Relativity Shapes Bonds in Heavy Elements

Brown University chemists report experimental evidence that relativistic effects alter triple chemical bonds in heavy-element molecules.

Updated on Nov. 8, 2026 in Chemistry

Photograph of a brass and steel cryogenic apparatus with frosted copper components and a faintly glowing glass chamber on a laboratory bench. — Brown University chemists report experimental evidence that relativity alters triple bonds in carbon-bismuth molecules cooled near absolute zero, published in Science on July 9. AI Illustration. Upload story photo >

Researchers at Brown University found experimental evidence that relativity changes the structure of triple bonds in heavy elements, according to a study published in Science on July 9, 2026. The team examined carbon-bismuth molecules cooled to temperatures near absolute zero.

Why it matters

The findings could influence how chemists describe bonds involving heavy elements, a area where conventional textbook descriptions have long been used. Bismuth is also being investigated as a less toxic alternative to lead in solar cells and in quantum materials research.

Photoelectron spectroscopy, which uses light to eject electrons and measures their energies, showed a carbon-bismuth bond with one pi bond and two hybrid sigma-pi bonds rather than the conventional one sigma and two pi bonds. The extraction does not indicate whether the result has been replicated in other heavy-element systems.

The players

Brown University

A private Ivy League research university in Providence, Rhode Island, whose chemists conducted the study.

The details

Doctoral students Deniz Kahraman and Jie Hui produced the carbon-bismuth molecules with colleagues at Brown University. Heavy atoms carry strong nuclear charge that pushes some electrons to relativistic speeds, which strengthens spin-orbit coupling and alters bonding.

1970s: The idea that relativity matters in heavy elements first emerged.
July 9, 2026: The study was published in Science.

The Big Picture

The result extends theoretical work from the 1970s that first argued relativity matters in heavy elements, and it moves that idea from calculation toward direct experimental evidence. It may prompt chemists to revisit how bonds involving heavy atoms are taught and described.

For students and educators, the findings could eventually change how triple bonds involving heavy elements are presented in chemistry courses. The research also bears on bismuth's growing use as a potential alternative to lead in technologies such as solar cells.

The takeaway

Heavy elements behave differently than lighter ones partly because relativity reshapes their electrons, which means standard bonding models may need refinement for these atoms. Readers following materials science can watch how bismuth research develops as an alternative to toxic lead.