Deuteron mass
| Value | 3.3435837768e-27 kg |
| Status | Measured: ± 1.00e-36 kg (3.0e-10 relative) |
| Source | CODATA 2022 |
| Categories | Universal & Atomicnuclearatomic |
| microgram | 3.3435838e-18 μg |
| milligram | 3.3435838e-21 mg |
| gram | 3.3435838e-24 g |
| kilogram | 3.3435838e-27 kg |
| metric tonne | 3.3435838e-30 t |
| ounce | 1.1794145e-25 oz |
| pound | 7.3713404e-27 lb |
| stone | 5.2652432e-28 st |
| US short ton | 3.6856702e-30 ton |
| grain | 5.1599383e-23 gr |
| unified atomic mass unit (dalton) | 2.0135532 u |
Learning zone
Urey found deuterium in 1931 by distilling liquid hydrogen and looking for a shifted Balmer line. The deuteron is the simplest bound nucleus and the standard test of the nuclear force: it has just one bound state, no excited states, and a binding energy of only 2.224 MeV — one tenth the binding per nucleon of helium-4, and so weak that a single gamma ray above 2.224 MeV photodisintegrates it.
The mass shows the deficit directly: a proton plus a neutron is 1.007 276 + 1.008 665 = 2.015 941 u, while the deuteron is 2.013 553 u, short by 0.002 388 u = 2.224 MeV/c². Deuterium's practical uses trade on the extra neutron rather than the binding: D₂O moderates neutrons without absorbing them, deuterated solvents keep NMR spectra clean, and D-T fusion is the reaction every tokamak is built around.