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?