Science, Tech, Math › Science Electron Spin Definition in Chemistry Chemistry Glossary Definition of Electron Spin Share Flipboard Email Print MEHAU KULYK/SCIENCE PHOTO LIBRARY / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 08, 2019 In atomic physics and chemistry, electron spin is a property of an electron that is loosely related to its spin about an axis and its angular momentum. Two electron spin states are allowed, which are described by the quantum number ms, with values of +½ or -½ . The spin of an electron isn't as easily visualized as the spin of an ordinary object, such as a marble. Spin has a definite magnitude and it does have a direction, but quantization makes this more complicated than direction using regular vectors. The SI unit of spin is the Newton meter second (N·m·s). This is the same unit as angular momentum in classical mechanics. However, spin is often calculated as the spin angular momentum divided by the reduced Planck constant ħ, yielding a dimensionless value. Uses There are practical applications of electron spin. These include nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), electron spin resonance spectroscopy, and giant magnetoresistive (GMR) drive head technology.