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Nuclear Chemistry


alpha particle

particle identical to a helium ion (He2+) that is emitted during the decay of radioactive elements


matter consisting of antiparticles such as antiprotons, antineutrons, and positrons

beta particle

high-energy electron released when a neutron decays into a proton in the nucleus

chain reaction

nuclear reaction in which the products of the reaction can trigger more nuclear reactions

containment system

structure that shields against radiation and contains the main reactor and the moderator of a nuclear reactor

control rod

rod that can be inserted into a nuclear reactor to capture neutrons and slow down the rate of a chain reaction

critical mass

minimum mass of fissile substance that can sustain a chain reaction


able to undergo a nuclear chain reaction

gamma ray

high-energy electromagnetic radiation

magic number

specific number of protons or neutrons that makes a nucleus more likely to be stable

mass defect

difference between the total mass of the individual nucleons that make up a nucleus and the actual mass of the nucleus

mass-energy equivalence equation

equation that relates energy and mass, formulated by Einstein; given as E=mc2E=mc^2

neutron moderator

substance in a nuclear reactor that slows down fast neutrons, enabling them to initiate nuclear reactions

nuclear binding energy

energy required to break a nucleus into its component nucleons

nuclear chemistry

field of chemistry that studies changes in atomic nuclei

nuclear fission

process in which a nuclide splits into two or more smaller nuclides

nuclear fusion

process in which two or more nuclides combine to form a larger nuclide

nuclear reaction

reaction in which one or more nuclides change to form one or more new nuclides


proton or neutron in an atomic nucleus


atomic nucleus with a specific number of protons and neutrons

particle accelerator

large construction that uses electromagnetic fields to accelerate particles to relativistic speeds


antiparticle of an electron, which has the same mass as an electron and a positive charge equal in magnitude to the negative charge of an electron


process by which unstable nuclei break down into other, smaller nuclei over time, releasing particles and/or energy


Isotope with an unstable nucleus that experiences radioactive decay

strong nuclear force

short-range force that acts between protons and neutrons, keeping the nucleus together

subcritical mass

amount of fissile material insufficient to sustain a chain reaction

supercritical mass

amount of fissile material sufficient to start a chain reaction resulting from spontaneous fission


conversion of one nuclide into another

transuranium element

element that has a higher atomic number than that of uranium, which has an atomic number of 92

zone of stability

region that represents stable, nonradioactive isotopes on a graph of the neutron number versus the proton number for all known isotopes