1. Oct 26, 2006

### GLprincess02

The energy (in joules) of an electron energy level in the Bohr atom is given by the expression: $$E_{n}$$= -2.179 x $$10^-18/n^2 J$$where n is the principal quantum number for the energy level. What is the frequency in Hz of the electromagnetic radiation absorbed when an electron is raised up from level with n = 4 to that with n = 9?

I'm unsure of the the formula to use, or even the first step. Any ideas??

2. Oct 26, 2006

### marcusl

First use your formula to calculate the energy difference between the two levels. Second, relate that to frequency. Look in your book for the formula giving energy of a photon (hint: it involves Planck's constant). You can show us what you get if you still have questions.

3. Oct 26, 2006

use the equation $$\Delta E = R_{H}^{*} (\frac{1}{n_{f}^{2}} - \frac{1}{n_{i}^{2}}) = hv$$

4. Oct 26, 2006

### GLprincess02

Ok, so I plugged both of the numbers (4 and 9) into the equation. Then I subtracted answer #1 from answer #2. Then I divided this number by h (6.626E-34). Am I doing this correctly?

5. Oct 26, 2006

### marcusl

Yes, exactly.

6. Oct 27, 2006

### ultranet

this is great!, I could learn something here....

7. Oct 27, 2006

### GLprincess02

Great I got the answer, thanks for all the help!