# Problem With Motion of Electron

1. Jan 3, 2016

### Error404!

Are axis of rotation and revolution of an electron revolving a nucleus parallel? if axis of rotation and revolution of earth can be not parallel to each other then why not for electron? We add or subtract (s) = 1/2 (value of spin quantum number) to orbital quantum number (l) to get total angular momentum quantum number(j) according to whether 's' is parallel or antiparallel to 'l'. If they are not parallel then this total angular momentum quantum number can not give correct value of angular momentum of electron. is this all wrong?

2. Jan 3, 2016

### blue_leaf77

Electrons are not to be viewed as revolving nucleus nor rotating around its own axis. An electron can be found anywhere around the nucleus.
That's just the vectorial picture for the formula of the addition of angular momenta if one of them is equal to 1/2. For a pair of angular momenta $J_1$ and $J_2$, the general formula the sum of them is $|J_1-J_2|,|J_1-J_2|+1, \ldots , J_1+J_2-1,J_1+J_2$. When none of the two angular momenta is equal to $1/2$, you have more than two possible values for the sum. In that case, the naming of "parallel" and "anti-parallel" won't be relevant anymore.