Radioactivity is the act of emitting radiation spontaneously. French scientist, Henri Becquerel discovered radioactivity in 1896. Henri Becquerel, found that a lump of uranium rock was giving off rays.
His studies were continued by Marie and Pierre Curie who found that the rock contained the new elements, radium and polonium. These were giving off most of the rays.
Now we know who discovered radioactivity, let’s discuss it more. Substances which give off radiation naturally are said to be radioactive. Each element has a number of isotopes. Those that give off radioactive radiation are called radioisotopes.
There are three sorts of radiation, alpha rays, beta rays and gamma rays. As the radioisotopes give off radiation, their atoms break up, and change into atoms of another substance. This is known as radioactive decay.
The time taken for radioactive decay is measured in half lives. The half life of a radioisotope is the time taken for half of its atoms to break up. Some radioisotopes have half lives of thousands of years, and others have half lives of less than a second.
Radiation from radioactive substances can be harmful. However, radioactive substances also have many valuable uses, in medicine, industry and science.
Content for this question contributed by Daniel Thorne, resident of Petaluma, Sonoma County, California, USA