Berkelium (Bk)


  • Symbol: Bk
  • Atomic Number: 97
  • Atomic Weight: [247]
  • Element Classification: Actinide
  • Discovered By: Lawrence Berkeley National Laboratory team
  • Discovery Date: 1949
  • Name Origin: Named after Berkeley, California, the city where it was discovered, also home to the University of California, Berkeley
  • Density(g/cc): 14.78 (estimated)
  • Melting Point: 986°C
  • Boiling Point: Not accurately known; estimated to be about 2900°C
  • Appearance: Silvery metal, radioactive
  • Atomic Radius(pm): 170 (estimated)


Berkelium was discovered in December 1949 by a research team at the Lawrence Berkeley National Laboratory, led by Albert Ghiorso, Stanley G. Thompson, and Glenn T. Seaborg. The team produced berkelium by bombarding americium-241 with alpha particles (helium nuclei) in the 60-inch cyclotron at Berkeley. This synthesis marked the discovery of the fifth transuranium element. Berkelium was named after the city of Berkeley, California, recognizing the city’s contribution to atomic research and its role as the location of the University of California, Berkeley.

Relation to Other Elements

Berkelium is a member of the actinide series, characterized by its radioactive properties and typical actinide electron configuration. Like other actinides, berkelium exhibits multiple oxidation states, with +3 and +4 being the most common in chemical compounds. Its properties are similar to those of the preceding actinide, curium, and it shares chemical similarities with the lanthanide element terbium.

Natural Occurrence

Berkelium does not occur naturally on Earth due to its instability and radioactive decay. It is produced synthetically in nuclear reactors or particle accelerators through the bombardment of lighter elements with neutrons or charged particles.


Berkelium’s uses are largely confined to scientific research due to its scarcity, radioactivity, and the complexity of its production:

  • Scientific Research: Berkelium has been used in research to synthesize heavier elements, including tennessine (element 117), by serving as a target material in particle accelerators.
  • Neutron Source: The berkelium-249 isotope has potential applications as a neutron source, but its use is limited by its short half-life and the difficulty of producing significant quantities.

The discovery of berkelium contributed to the expansion of the periodic table and the understanding of the synthesis and properties of heavy elements. Despite its limited practical applications, berkelium plays an important role in nuclear and chemical research, particularly in the synthesis of new elements and the study of actinide chemistry.

Curium (Cm)

Californium (Cf)