An electrically neutral lepton of spin 1/2 and extremely low mass that interacts only via the weak force and gravity and as a consequence can typically pass unimpeded through ordinary matter. A common popular illustration of this is that a burst of neutrinos could pass through a light year's thickness of lead and still retain better than two thirds of its strength. There are three known varieties in conventional matter, one in each generation of particles, associated with electron, muon, and tau leptons.
- Electron - Text by M. Alan Kazlev
An elementary particle with a unit electrical charge and a mass 1/1837 of the proton. Electrons surround the atom's positively charged nucleus and determine the atom's chemical properties.
- Hadron - Text by Anders Sandberg
Matter particle consisting of quarks or antiquarks. Hadrons are divided into mesons, composed of a quark and an antiquark, and baryons, composed of three quarks or three antiquarks.
- Lepton - Text by M. Alan Kazlev
Subatomic particle that is susceptible to the weak nuclear force but not the strong force (the force that binds an atomic nucleus together). There are six leptons: the electron, muon, tau, electron neutrino, muon neutrino, and tau neutrino.
- Neutron - Text by M. Alan Kazlev
Uncharged atomic nuclear particle. It has a mass slightly greater than a proton. In beta decay, a neutron decays into a proton, an electron, and an anti-neutrino.
- Proton - Text by M. Alan Kazlev
One of the two basic elementary particles found the atomic nucleus, the other being the neutron. It has a positive charge equal and opposite that of the electron, and a mass similar to the neutron. Protons have a mass of 1.007276 daltons, or 1.6726 = 10-27 kg.
- Quark - Text by M. Alan Kazlev
The fundamental particles of hadronic matter such as protons, neutrons and mesons. There exist six 'flavors' of quarks: up, down, strange, charm, top and bottom. They are confined to hadrons by the strong force.