[kentucky_girl]

Hi all. This is my first time on these boards, and I'm hoping you'll be able to help me out. I'm studying for a quiz I have tomorrow, and I've realized that I missed one on my homework that I didn't notice, and I don't know how to answer it correctly.

Question: One of the emission lines of the hydrogen atom has a wavelength of 94.9 nm.

a). In what region of the electromagnetic spectrum is this emission found?
      microwave, gamma ray, infrared, radio frequency, ultraviolet, x-ray, visible

b). Determine the initial and final values of n associated with this emission.

Thank you all in advance.

[Borek]

Please read forum rules.

[kentucky_girl]

Please read forum rules.

I'm not sure which infraction you're referring to. Pehaps that I didn't show any attempt to work the problem? I apologize for any infraction that I may have committed. If it came across that I needed my question answered immediately, I didn't mean for it to sound that way.

As for the problem, I think the answer for a may be ultraviolet, http://lot.astro.utoronto.ca/images/spectrum.png judging by that spectrum. I really have no idea how to figure out the initial and final n values. I know that change in n = final - initial, but I'm not sure how to determine these values.

[agrobert]

It seems like you are guessing with that assumption.  Look for an equation in your textbook that involves emission spectra of hydrogen or hydrogen like ions.  You should find an equation that involves n₁ and n₂ or n_i and n_f which are the order levels of emission.

[kentucky_girl]

It seems like you are guessing with that assumption.  Look for an equation in your textbook that involves emission spectra of hydrogen or hydrogen like ions.  You should find an equation that involves n₁ and n₂ or n_i and n_f which are the order levels of emission.

Ok, so I found the equation Ep = Rh(nf^2-ni^2)/(ni^2*nf*2), but since it only gives one value, I don't know where I get the other one unless the initial is zero. And also, I chose ultraviolet because I thought that nanometers = 10^-9, so according to that spectrum graph, that would be ultraviolet.

[enahs]

Your equation looks a little...umm, what?

http://en.wikipedia.org/wiki/Rydberg_formula#Rydberg_formula_for_hydrogen


There are various ways to determine n, but it is easiest to set the first equal to 1 and solve for the other, if you get a reasonable whole number check. If not, set it to 2 and repeat. Go through various series (see link). After a little experience, or reading about the series, it should be obvious based on the wavelength which series it should be so you do not have to guess and just solve for the 'excited level'.

[Borek]

Your equation looks a little...umm, what?

It is correct,  just transformed to common denominator form.