Einstein's relativity rules chemical bonds in heavy elements, new research shows

# Summary Brown University chemists have provided the first direct experimental evidence that the traditional textbook model of triple chemical bonds breaks down in heavy elements, where relativistic effects become significant. Using photoelectron spectroscopy, they demonstrated that in carbon-bismuth bonds, Einstein's theory of relativity causes electrons to move so fast that spin-orbit coupling occurs, blurring the distinction between sigma and pi bonds that normally characterize triple bonds in lighter elements.