Key Concepts: Radioactivity & Stability

Core Definitions

• Radioactivity: The spontaneous emission of radiation from an unstable nucleus.
• Nuclear Stability: Depends on the ratio of neutrons to protons; too many or too few neutrons = unstable.
• Band of Stability: The zone on a graph of neutrons vs. protons where stable nuclei exist.
• Alpha Decay: Emission of an alpha particle (²₄He); reduces atomic number by 2 and mass number by 4.
• Beta Decay: A neutron converts to a proton and emits a beta particle (electron); atomic number increases by 1.
• Gamma Radiation: High-energy electromagnetic radiation emitted from the nucleus; no change in mass or atomic number.