Modern Chemistry – Chapter 21: Nuclear Chemistry
Nucleon
A proton or neutron.
Nuclide
An atom that is identified by the number of protons and neutrons in its nucleus.
Mass Defect
The difference between the mass of an atom and the sum of the masses of the atom’s protons, neutrons, and electrons.
Nuclear Binding Energy
The energy released when a nucleus is formed from nucleons.
Nuclear Shell Model
A model which represents nucleons as existing in different energy levels, or shells, in the nucleus.
Nuclear Reaction
A reaction that affects the nucleus of an atom.
Radioactive Decay
The disintegration of an unstable atomic nucleus into one or more different nuclides, accompanied by the emission of radiation, the nuclear capture or ejection of electrons, or fission.
Nuclear Radiation
The particles that are released from the nucleus during radioactive decay, such as neutrons, electrons and protons.
Radioactive Nuclide
A nuclide that contains isotopes that decay and that emit radiation.
Alpha Particle
A positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons.
Beta Particle
A charged electron emitted during certain types of radioactive decay, such a beta decay.
Positron
A particle that has the same mass and spin as an electron but that has a positive charge.
Electron Capture
The process in which an inner orbital electron is captured by the nucleus of the atom that contains the electron.
Gamma Ray
The high-energy photon emitted by a nucleus during fission and radioactive decay.
Half-Life
The time required for half of a sample of radioactive substance to disintegrate by radioactive decay or by natural processes.
Decay Series
A series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached.
Parent Nuclide
A radionuclide that yields a specific daughter nuclide as a later member of a radioactive series.
Daughter Nuclide
A nuclide produced by the radioactive decay of another nuclide.
Radioactive Dating
The process by which the approximate age of an object is determined based on the amount of certain radioactive nuclides present.
Radioactive Tracer
A radioactive material that is added to a substance so that its distribution can be detected later.
Nuclear Waste
Waste that contains radioisotopes.
Nuclear Fission
The splitting of the nucleus of a large atom into two or more fragments; releases additional neutrons and energy.
Chain Reaction
A continuous series of nuclear fission reactions.
Critical Mass
The minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction.
Nuclear Reactor
A device that uses controlled nuclear reactions to produce energy or nuclides.
Nuclear Power Plant
A facility that uses heat from nuclear reactors to produce electrical energy.
Shielding
A radiation-absorbing material that is used to decrease radiation leakage from nuclear reactors.
Control Rod
A neutron-absorbing rod that helps control a nuclear reaction by limiting the number of free neutrons.
Moderator
A material that slows the velocity of neutrons so that they may be absorbed by the nuclei.
Nuclear Fusion
The combination of the nuclei of small atoms to form a larger nucleus; releases energy.