Electron Spin Definition in Chemistry

Chemistry Glossary Definition of Electron Spin

Stylized red and blue atom


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.


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.

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Helmenstine, Anne Marie, Ph.D. "Electron Spin Definition in Chemistry." ThoughtCo, Aug. 28, 2020, thoughtco.com/definition-of-electron-spin-in-chemistry-604450. Helmenstine, Anne Marie, Ph.D. (2020, August 28). Electron Spin Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-electron-spin-in-chemistry-604450 Helmenstine, Anne Marie, Ph.D. "Electron Spin Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-electron-spin-in-chemistry-604450 (accessed June 2, 2023).