Meaning of Radioactivity
Radioactivity refers to the spontaneous emission of radiation by an element. It can also be defined as the particles which are emitted from a nucleus as a result of nuclear instability.
During radiation, the small particles of matterScience meaning: Matter is any substance (often a particle) that has mass, and also volume (occupies space). Matter exists in three states, solid, liquid and gas and is made up of... More (α & β particles and electromagnetic radiation γ-rays) are emitted by unstable atomic nuclei.