Unanswered Questions

Beyond the Proton, Neutron, and Electron

Are there yet more quarks and leptons?

There are two more generations of both quarks and leptons. In the second generation the quarks are called strange and charm. The strange quark was named after particles that contain these quarks. The particles decayed in very different ways and were therefore called strange particles. The charm quark was found in a particle that had a very long, or “charmed” life. The leptons are the muon and muon neutrino. The muon was first called the mu-meson before its true identity was discovered. In the third generation the quarks are called bottom and top. The leptons are called tau and the tau neutrino. The table shows their properties.


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