# Angular Momentum of Electron

1. Apr 30, 2010

### Zywo

1. The problem statement, all variables and given/known data

What is the angular momentum of a hydrogen atom in (a) a 4p state and (b) a 5f state? Give your answers as a multiple of h-bar aka (h/2*pi)

2. Relevant equations

Radius of nth orbit = 5.29*10-11 * n^2
Angular Momentum = mvr
V of nth orbit = sqrt ( e^2 / (4*pi*epsilon_0*m*r) )

3. The attempt at a solution

For 4p orbit i plugged in 4 to the equations and got angular momentum is equal to 4 h-bar,
not right however....
Thanks,
David

2. Apr 30, 2010

### Zywo

Solved my own problem, if anyone has this same issue the answer is more simple than i thought. L = h-bar*sqrt(l(l+1)) where l is the orbital quantum number

3. May 3, 2010

### modena679

I tried plugging in 4 for the orbital quantum number and got it to be sqrt(20)*h-bar, but this was incorrect. Did I plug in the wrong number for the orbital?

Thanks,
Spencer

4. May 3, 2010

### nickjer

In the 4p state, n=4 and l=1. Where 'l' comes from the p in 4p. Remember the quantum number 'l' is labeled by s,p,d,f... for l=0,1,2,3,..

You don't use the 'n' when solving for the angular momentum.

5. May 3, 2010

### modena679

Ok, ya I forgot how to find l. Now it works. Thanks for the response