The discovery of the phenomenon of radioactivity occurred at random in 1896 by the physicist Henri Becquerel. He experimented with uranium salts and when he tried to investigate residuals about phosphorescence. At the same time, Pierre and Marie Curie, who also worked on the phenomenon, used this discovery and explored various elements, revealing the elements of polonium and radium and giving the phenomenon the name radioactivity. Today, radioactive materials are used for the benefit of humans in medicine for locating and preventing cancer, in archeology, and in determining the age of bones or old buildings and industry