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  1. Radioactivity | Definition, Types, Applications, & Facts | Britannica

    Dec 6, 2025 · Radioactivity, property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei.

  2. Radioactive decay - Wikipedia

    Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation.

  3. Radioactivity: Definition, Types, Formula, and Applications

    Jun 10, 2025 · Radioactivity occurs when an atom has an excess of energy, mass, or both, making its nucleus unstable. To reach a lower, more stable energy level, it releases energy in the form of …

  4. DOE Explains...Radioactivity - Department of Energy

    Radioactivity is the release of energy from the decay of the nuclei of certain kinds of atoms and isotopes. Atomic nuclei consist of protons and neutrons bound together in tiny bundles at the center of atoms.

  5. Radioactivity and the Types of Radioactive Decay

    May 30, 2021 · Radioactivity is the spontaneous emission of ionizing radiation from nuclear decay and reactions. The three main types of radioactive decay are alpha, beta, and gamma decay, but there …

  6. The Radioactive Atom: An Overview | Radiation and Your Health | CDC

    Feb 22, 2024 · This process is known as radioactivity and the energy that's released is radiation. After an atom expels energy from the nucleus, the composition of the nucleus changes, and we are left …

  7. Radiation Basics | Nuclear Regulatory Commission

    These forces within the atom work toward a strong, stable balance by getting rid of excess atomic energy (radioactivity). In that process, unstable nuclei may emit a quantity of energy, and this …

  8. Radioactivity | Understanding Its Basics & Effects

    May 29, 2024 · Radioactivity is a natural phenomenon involving the decay of unstable atomic nuclei, which release energy in the form of radiation. This process helps us understand atomic structures …

  9. Radioactivity - HyperPhysics

    Radioactive decay rates are normally stated in terms of their half-lives, and the half-life of a given nuclear species is related to its radiation risk. The different types of radioactivity lead to different …

  10. Radiation - Wikipedia

    Graphic showing relationships between radioactivity and detected ionizing radiation Ionizing radiation has many practical uses in medicine, research, and construction, but presents a health hazard if …