method that he showed in the lecture?

I've used the deltaE=hv equation to solve for the total change in energy, which I got to be 7.55*10^-20 J. I then substituted that into the equation with the necessary constants to solve for n on the far right side of the equation (since we know the n=4 state is the final state and that is being subtracted by the initial state, which we don't know yet).

I got that n=3.285, but I'm not sure where I went wrong.

Sarah Salam 1J
Posts: 55
Joined: Wed Sep 30, 2020 9:31 pm

Re: Atomic Spectra Post Assessment

Catie Donohue 3I wrote:Could someone please walk me through this problem using the deltaE = -hR/n^2-(-hR/n^2) method that he showed in the lecture?

I've used the deltaE=hv equation to solve for the total change in energy, which I got to be 7.55*10^-20 J. I then substituted that into the equation with the necessary constants to solve for n on the far right side of the equation (since we know the n=4 state is the final state and that is being subtracted by the initial state, which we don't know yet).

I got that n=3.285, but I'm not sure where I went wrong.

I'm wondering the same thing too, since I tried to solve this with both equations. Using the other equation I got 6. When I used this one, I got about 5.3. Close to 6, but not close enough. I think it might have something to do with the h, since the rest of the equation is very similar to the other equation I used. Or did I make a calculation error, or something else?

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