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Electron spin
Intermediate
Intrinsic angular momentum of ½ħ.
Spin is intrinsic angular momentum of ½ħ with two projections (up or down). It gives electrons a magnetic moment and is essential for the periodic table and magnetism.
Not a literal spinning ball.
Spin-½ needs a 720° rotation to return.
In more detail
Electrons have an intrinsic angular momentum called spin, with magnitude sqrt(3)ħ/2. Spin has two possible projections, up and down, and gives rise to magnetism in atoms.
Real-world uses
- Magnetic resonance imaging uses nuclear spin.
- Spintronics devices use electron spin for data storage.
- Engineers designing MRI machines and spintronic devices rely on the spin of electrons and nuclei.
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Frequently asked questions
Is spin like rotation?
It is an intrinsic quantum property, not literal spinning of a particle.
What values can spin take?
For electrons, spin one half, giving two states.
Is spin a real rotation?
No. Spin is an intrinsic quantum property with no classical equivalent, though it behaves like angular momentum.
Related topics in Quantum Mechanics
Hydrogen atom in quantum mechanics · Quantum numbers · Atomic orbitals · Stern–Gerlach experiment · Pauli exclusion principle · Fermions and bosons