Which term denotes the emission of high-energy particles from unstable nuclei?

• A. Radioactivity
• B. Nuclear decay
• C. Half-reactions
• D. Cell Potential

Answer: (A)

Radioactivity describes the spontaneous emission of radiation from unstable atomic nuclei. When a nucleus is unstable, it tends to transform to a more stable state by releasing energy in the form of particles or photons—alpha particles, beta particles, or gamma rays. This emission is the hallmark of radioactivity, the observable phenomenon. Nuclear decay is the process by which the nucleus changes and emits radiation as part of that change, but the term that denotes the emission itself is radioactivity. The other terms—half-reactions and cell potential—relate to redox chemistry and electrochemistry, not nuclear emissions.