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

    Feb 26, 2026 · 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. What Is Radioactivity? - Energy.gov

    As its name implies, radioactivity is the act of emitting radiation spontaneously. This is done by an atomic nucleus that, for some reason, is unstable; it "wants" to give up some energy in order to shift …

  4. What Is a Radioactive Element? Atoms, Decay & Uses

    6 days ago · A radioactive element is one whose atoms have unstable nuclei that release energy and particles as they break down into more stable forms. This process, called radioactive decay, happens …

  5. 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 …

  6. 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 …

  7. RADIOACTIVE Definition & Meaning - Merriam-Webster

    The meaning of RADIOACTIVE is of, caused by, or exhibiting radioactivity. How to use radioactive in a sentence.