Electron spin is an intrinsic property of electrons, along with their mass and charge. Spin is not a classical rotation. It’s a quantum property and shouldn’t be interpreted literally as spinning. It is quantized, meaning it can only have certain discrete values.
- Quantized Nature: The spin of an electron is always quantized, meaning it can only take on specific values. Electrons have a spin quantum number s=1/2, meaning they can exist in one of two possible spin states:
- “Spin-up” (+1/2+1/2)
- “Spin-down” (−1/2-1/2)
- Magnetic Moment: Due to its spin, the electron generates a tiny magnetic field (magnetic moment), which interacts with external magnetic fields. This property is exploited in techniques like MRI and electron spin resonance (ESR).
- Pauli Exclusion Principle: Electron spin is crucial for the Pauli Exclusion Principle, which states that no two electrons in an atom can have the same set of quantum numbers. This is why two electrons in the same atomic orbital must have opposite spins.
- Intrinsic Property: Unlike orbital angular momentum, which depends on the electron’s motion around the nucleus, spin is intrinsic to the electron itself. It’s as if the electron has an inherent angular momentum that’s always present.