Posted by Tina on Monday, March 21, 2011 at 12:08am.
The electron in a hydrogen atom is excited and makes a transition from n=2 to n=7
a. calculate the energy of the photon absorbed in joules.
b. calculate the wavelength of the photon in meters
HOW DO I DO THIS?

chemistry  DrBob222, Monday, March 21, 2011 at 12:25am
1/wavelength = R(1/n1^2  1/n2^2)
R = Rydberg constant. I assume you have that in your text or notes.
For n1 you substitute 2 and square it.
For n2 substitute 7 and square it.
From wavelength, you can calculate energy from E = hc/wavelength.
(Note:I arranged n1 and n2 so you would get a positive number for wavelength. You must remember that you are going from 2 to 7 which means energy is absorbed.)