An element born in a laboratory, existing only thanks to human ingenuity. Berkelium is one of the rarest materials on the planet. Throughout all of history, only a few grams have ever been produced. Every single atom of berkelium was artificially created inside a nuclear reactor.
Berkelium was named after the city of Berkeley, California, where it was first synthesized in 1949. It became the fifth transuranic element discovered by humans. Today, berkelium serves as an irreplaceable tool for creating even heavier elements. It was berkelium that made the discovery of tennessine — element 117 — possible.
Berkelium is a silvery radioactive metal from the actinide group. It is produced in specialized nuclear reactors through prolonged neutron irradiation of curium or plutonium. The process takes months, and the yield is only milligrams. In air, berkelium quickly oxidizes and darkens due to intense radioactivity.
Berkelium's main purpose is to serve as a target for synthesizing superheavy elements. In 2010, berkelium-249 was the key to synthesizing tennessine. This is one of those elements that exists purely for the sake of science.
Berkelium is an extremely radioactive metal. It emits alpha particles and beta rays that destroy living cells. If ingested, it accumulates in bones and liver, causing severe radiation damage. Working with berkelium is only possible in specialized hot cells with remote manipulation and multilayer radiation shielding.
Berkelium was named after Berkeley, California. Interestingly, the city itself was named after philosopher George Berkeley, who never actually visited the place.
Only a few grams of berkelium have ever been produced in all of human history. One gram would cost millions of dollars — if it were even for sale.
In 2010, just 22 milligrams of berkelium-249 became the key to discovering tennessine — element 117. Those milligrams took 250 days to prepare in a reactor.
Metallic berkelium has a beautiful silvery luster. But you can barely see it — it darkens within minutes in air due to radioactive self-heating.
The most stable isotope, Bk-247, survives for 1,380 years. That's long for a transuranic element, but a blink compared to Earth's age of 4.5 billion years.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
247Bk☢ | 247.070307 | synthetic | 1380 years | α |
249Bk☢ | 249.074987 | synthetic | 330 days | β−/α |
Cyclotron bombardment of americium