atoms with a valence electron behave like little microscopic magnets. atoms can have magnetic moments because of: select all options that apply. (for atoms with odd mass numbers, the nucleus can also have quantum spin, which would contribute to the magnetic moment of an atom but the nucleus' magnetic moment is 2000 times weaker than the electrons' because protons are 2000 times heavier than electrons. so materials' magnetic properties are mostly just from the electrons. however, chemists sometimes use a technique called nmr (nuclear magnetic resonance) in which they are sensitive to the nuclear spin.)