Question

What gives rise to the angular momentum of an atom? Give reason why the spin angular momentum becomes zero in certain cases.

Answer 1

Angular momentum is generated by the motion of a particle in space. Spin is not associated with the movement in space. Spin is an internal, purely quantum characteristics that cannot be explained within the framework of relativistic mechanics. Interaction compensation is the reason that spin equals zero. For example, when the spins of the two electrons are antiparallel.