## Energy Levels

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

Posts: 72
Joined: Wed Sep 18, 2019 12:18 am

### Energy Levels

Hi, so I'm super confused on how I'm supposed to find the energy level an electron rises to (or drops to). I know that we are supposed to use the formula that Dr. Lavelle gave us, but I'm not sure how to use it exactly. For example, if I'm trying to find the level a Hydrogen atom rises to, how would I go about that? Thank you!

philipraj_1F
Posts: 52
Joined: Fri Aug 30, 2019 12:16 am

### Re: Energy Levels

You would have to use the Rydberg equation to solve that

Amy Kumar 1I
Posts: 114
Joined: Thu Jul 11, 2019 12:15 am

### Re: Energy Levels

By using (-hR/n^2) for the final n value minus (-hr/n^2) for the initial n value, you can find the energy difference. If the energy difference and one of the n values are known, you can rearrange the equation to find the other n value since -hR is a constant value.

William Francis 2E
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

### Re: Energy Levels

I was confused about that too, but I think I have it figured out now. In many cases, the question will imply where the electron in the hydrogen atom begins or ends. For instance, if ultraviolet light is emitted by the change in energy level, this light can be recognized as part of the Lyman series, indicating that the electron dropped to the the first energy level (n=1). Let's assume that this is the case in a given problem. Since you know that the final energy level is 1 based upon what I just described, you just need to find the initial energy level. To do this, calculate the energy of the ultraviolet light emitted if this is not given. Now, you can use the equation, E=-(hr)/(n^2), to find you n-initial value. The energy of the light emitted must be equal to the energy final minus the energy initial. You know that the energy final must be equal to -(hr)/(1^2) (which can be simplified to (-hr)) since n-final equals one. So... (-hr) minus (-hr)/(n-initial^2) must be equal to the energy of the emitted light. Now, you can solve this equation for n-initial. I hope this helps and that it isn't too confusing!

Tyler Angtuaco 1G
Posts: 130
Joined: Wed Sep 11, 2019 12:16 am

### Re: Energy Levels

Questions will state or hint towards either the initial or final energy level an electron was in. There should also be a way to calculate the total energy the electron absorbed/emitted. Using the Bohr's frequency condition and the Rydberg formula, calculate the energy an electron has in the energy level provided, and the difference between that and the energy absorbed/emitted will be the energy of the energy level you are trying to find. Set that equal to -hR/n^2 and you should be able to find the missing energy level since h and R are constants.