Muon

In the Standard Model of particle physics, a muon (from Greek letter mu used to represent it) is a semistable fundamental particle with negative electric charge and a spin of 1/2. Together with the electron, the tauon and the neutrinos, it is classified as part of the lepton family of fermions. Like all fundamental particles, the muon has an antimatter partner of opposite charge but equal mass and spin: the antimuon.

Muonic atoms

The muon was the first elementary particle discovered that does not appear in ordinary atoms. Negative muons can, however, form muonic atoms by replacing the electrons in ordinary atoms. Muonic atoms are much smaller than typical atoms because, in order to conserve angular momentum, the more massive muon must be closer to the atomic nucleus than its less massive electron counterpart.

Related Topics:
Elementary particle - Atom - Conserve angular momentum - Atomic nucleus

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A positive muon, when stopped in ordinary matter, can also bind an electron and form the muonium (Mu) atom, in which the muon acts as the nucleus. The reduced mass of muonium, hence its Bohr radius, is very close to that of Hydrogen, hence this short lived atom behaves chemically -- in first approximation -- like its heavier isotopes, Hydrogen, Deuterium and Tritium .

Related Topics:
Reduced mass - Bohr radius - Hydrogen - Deuterium - Tritium

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