textbook 1A 15

[405669838]

"In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line."

I know that n1=1 because it is in the lyman series since it is UV light, and I know to find the frequency by converting nm to meters and using c=λv. I know that I am supposed to use Rydberg's equation to figure out what n2 is, but I seem to be struggling with the basic math of it.

[grace salvestrin 1J]

hi!

so I think that n=1 would actually be the final value (n2) instead of the initial n value (n1). Can someone back me up on this though?
After that, I think you could use the En= -hR/n^2 equation or you could also use the equation where v = R((1/(n1)^2) - (1/(n2)^2)). I think this second equation is a little more straightforward and might help you with the math.

I hope this helps some!

[Rachel Fox - 3F]

N=1 is the final value. To solve the problem, first find the velocity with the wavelength given, and then plug this value and the final energy level of 1 into the equation v=R(1/n2^2-1/n1^2) and solve for n1 (initial energy level). I also believe you could use the equation deltaE = Ef-Ei. DeltaE would be the energy with the wavelength given and Ef would be the energy when n=1 and Ei (and the energy level for Ei) is what you are trying to find.

[Adele Nguyen 2G]

I was having trouble with this problem earlier as well. Another method you could use is to:
1) Find the energy using the wavelength given (102.6 nm = 1.026 x 10^-7 m).
- plug the wavelength into E = -h(c/lambda)
2) Plug in the energy to
For R, I used 2.178 x 10^-18J (The R given in the equations sheet is in Hz, so I multiplied by Planck's constant to get the unit in J).
3) Since we know that nf is 1, use the equation to solve for ni.

[Rose Arcallana 2B]

hi!

so I think that n=1 would actually be the final value (n2) instead of the initial n value (n1). Can someone back me up on this though?
After that, I think you could use the En= -hR/n^2 equation or you could also use the equation where v = R((1/(n1)^2) - (1/(n2)^2)). I think this second equation is a little more straightforward and might help you with the math.

I hope this helps some!

Hi so quick question, what kind of numbers were you getting because I used the second equation with v = R((1/(n1)^2) - (1/(n2)^2), but I'm still not getting the right answer. Would you mind explaining a little? Thanks! :)

[grace salvestrin 1J]

hi!

so I think that n=1 would actually be the final value (n2) instead of the initial n value (n1). Can someone back me up on this though?
After that, I think you could use the En= -hR/n^2 equation or you could also use the equation where v = R((1/(n1)^2) - (1/(n2)^2)). I think this second equation is a little more straightforward and might help you with the math.

I hope this helps some!

Hi so quick question, what kind of numbers were you getting because I used the second equation with v = R((1/(n1)^2) - (1/(n2)^2), but I'm still not getting the right answer. Would you mind explaining a little? Thanks! :)

Hi!

So I think I was actually wrong about n=1 being the final value, it's kind of conusing me but I think that n=1 is actually the n2 value not n1. If you plug in 1 for the n=1 value you should get the right answer now. First you should divide c/wavelength=v and then plug v into the equation with Rydberg's constant and simplify from there to find n2.

So sorry I messed that up!!