Module 8
1. Module 8
1.26. Module Glossary
Module 8—Nuclear Decay, Energy, and the Standard Model of the Atom
Module Glossary
activity or decay rate: the number of nuclei in a sample that decays in a given time interval
antimatter: a form of matter that has properties opposite to its normal-matter counterpart; an extension of the concept of normal matter that is made up of particles where antimatter is made up of antiparticles
All particles have an antiparticle.
antineutrino: a tiny subatomic particle with no charge emitted with 
in beta decay
alpha particle: two protons and two neutrons bound together to form a stable particle identical to a helium nucleus
atomic mass: the weighted mean atomic mass number of the element’s natural isotopes
This number is given on the periodic table.
atomic mass number (A): the number of nucleons in an atom’s nucleus
atomic number (Z): the number of protons in the nucleus
The atomic number uniquely identifies the element.
becquerel (Bq): the unit of radioactivity equal to one decay per second
beta particle: an electron emitted by the nucleus when a neutron splits into a proton and electron during the beta decay process
binding energy: the net energy required to liberate all of the protons and neutrons in a nucleus (overcome the strong nuclear force)
bubble chamber: a device that tracks particles using bubbles in liquefied gas
CERN: Conseil Européen pour la Recherche Nucléaire (world’s largest particle physics laboratory)
CERN had the first web server and posted the first page on the World Wide Web. See CERN’s website to see that historic first page.
cloud chamber: a device that tracks particles using condensed gas vapours
daughter element: the element produced by a decay process
fission: when a nucleus with more than 120 nucleons splits into smaller nuclei with greater binding energy per nucleon
fundamental particle: a particle that cannot be divided into smaller particles; an elementary particle
fusion: when a nucleus with fewer than 60 nucleons combines with another to form a larger nucleus with greater binding energy per nucleon
gluon: a mediating particle for the strong nuclear force
graviton: a hypothetical mediating particle for the gravitational force
half-life: the time it takes for half the radioactive nuclei in a sample to decay
isotope: an atom that has the same number of protons but a different number of neutrons and, therefore, a different atomic mass number
mediating particle: a virtual particle that carries a fundamental force
nucleon: a proton or neutron
neutrino: a tiny subatomic particle with no charge emitted with a positron in beta-positive decay
neutron: a neutral particle found in the nucleus
parent element: the original element in a decay process
plasma: ionized gas in which the electrons have been separated from the nucleus
positron: the antimatter to an electron
It is the same type of particle but has an opposite charge. Unlike electrons, positrons are scarce.
proton: a positively charged particle found in all nuclei
quark: a fundamental particle in the hadron family
standard model: the current theory describing the nature of matter and the fundamental forces
transmutation: decay or change into a different element
virtual particle: a particle that exists for such a short time that it cannot be detected
