How many radioactive elements are found in nature?

Thirty-nine radioactive elements have been identified by scientists, but there may be others not yet discovered. Some of the elements below are suspected to be radioactive but are very rare and therefore hard to study. Radioactivity was first noticed in 1895 by Wilhelm Roentgen, but he mistook the fluorescence he observed as a form of X-rays. The discovery of radioactivity is attributed to Antoine Becquerel, who identified and described the differences between radioactivity and X-rays....

Thirty-nine radioactive elements have been identified by scientists, but there may be others not yet discovered. Some of the elements below are suspected to be radioactive but are very rare and therefore hard to study. Radioactivity was first noticed in 1895 by Wilhelm Roentgen, but he mistook the fluorescence he observed as a form of X-rays. The discovery of radioactivity is attributed to Antoine Becquerel, who identified and described the differences between radioactivity and X-rays. Pierre and Marie Curie are the scientists most famous for their work on radioactivity. Marie coined the term "radioactivity" and discovered two of the twenty-nine radioactive elements. She and her husband did many experiments to uncover how radioactivity functioned.

Most radioactive elements are Rare Earth Metals, though others are Transition Metals, Alkali Metals, Metalloids, Halogens, and Noble Gases. The identified radioactive elements, alphabetically, are: 

• Actinium (Ac)


• Americium (Am)


• Astatine (At)


• Berkelium (Bk)


• Bohrium (Bh)


• Californium (Cf)


• Copernicium (Cn)


• Curium (Cm)


• Darmstadtium (Ds)


• Dubnium (Db)


• Einsteinium (Es)


• Fermium (Fm)


• Flerovium (Fl)


• Francium (Fr)


• Hassium (Hs)


• Lawrencium (Lr)


• Livermorium (Lv)


• Meitnerium (Mt)


• Mendelevium (Md)


• Neptunium (Np)


• Nobelium (No)


• Plutonium (Pu)


• Polonium (Po)


• Promethium (Pm)


• Protactinium (Pa)


• Radium (Ra)


• Radon (Rn)


• Roentgenium (Rg)


• Ruthorfordium (Rt)


• Seaborgium (Sg)


• Technetium (Tc)


• Thorium (Th)


• Ununhexium (Uuh)


• Ununoctium (Uuo)


• Ununpentium (Uup)


• Ununseptium (Uus)


• Ununtrium (Uut)


• Ununquadium (Uuq)


• Uranium (U)