tl;dr: Brown University chemists used photoelectron spectroscopy on carbon-bismuth molecules to show that triple bonds in heavy elements don't follow the textbook one-sigma-two-pi structure. Due to relativistic effects—electrons moving near light speed cause spin-orbit coupling—the bonds instead appear as one pi bond and two hybrid sigma-pi bonds. The finding, published in Science, could rewrite chemistry textbooks as heavy elements like bismuth gain interest for solar cells and quantum computing.