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Berkelium

Dedicated to Bernt Krebs in celebration of his 87th birthday, November 26, 2025

Update – April 2026:ÌýÌý A new Isotope 235-Bk was created

About the Display:

• Bernt Krebs is a distinguished German chemist known for his contributions to inorganic, bioinorganic, and structural chemistry. He has authored over 750 peer-reviewed publications and is among the most highly cited in his field

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• A goniometer head, used to mount single crystals, symbolizes his lasting impact on crystallography
• The model of the ²⁴⁷Bk nucleus – consisting of 97 protons and 150 neutrons—represents the radioactive synthetic actinide berkelium. With a half-life of 1,380 years, it is produced only in microgram to milligram quantities for research
• A fan of playing cards recalls research group work-weekends in Haus Rothenberge and Prof. Krebs’s enthusiasm for DoppelkopfÌý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý Ìý ÌýÌý

More about BK

• Bernt Krebs is widely respected for both his scientific achievements and his generosity in fostering international collaboration. He actively supported graduate exchanges from Münster/Germany to Toledo/USA, broadening his students’ research experience. Over his career, he supervised more than 200 doctoral students, many of whom spent time in Toledo. He also visited ÍÃ×ÓÏÈÉú´«Ã½ÎÄ»¯×÷Æ· and presented his research inÌý 1991

Bk Discovery

• Berkelium was first discovered in 1949 at the University of California, Berkeley. It was produced by S.Thompson, A. Ghiorso, and G. Seaborg by bombarding ²⁴¹Am with helium nuclei for several hours, resulting in the isotope ²⁴³BkÌý

How it got its name: Commemorating city of Berkeley, where it was discovered

Half lives: All isotopes are radioactive. ²⁴⁷Bk ~ 1380 years, ²⁴⁹Bk ~ 320–330 days, ²⁴³Bk ~ 5 hrs

Availability: Extremely limited - only microgram to milligram quantities are typically produced and distributed for research

Physical properties: Metal is silvery; melting point ≈ 986 °C. Many bulk properties remain incompletely characterized because only tiny samples exist

Chemistry and oxidation states: A typical heavy actinide: the +3 oxidation state dominates, with +4 observed in some compounds

About the Contributors: Former members of Prof. Krebs’ research group contributed and willÌý contribute to this dynamic display

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