For example the orbital angular momentum, for the hydrogen atom. Is this the total angular momentum of the atom(electron and proton) or just the electron?
I am asking because, I am learning about how the wave function of the hydrogen atom was exited to include spin. It was necessitated because of (or something similar) the Stern-Gerlach experiment http://www.nyu.edu/classes/tuckerman/adv.chem/lectures/lecture_9/node1.html In the link above, it claims that the beam splits into two because of the magnetic moment or spin of the electrons. I understand that electron spins cancel out in atoms leaving a net spin of up or down. But I was just wondering what about the spin of the nucleus? The net spin of all the electrons would just be the spin of one electron (essentially?) How can one electron influence a whole atom. Especially Silver atoms where there a lot of electrons and a relatively large nucleus.
That's a bit badly worded. What I mean is, from the experiment the only thing you can really conclude is that the entire atom has a certain magnetic moment which causes it react to the field. What justification is given to consider the electrons magnetic moment affects the beam.