# Bohr's model question

1. Jun 8, 2007

### shanktank

hi all,
quick question with regards to bohr's model

From what energy level did an electron fall if it emits a photon of 9.38 x 10^-8 wavelength when it reaches fround state within a hydrogen atom?

this is a textbook question so i know the answer is n = 6

attached is a copy of my work, please let me know where i'm going wrong.

File size:
20.9 KB
Views:
126
2. Jun 8, 2007

### Staff: Mentor

You are mixing up n_i and n_f. n_f is the final level, which in this case is the ground state (what does n_f equal?). n_i, the initial level, is what you are trying to find.

3. Jun 8, 2007

### shanktank

oh ok umm is there anywhere that i should know what n_f does equal. does the hydrogen part give a clue or ?

4. Jun 8, 2007

### Staff: Mentor

Ground state is the clue! What's the number of the lowest energy level in the Bohr model?

5. Jun 8, 2007

### Staff: Mentor

I assume that should have said "when it reaches the ground state". Right?

6. Jun 8, 2007

### shanktank

ok heres where i'm not as of now. did i make an error in one or more of the steps?

File size:
27.4 KB
Views:
77
7. Jun 8, 2007

### Staff: Mentor

Yes, you made an error. n_f is an integer, not an energy. What's the orbital number of the lowest energy orbit? (Open the book! )

8. Jun 8, 2007

its not 1?

9. Jun 8, 2007

### shanktank

In atoms with a single electron (essentially the hydrogen atom), the energy of an orbital (and, consequently, of any electrons in the orbital) is determined exclusively by n. The n = 1 orbital has the lowest possible energy in the atom.
from wikipedia

10. Jun 8, 2007

### Staff: Mentor

Of course it is.

I hope you have a textbook to use and not just Wiki.

11. Jun 8, 2007

### shanktank

well replacing that into the equation i have i still get a way off answer?

12. Jun 8, 2007

### shanktank

oh nevermind! awesome thankyou so much for the help Doc