Berkelium has no commercial, industrial, or medical applications. It is a synthetic radioactive element produced in extremely tiny quantities, and its uses are confined entirely to scientific research. The two primary roles it plays are serving as a target material for creating new superheavy elements and helping scientists understand how the heaviest atoms on the periodic table form chemical bonds.
Creating New Elements
Berkelium’s most high-profile use is as a building block for discovering elements that don’t exist in nature. It was essential to the creation of tennessine, element 117 on the periodic table. No other element could serve as the starting material for that discovery.
The process works by exploiting berkelium’s 97 protons. In 2009, Oak Ridge National Laboratory in Tennessee produced 22 milligrams of berkelium-249 and shipped it to the Joint Institute for Nuclear Research in Dubna, Russia. There, the berkelium was applied as a thin film onto a strip of titanium, creating a target. Scientists then fired an intense beam of calcium ions (each carrying 20 protons) at the berkelium target at a rate of 7 trillion ions per second, for 150 consecutive days. On the rare occasions when a calcium nucleus fused with a berkelium nucleus, the combined 117 protons formed a new, superheavy atom of tennessine.
Only a handful of tennessine atoms were produced across the entire experiment. Those few atoms were captured in silicon detectors, where their distinctive radioactive decay signatures confirmed the discovery. Follow-up confirmation experiments were conducted in 2012 using additional berkelium from Oak Ridge, and further work took place at the GSI Helmholtz Centre for Heavy Ion Research in Germany. Without berkelium, none of this would have been possible.
Understanding How Heavy Atoms Bond
Berkelium also plays a growing role in fundamental chemistry. Scientists have long understood how lighter elements share and exchange electrons to form bonds, but the behavior of the heaviest elements is far less clear. Berkelium sits deep in the actinide series, where electrons occupy a set of orbitals (called 5f orbitals) that behave in unusual and hard-to-predict ways. Studying berkelium’s chemistry helps researchers test whether bonding models developed for lighter actinides like uranium still hold true for the heaviest ones.
A landmark example came when researchers synthesized “berkelocene,” an organometallic compound in which a berkelium atom sits sandwiched between two ring-shaped carbon structures. The entire experiment used just 0.3 milligrams of berkelium-249. Using X-ray diffraction on a single crystal, they confirmed that the berkelium ion forms direct bonds with carbon atoms and that its 5f electrons participate in meaningful, covalent overlap with the surrounding carbon rings. The structure closely resembles uranocene, a well-known uranium compound, suggesting that certain bonding principles do carry across the actinide series. Spectroscopic and computational analysis backed up the finding.
This kind of work matters because it fills in a largely blank region of the periodic table. Berkelium’s chemistry also draws interest because its ability to switch between different oxidation states (essentially, different levels of electron loss) is sensitive to the chemical environment around it, similar to cerium, a much lighter and more abundant element. That parallel gives scientists a useful comparison point for understanding periodic trends.
Why So Little Exists
Berkelium does not occur naturally on Earth. It is produced inside nuclear reactors by bombarding other heavy elements with neutrons over long periods. The sole production facility capable of making usable quantities is the High Flux Isotope Reactor at Oak Ridge National Laboratory, where berkelium-249 is created and then purified in a specialized radiochemical processing center.
The quantities are vanishingly small. A typical available batch might be around 0.3 milligrams, with larger production runs yielding less than 16 milligrams. That scarcity alone rules out any practical commercial use. Compounding the problem is berkelium-249’s half-life of just 330 days. From the moment it’s produced, it steadily decays into californium-249, meaning researchers are working against the clock. The 22-milligram shipment used for the tennessine discovery, for instance, had to be fabricated into a target and bombarded before too much of it transformed.
Physical Properties
Berkelium is a silvery, radioactive metal that is solid at room temperature. It has a melting point of around 986°C (1,807°F) and a density of roughly 14 grams per cubic centimeter, making it about twice as dense as iron. In practice, though, almost no one has ever handled a visible piece of it. The amounts produced are so small that most experiments work with microgram or sub-milligram samples, and all handling requires specialized shielding and remote manipulation because of its intense radioactivity.
Because of the radiation hazard and extreme scarcity, berkelium remains one of the least-studied elements on the periodic table. Every experiment involving it is a significant logistical undertaking, requiring coordination between national laboratories and careful planning around its short useful lifespan. Its value lies entirely in what it teaches scientists about the fundamental behavior of matter at the heaviest end of the periodic table.