I've read that the properties considered intrinsic to a particle are its mass, spin, and charge. However, unless I am mistaken, both spin and charge can be determined from a particle's magnetic moment. Why are spin and charge considered to be intrinsic instead of magnetic moment then? Sorry if this is a silly question, I'm a physics major but the only physics class I've taken is physics 1. EDIT: I just realized that you'd be trying to determine two quantities with just one equation. In which case, why isn't it that you can't call any two of those properties to be intrinsic and the third to be the one "left over"? Is it arbitrary?