Deuterium

Deuterium emerged because mass spectrometry had revealed that chemical elements were not pure but contained isotopes—atoms with identical chemistry but different masses—and hydrogen, the simplest element, had to have its own heavier sibling waiting to be found.

Harold Clayton Urey (1893-1981) was a physical chemist at Columbia University who recognized that if heavy hydrogen existed, it should be concentrated by fractional distillation. Liquid hydrogen's isotopes would have slightly different boiling points; repeated evaporation and condensation should enrich the heavier fraction.

In 1931, Urey worked with Ferdinand Brickwedde at the National Bureau of Standards, who performed the painstaking distillation of liquid hydrogen near its triple point (about -259 degrees Celsius). George Murphy at Columbia analyzed the resulting samples spectroscopically. They were hunting for a needle in a haystack—theory predicted heavy hydrogen existed at roughly one part per four thousand.

The trio found it. The spectrum showed faint lines shifted from ordinary hydrogen, corresponding to an isotope with twice the nuclear mass. Urey named it deuterium, from the Greek deuteros meaning 'second'—denoting the two particles in its nucleus (one proton, one neutron) versus ordinary hydrogen's single proton.

Urey, Murphy, and Brickwedde submitted their paper to Physical Review in April 1932. Just two years later, Urey received the 1932 Nobel Prize in Chemistry—an extraordinarily rapid recognition reflecting the discovery's importance. He famously declined to attend the Stockholm ceremony so he could be present at the birth of his daughter Mary Alice.

Deuterium proved transformative across multiple fields. Combined with oxygen, it forms 'heavy water' (D2O), which became crucial as a neutron moderator in nuclear reactors. In biology, deuterium-labeled compounds trace metabolic pathways through living tissues. Most significantly, deuterium fusion (combining deuterium nuclei to form helium) releases enormous energy—the reaction powering hydrogen bombs and the eventual promise of fusion power.

Urey founded isotopic chemistry at Columbia, a field that reshaped understanding of reaction mechanisms, metabolic processes, and planetary formation. The heaviest isotope of the lightest element opened an entirely new branch of science.