What is the definition of radioactivity?

Radioactivity is a term that refers to the emissions from atomic nuclei due to changes in those nuclei. Those changes will occur as a result of instability of isotopes of certain elements. These atoms have a nuclear structure that is inherently unstable for whatever reason. And any unstable nucleus will eventually decay in a manner characteristic of that particular atom (radioisotope). We term the activity associated with the natural changes due to nuclear instability radioactive decay. As you can guess, different things might appear as an expression of the radioactivity of a radioisotope, and they'll vary according to the radioisotope being inspected.

We could say that the elements on the upper end of the periodic table are radioactive, and these elements, the ones beginning with bismuth, have no nuclear configurations that permit them to avoid instability and their eventual radioactive decay. Additionally, we know that there are isotopes of other elements (lighter ones) that are not stable, and these radioisotopes are radioactive and will decay in time. Lastly, there are the elements technetium and promethium, which are the only elements with atomic numbers below that of bismuth that have no stable isotopes.

The emissions we might gather under the umbrella of radioactivity include both particulate radiation and radiation in the form of energy, or electromagnetic radiation. Your investigation of the instabilities associated with atomic structure and what it is that results is just beginning. Use the links below to check facts and learn more.