Deuterium Facts

What is deuterium? Here's a look at what deuterium is, where you might find it, and some of the uses of deuterium.

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Is Deuterium Radioactive?

By Anne Marie Helmenstine, Ph.D.

Deuterium Definition

Hydrogen is unique in that it has three isotopes which are named. Deuterium is one of the isotopes of hydrogen. It has one proton and one neutron. In contrast, the most common isotope of hydrogen, protium, has one proton and no neutrons. Because deuterium contains a neutron, it is more massive or heavier than protium, so it is sometimes called heavy hydrogen. There's a third hydrogen isotope, tritium, which may also be called heavy hydrogen because each atom contains one proton and two neutrons.

Deuterium Facts

• The chemical symbol for deuterium is D. Sometimes the symbol ²H is used.
• Deuterium is a stable isotope of hydrogen. In other words, deuterium is not radioactive.
• The natural abundance of deuterium in the ocean is approximately 156.25 ppm, which is one atom in 6,400 of hydrogen. In other words, 99.98% of hydrogen in the ocean is protium and only 0.0156% is deuterium (or 0.0312% by mass).
• The natural abundance of deuterium is slightly different from one water source to another.
• Deuterium gas is one form of naturally occurring pure hydrogen. It's chemical formula is written as either ²H₂ or as D₂. Pure deuterium gas is rare. It's more common to find deuterium bonded to a protium atom to form hydrogen deuteride, which is written as HD or ¹H²H.
• The name for deuterium comes from the Greek word deuteros, which means "second". This is in reference two the two particles, a proton, and a neutron, which make up the nucleus of a deuterium atom.
• A deuterium nucleus is termed a deuteron or deuton.
• Deuterium is used as a tracer, in nuclear fusion reactors and to slow down neutrons in heavy water moderated fission reactors.
• Deuterium was discovered in 1931 by Harold Urey. He used the new form of hydrogen to produce samples of heavy water. Urey won the Nobel Prize in 1934.
• Deuterium behaves differently from normal hydrogen in biochemical reactions. While it's not deadly to drink a small amount of heavy water, for example, ingesting a large quantity can be lethal.
• Deuterium and tritium form stronger chemical bonds than the protium isotope of hydrogen. Of interest to pharmacology, it's harder to remove carbon from deuterium. Heavy water is more viscous than ordinary water and is approximately 10.6 percent denser.
• Deuterium is one of only five stable nuclides that has an odd number of both protons and neutrons. In most atoms, odd numbers of protons and neutrons are unstable with respect to beta decay.
• The presence of deuterium has been confirmed on other planets in the solar system and in the spectra of stars. The outer planets have roughly the same deuterium concentration as each other. It is believed most of the deuterium present today was produced during the Big Bang nucleosynthesis event. Very little deuterium is seen in the Sun and other stars. Deuterium is consumed in stars at a faster rate than it is produced via the proton-proton reaction.
• Deuterium is made by separating naturally-occurring heavy water from a large volume of natural water. Deuterium could be produced in a nuclear reactor, but the method is not cost-effective.