Definition

Noun 1. The property of certain unstable atomic nuclei of spontaneously emitting energy and subatomic particles: This is the spontaneous disintegration of atomic nuclei, accompanied by the emission of radiation in the form of alpha particles, beta particles, or gamma rays. 2. The radiation so emitted: The streams of particles or rays themselves that are given off during radioactive decay.

Usage

• Radioactivity is a fundamental property of some elements, such as uranium and radium.
• Scientists measure radioactivity in units like becquerels or curies.
• The radioactivity of the material decreased over time as it decayed.
• Handling materials with high levels of radioactivity requires special protective equipment.

Advanced Usage

• Natural radioactivity: The radioactivity exhibited by naturally occurring isotopes like carbon-14 or potassium-40.
  • The natural radioactivity in granite is very low but measurable.
• Induced radioactivity: Radioactivity created in a material that is normally stable, typically through bombardment with particles.
  • The sample showed induced radioactivity after being exposed to the neutron beam.

Variants and Related Words

• Radioactive (adj): Possessing or exhibiting radioactivity.
  • The waste from the nuclear plant is highly radioactive.
• Radiocativity is a less common, alternate spelling.

Synonyms

• Radiation (in the context of the emitted rays/particles)
• Radioactive decay
• Nuclear disintegration

Related Phrases and Terms

• Background radioactivity: The low-level ionizing radiation constantly present in the environment from natural and artificial sources.
  • The Geiger counter detected a slight increase above the normal background radioactivity.
• Radioactivity decay series/chain: A series of radioactive decays from a parent isotope until a stable isotope is formed.
  • Uranium-238 begins a long radioactivity decay series that ends with lead-206.

Noun

1. the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay