# Nuclear Chemistry

## Vocabulary

### alpha particle

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

### antimatter

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

### fissile

able to undergo a nuclear chain reaction

### 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 $E=mc^2$

### 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

### nucleon

proton or neutron in an atomic nucleus

### nuclide

atomic nucleus with a specific number of protons and neutrons

### particle accelerator

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

### positron

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

### transmutation

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