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.
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  • Atom
  • Baryon
  • 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.
  • Meson - Text by M. Alan Kazlev
    Particles composed of a quark and an antiquark; the lowest mass mesons (the pi and K mesons) have masses intermediate between leptons and baryons. All mesons are unstable.
  • Neutrino - Text by M. Alan Kazlev; additions by Adam Getchell
    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.
  • 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.
  • Nuclear Engineering
  • Nuclear Fission - Text by M. Alan Kazlev
    The process whereby the nucleus of an unstable (radioactive) heavy element spontaneously splits into two smaller nuclei, releasing energy and charged particles.
  • Nuclear Physics - Text by M. Alan Kazlev
    The study of the physical processes at the scale of the atomic nucleus. Concerns itself with the structure and behavior of the atomic nucleus according quantum mechanics and particle physics; with practical applications in the working of nuclear reactors, radioactive fission, and fusion burning in the interior of stars.
  • Nuclear Reaction - Text by M. Alan Kazlev
    A self-perpetuating chain reaction involving the production of heavy nuclei from the fusion of lighter ones, or lighter nuclei from the fission of heavier ones.
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    A power plant that uses controlled atomic fission or fusion to generate energy.
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    The production of new elements that occurs naturally in stars via nuclear reactions, and in supernova explosions. Nucleosynthesis is also an important part of alchemics.
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    The era following the Leptonic Era, between 1 second and 1,000 seconds after the Big Bang, in which light elements (helium and deuterium) are synthesized during the hot early phases of the hot Big Bang.
  • Nucleus, Atomic - Text by M. Alan Kazlev
    The central part of an atom, made up of protons and neutrons, and containing nearly all of the atomic mass.
  • Photon - Text by M. Alan Kazlev
    The quantum unit of electromagnetic radiation, having some properties of a wave. For each wavelength, the photon has a different energy.
  • Proton-Proton Chain - Text by M. Alan Kazlev
    A series of three thermonuclear reactions that convert hydrogen nuclei to helium nuclei, converting a tiny amount of mass into energy. The process is efficient at temperatures above 10,000,000 K. In most less massive stars, this chain is the primary source of heat and radiation. The proton-proton chain converts hydrogen into helium releasing energy in the form of particles and gamma-rays. Hydrogen is converted into helium in a chain of reactions. The first reaction takes an average of 1 billion years to occur while the others are much shorter. Generally there are so many hydrogen nuclei that the 1 billion year waiting period does not stop it from producing tremendous radiation.
  • 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.
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Development Notes
Text by M. Alan Kazlev
Initially published on 19 December 2001.