What Is Deuterium? Facts and Uses

Deuterium Facts
Deuterium is an isotope of hydrogen. Each atom has one proton and one neutron.

Deuterium is the hydrogen isotope that has one proton and one neutron in its atomic nucleus. In contrast, most hydrogen is the isotope called protium, which has one proton and no neutrons. Here is a collection of deuterium facts, including whether it’s radioactive, its history, its uses, and its sources.

Is Deuterium Radioactive?

Deuterium, like protium, is a stable isotope. In other words, it is not radioactive. The only radioactive hydrogen isotope is tritium.


Although scientists were aware of stable isotopes prior to the discovery of deuterium, they did not think hydrogen could have any isotopes. The reason is that the neutron had not yet been discovered, so researchers thought isotopes differed by their number of protons and something they called nuclear electrons. By this reasoning, hydrogen could not have isotopes because the nucleus could only contain one proton. So, the discovery of deuterium (and tritium) came as a bit of a shock and completely changed the understanding of isotopes.

Harold Urey discovered deuterium in 1931. He and his collaborator, Ferdinand Brickwedde, distilled the isotope from liquid hydrogen using the low-temperature physics lab at the National Bureau of Standards in Washington, D.C. They concentrated the isotope sufficiently that spectroscopy definitively showed it had an atomic mass of 2. His work earned him the 1934 Nobel Prize in Chemistry.


The element hydrogen is unique in that each of its isotopes have their own names. Deuterium gets its name from the Greek word deuteros, which means “second,” combined with the –ium suffix for an element. The name refers to the second nucleon in the nucleus.

Urey named protium, deuterium, and tritium. As the discoverer of the isotopes, this was his right. However, some scientists resisted the names. For example, Ernest Rutherford felt deuterium should be named “diplogen,” from the Greek word diploos (“double”). Rutherford proposed the deuterium nucleus be called a “diplon” rather than a “deuteron” or “deuton.”

Deuterium Properties

Deuterium displays several interesting properties:

Ionized Deuterium
Normally, deuterium is colorless. When ionized it emits a characteristic pink glow. (photo: Bencbartlett)
  • Both deuterium and tritium form stronger chemical bonds than ordinary hydrogen (protium).
  • Deuterium has a significantly higher triple point, boiling point, vapor pressure, heat of fusion, and heat of vaporization than ordinary hydrogen.
  • Deuterium gas is colorless. However, it emits a characteristic pink glow when ionized.
  • The stronger bonds mean heavy water is about 10.6 times more dense than regular water (1.624 g/cm3). Heavy water ice sinks in regular water, although it floats in heavy water.
  • Heavy water is also more viscous than ordinary water. (12.6 μPa·s at 300 K).

More Deuterium Facts

  • Deuterium is indicated by the symbols D or 2H. Sometimes its called heavy hydrogen.
  • Deuterium is much less abundant than protium. It accounts for just 0.0156% of natural hydrogen.
  • The deuterium nucleus is called a deuteron or deuton.
  • Deuterium is one of only five stable isotopes that has both an odd number of protons and an odd number of neutrons. Usually, doubly-odd atoms are unstable and undergo via beta decay.
  • Deuterium exists on other planets within the solar system and within other stars. The gas giants of the solar system contain roughly the same deuterium concentration as one another.
  • The natural abundance of deuterium varies according to its source.
  • Deuterium (like protium) becomes a liquid metal under extreme pressure.
  • The antimatter counterpart to a deuteron is the antideuteron, which consists of an antiproton and antineutron. Antimatter deuterium is called antideuterium and consists of an antideuteron and positrons.

Health Effects

Humans aren’t exposed to heavy hydrogen (D2), but scientists know a great deal about the effects of heavy water (D2O) on biological system.

Ordinary water always contains trace amounts of deuterium, so ingesting a bit of the isotopes is normal. In fact, you can drink a bit of heavy water will no ill effects. It’s even used in some medical diagnostic tests. Algae and bacteria can live in pure heavy water, although they grow more slowly. Humans and other animals experience heavy water toxicity when heavy water accounts for about 20% of body weight. Eventually, heavy water disrupts mitosis enough to cause death. It’s interesting to note heavy water toxicity affects cancer cells more adversely than it does healthy cells.

Yet, deuterated drugs offer many potential benefits. Deuterium helps protect certain nutrients from oxidative damage. It stabilizes live vaccines, such as the oral poliovirus vaccine. Deuterated drugs reduce the genotoxicity of cancer drugs. Because deuterium binds to carbon more strongly than regular hydrogen, deuterated drugs may last longer before they are metabolized. Deuterium lengths the circadian rhythm clock. Heavy water protects mice from gamma radiation.

Deuterium Uses

Deuterium has several uses:

  • Deuterium finds use in heavy water moderated fission reactors, usually has heavy water, to slow neutrons without absorbing too many of them.
  • Most fusion reactor designs involve deuterium, often with tritium.
  • Nuclear magnetic resonance (NMR) imaging uses deuterium as a solvent because its nuclear spin properties make its signal easy to filter out.
  • Neutron scattering techniques use deuterium to reduce scattering noise in experiments.
  • Deuterium is a stable isotopic tracer that is detectable using infrared spectrometry or mass spectrometry.
  • Deuterated drugs act differently from drugs made using normal hydrogen, offering a host of medical possibilities.

Sources of Deuterium

Most of the deuterium found today formed during the Big Bang. Although it’s possible to make deuterium using a nuclear reactor, it’s not cost-effective. So, most deuterium comes from separating naturally-occurring heavy water from regular water.


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