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General Chemistry

Berkelium

Definition and meaning of Berkelium in chemistry.
Berkelium is a synthetic radioactive element with the symbol Bk and atomic number 97. It is part of the actinide series on the periodic table. Scientists named it after the city of Berkeley, California, where they first discovered it.
Berkelium element card: symbol Bk, atomic number 97, atomic mass [247], electron configuration [Rn] 5f⁹ 7s², oxidation states +3, Actinide, f-block, period 7, solid at room temperature.

In more detail

Berkelium is a soft, silvery-white radioactive metal with unique physical properties. It exists in two distinct crystal structures depending on the temperature and pressure. Scientists produce berkelium in tiny milligram quantities within high-flux nuclear reactors.

They do this by bombarding lighter actinide elements with a stream of neutrons. Chemically, berkelium usually shows a +3 oxidation state when dissolved in water. Oxidation state simply refers to the number of electrons an atom gains or loses.

Under strong conditions, scientists can also force berkelium into a stable +4 state. As an f-block element, its chemical traits follow trends seen in heavier actinides. It also shares strong behavioral similarities with its lanthanide counterpart, terbium.

Lanthanides are a related group of metallic elements located higher on the periodic table. Safely handling berkelium requires highly specialized, heavily shielded laboratory facilities. This is due to its intense radiation and the short half-lives of its isotopes. A half-life is the time it takes for half of a radioactive sample to decay.

Key facts

Field
General Chemistry
Symbol
Bk
Atomic number
97
Atomic mass
[247] u
Category
Actinide
Year discovered
1949
Discoverers
Stanley G. Thompson, Albert Ghiorso, and Glenn T. Seaborg
Example
Researchers have primarily utilized berkelium-249 as a target material in particle accelerators. A particle accelerator is a large machine that smashes tiny atomic particles together. Scientists fire lighter atoms at the berkelium target at extremely high speeds. This high-energy collision helps them synthesize even heavier transactinide elements. For instance, scientists successfully used a berkelium target to create the element tennessine. These experiments help physicists understand the fundamental building blocks of our universe.

Frequently asked questions

Does berkelium have any commercial applications?

Currently, berkelium has no practical commercial applications outside of basic scientific research. Its main use remains the laboratory synthesis of heavier, undiscovered elements.

What is the longest-lived isotope of berkelium?

Berkelium-247 is the most stable isotope with a half-life of 1,380 years. However, scientists more commonly produce berkelium-249 for their research experiments.

Related terms

Sources & references

By the Chemistry Dictionary editorial team · Reviewed July 16, 2026