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Physical Chemistry

Periodic Graphics

Periodic Graphics: The science and uses of deuterium

Chemical educator and Compound Interest blogger Andy Brunning describes how deuterium and hydrogen differ and how scientists use the isotope.

by Andy Brunning, special to C&EN
November 28, 2021 | A version of this story appeared in Volume 99, Issue 43


A two-column infographic on the science and uses of deuterium.
Deuterium is a stable isotope of hydrogen discovered in 1931. Isotopes are atoms of an element made up of the same number of protons and electrons but a different number of neutrons. A diagram shows that hydrogen has one proton and one electron, while deuterium has one proton, one electron, and one neutron.
Hydrogen and deuterium undergo the same reactions, but the rates of reaction can differ because of deuterium’s heavier mass, a phenomenon called the kinetic isotope effect. Deuterium also behaves differently in physical processes. Heavy water has slightly different physical and chemical properties from normal water. A table shows some of these properties: heavy water has a slightly higher density, melting point, and boiling point than normal water.
Heavy water is used in some nuclear reactors as a moderator, slowing down neutrons so they propagate nuclear chain reactions more effectively. Deuterium is also used in prototype fusion reactors.
In hydrogen nuclear magnetic resonance spectroscopy, deuterated solvents stop hydrogen-containing solvents from producing peaks that swamp out signals from the target molecule. Additionally, deuterium can replace a hydrogen in some functional groups, like alcohols, making their peaks disappear.
Replacing hydrogens in some drug molecules with deuteriums can slow the compound’s metabolism in the body. The first deuterated drug, deutetrabenazine, was approved by the US Food and Drug Administration in 2017.
Scientists can use the ratio of deuterium to hydrogen in ice core samples to calculate past temperatures. Heavy water molecules evaporate less easily, so the 2H:1H ratio can be used as a thermometer.

Credit: Andy Brunning/Compound Interest

To download a pdf of this article, visit

References used to create this graphic:

Halford, Bethany. “Deuterium Switcheroo Breathes Life into Old Drugs.” Chemical & Engineering News, July 4, 2016.

Krumbiegel, Peter. “Large Deuterium Isotope Effects and Their Use: A Historical Review.” Isot. Environ. Health Stud. 2011, DOI: 10.1080/10256016.2011.556725.

O’Leary, Dan. “The Deeds to Deuterium.” Nat. Chem. 2012, DOI: 10.1038/nchem.1273.

Wothers, Peter. “Heavy Water,” Dec. 13, 2011, in Chemistry World, podcast.

A collaboration between C&EN and Andy Brunning, author of the popular graphics blog Compound Interest

To see more of Brunning’s work, go to To see all of C&EN’s Periodic Graphics, visit



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