What is the difference between radioactivity and radiation?
It mostly concerns parts of speech and general usage. “Radiation” refers to the actual particles/waves moving a high velocity through space, up to the speed of light. It can be of any form, including non-ionizing radiation like radio waves and visible light. Etymologically speaking “radioactive” means “nuclei *active*ly emitting ionizing *rad*iation”. That is, radioactivity refers to the presence of unstable (active) atomic nuclei which emit ionizing radiation specifically, like gamma rays.
