Generation Leptons Quarks
I Electron (1) Up (-5) Electron neutrino (-10-6) Down (-10)
II Muon (207) Charm (-3,000) Muon neutrino (-10-6) Strange (-200)
Ordinary matter is made up by the Generation I particles: the electron, the electron neutrino, and the up and down quarks. The mass is in parentheses, in electron units. The masses of quarks are uncertain; the neutrino masses practically unknown. Note that up and down quarks are much lighter than proton and neutron which they make. Much of the mass of a nuclear particle is associated with the binding of the quarks together.
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