Berkelium is a transuranic radioactive chemical element with the symbol Bk and atomic number 97. It is named after Berkeley, California, the location of the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), where it was discovered in December 1949.

Actinide Chemical Elements

The actinide series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

These fifteen actinide elements [Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Californium (Cf), Einsteinium (Es), Fermium (Fm), Mendelevium (Md), Nobelium (No), Lawrencium (Lr)], have very large atomic and ionic radii and exhibit an unusually large range of physical properties.