Chemistry
posted by Lauren
What is the wavelength of the transition from n=4 to n=3 for Li2+? In what region of the spectrum does this emission occur? Li2+ is a hydrogenlike ion. Such an ion has a nucleus of charge +Ze and a single electron outside this nucleus. The energy levels of the ion are Z^2RH/n^, where Z is the atomic number
okay I saw the rydberg formula but how am i or what numbers am i supposed to plug where

drwls
The energy levels are
En = Z^2RH/n^2
You left out the 2.
In your case, calculate En for Z = 3, with n = 4 and again for Z = 3 and n=3. Call those energy numbers E4 and E3.
E4  E3 is the wave number (1/wavelength) of the photon emitted.
Invert that to get the wavelength 
DrBob222
DrWLS showed you what to do.
1/lambda = R_{H}Z^{2}*[(1/N_{1}^{2})(1/N_{2}^{2}].
R_{H} = 1.0967758341 x 10^7
Z = 3
N_{1} = 3
N_{2} = 4
Solve for lambda. 
Lauren
okay so it should look like this
1/lambda= 1.0967758341 x 10^7(3^2)*[(1/3^2)(1/4^2)]
1.0967758341 x 10^7(9)(.0486)
i got 4798394.274 
DrBob222
I don't get that. Your work LOOKS ok to me except your answer is 1/lambda. You need to take the reciprocal, right?

Lauren
so i got 1/4797297.498

DrBob222
Plug that into your calculator; i.e., divide 1 by that large number and the answer will be the wavelength. That's what you are trying to find.

DrBob222
One note.
Since you are carrying all the other numbers to such high precision, I would suggest you carry the 0.0486 you obtained to the same number of significant figures. 
Lauren
so I did 1 divided by 4797297.498
and got 2.085 X 10^7 
DrBob222
That's what I have. Usually the answer is expressed either in Angstrom units or in nanometers. Your answer is 208.5 nm or 2085 Angstroms. Again, if you want to carry that many places for R_{H}, then you are justified in more placed in the answer. I don't know how your professor wants it done. Many use 1.097 x 10^7 for R_{H}.
Respond to this Question
Similar Questions

Chemistry
What is the wavelength of the transition from n=4 to n=3 for Li2+? 
Chem
What is the wavelength of the transition from n=4 to n=3 for Li2+? 
chemistry
What is the wavelength of the transition from n = 2 to n = 1 for Li2+? 
Chemistry
Considering the emission of the hydrogen atom, a. what is the wavelength of the light emitted by the transition from n = 2 to n = 1. b. In what region of the electromagnetic spectrum does this radiation belong? 
Chemistry
Atoms of ionized lithium gas (Li2+) are struck by neutrons moving at a velocity of 1.46e5 m/s. Calculate the shortest wavelength in the emission spectrum of Li2+ under these circumstances. You can assume that all electrons start in … 
chemistry
Atoms of ionized lithium gas (Li2+) are struck by neutrons moving at a velocity of 1.46e5 m/s. Calculate the shortest wavelength in the emission spectrum of Li2+ under these circumstances. You can assume that all electrons start in … 
chemistry
A sample contains Hydrogen atom ,He+ ion, Li2+, & Be3+ ion. In H atom electron is present in 8th orbit, in He2+ e is present in 6th orbit, Li2+ in 5th orbit& in Be3+ electron is present in 4th orbit. All the atoms are deexcited to … 
Chemistry
Consider the Li2+ ion. (a) Calculate the wavelength of light emitted when the electron jumps from the n=4 level to the n=2 level. (b) What is the ionization energy of Li2+ ? 
Chemistry
The Li2+ ion is hydrogenic and has a Lyman series at 740747 cm1, 877924 cm1, 925933 cm1,and beyond. Show that the energy levels are of the form –hcR/n^2 and find the value of R for this ion. Go on and predict the wavenumbers of … 
Physical Chemistry
The Li2+ ion is hydrogenic and has a Lyman series at 740747 cm1, 877924 cm1, 925933 cm1,and beyond. Show that the energy levels are of the form –hcR/n^2 and find the value of R for this ion. Go on and predict the wavenumbers of …