Radioactivity Key Terms

nuclear decay

The process by which an unstable atomic nucleus loses energy by emitting radiation, resulting in the transformation of the nucleus into a different element or isotope.

chemical change

A process that involves the rearrangement of the molecular or ionic structure of a substance, resulting in the formation of new chemical substances.

nuclear radius

The distance from the center of the nucleus to the boundary within which the nucleons are found, typically related to the number of nucleons.

nucleon number

The total number of protons and neutrons in the nucleus of an atom, which determines the atomic mass and influences the nuclear radius.

nuclear density

The mass per unit volume of a nucleus, calculated using the formula: density = mass/volume.

mass defect

The difference between the mass of an assembled nucleus and the sum of the individual masses of its constituent protons and neutrons.

nuclear density

The density of a nucleus, which is approximately constant across different elements, indicating that nuclear matter is packed closely together.

neutron-proton ratio

The ratio of neutrons to protons in a nucleus, which influences nuclear stability and decay processes.

nuclear radius

The distance from the center of a nucleus to the boundary within which the nucleons are contained.

nucleon number

The total number of protons and neutrons in an atomic nucleus, which determines the mass of the nucleus.

mass defect

The difference between the total mass of the individual nucleons and the mass of the nucleus, indicating the energy released when nucleons bind together.

binding energy

The energy required to separate a nucleus into its individual nucleons, equivalent to the mass defect multiplied by c², where c is the speed of light.

binding energy

The energy required to disassemble a nucleus into its constituent protons and neutrons, calculated using the formula E = mc².

mass defect

The difference between the mass of an assembled nucleus and the sum of the masses of its individual nucleons, which accounts for the binding energy.

binding energy per nucleon

The energy required to remove a nucleon from the nucleus, expressed per nucleon.

nuclear stability

The condition of a nucleus being stable against radioactive decay, often related to the neutron-proton ratio.

Energy Release in Fission

The process where a heavy nucleus splits into smaller nuclei, releasing a significant amount of energy due to the mass defect.

Energy Release in Fusion

The process where light nuclei combine to form a heavier nucleus, releasing energy as a result of the binding energy per nucleon being greater in the product nucleus.

Induced fission

The process by which a heavy nucleus splits into two or more lighter nuclei, accompanied by the release of energy and additional neutrons, often initiated by the absorption of a neutron.

Chain reaction

A series of reactions where the products of one reaction initiate further reactions, commonly seen in nuclear fission where released neutrons cause additional fission events.

Chain Reaction

A process where the products of a reaction cause further reactions, leading to a self-sustaining series of events.

Control Rods

Materials used in nuclear reactors to absorb neutrons and regulate the rate of the chain reaction.

neutron

A subatomic particle found in the nucleus of an atom, with no electric charge and a mass approximately equal to that of a proton.

moderator

A material used in nuclear reactors to slow down fast neutrons, increasing the likelihood of fission events.

Controlled fission

A nuclear fission process where the reaction rate is regulated to produce a steady output of energy, typically used in nuclear reactors.

Uncontrolled fission

A nuclear fission process where the reaction rate is not regulated, leading to a rapid release of energy, as seen in nuclear explosions.

contamination

The presence of radioactive material on surfaces or within objects, which can lead to exposure to radiation.

irradiation

The process of exposing an object or person to radiation, which may come from a radioactive source.

Safety measures

Protocols and practices designed to minimize risks when handling radioactive sources.

Radioactive sources

Materials that emit radiation, which can be hazardous and require careful handling.