Difference Between Deuterium and Tritium

The key difference between deuterium and tritium is that deuterium nucleus has one neutron whereas tritium nucleus has two neutrons.

Hydrogen is the first and smallest element in the periodic table, which we denote as H. It has one electron and one proton. We can categorize it under group 1 and period 1 in the periodic table because of its electron configuration: 1s1. Hydrogen can take up an electron to form a negatively charged ion, or can easily donate the electron to produce a positively charged proton. If not, it can share the electron to make covalent bonds. Because of this ability, hydrogen is present in a large number of molecules, and it is a highly abundant element in the earth. Hydrogen has three isotopes as protium-1H (no neutrons), deuterium-2H (one neutron) and tritium- 3H (two neutrons). Protium is the most abundant among these three, having about 99% relative abundance.

CONTENTS

1. Overview and Key Difference
2. What is Deuterium 
3. What is Tritium
4. Side by Side Comparison – Deuterium vs Tritium in Tabular Form
5. Summary

What is Deuterium?

Deuterium is one of the isotopes of hydrogen. It is a stable isotope with 0.015% natural abundance. There is a proton and a neutron in the nucleus of deuterium. Therefore, its mass number is two, and the atomic number is one. We call this isotope as heavy hydrogen and is shown as 2H. However, most commonly, we represent it with D.

Deuterium can exist as a diatomic gaseous molecule with the chemical formula D2. However, the possibility of joining two D atoms in nature is low due to the lower abundance of it. Therefore, this isotope mostly binds with a 1H atom making a gas -HD (hydrogen deuteride). Also, two deuterium atoms can bind with oxygen to form the water analog D2O, which we call heavy water.

Moreover, molecules with deuterium show different chemical and physical properties than the hydrogen analog of them. For example, it can exhibit a kinetic isotope effect. Furthermore, deuterated compounds show characteristic differences in NMR, IR and mass spectroscopy; therefore, we can identify it using those methods. Also, deuterium has a spin of one. Therefore, in NMR, the coupling of this isotope gives a triplet. Moreover, it absorbs a different IR frequency than hydrogen in IR spectroscopy. Due to the large mass difference, in mass spectroscopy, deuterium can be distinguished from hydrogen.

What is Tritium?

Tritium is the isotope of hydrogen whose mass number is three. Therefore, the nucleus of tritium has one proton and two neutrons. It only exists in trace amount in nature due to its radioactivity. Because of this reason, it has to be produced artificially for practical usage.

Tritium is a radioactive isotope (this is the only radioactive isotope of hydrogen). It has a half-life of 12 years, and it decays by emitting a beta particle to produce helium-3. The atomic mass of this isotope is 3.0160492. Besides, it exists as a gas (HT) at standard temperature and pressure. Also, it can form the oxide (HTO), which we call “tritiated water.” Tritium is useful in making nuclear weapons and as a tracer in biological and environmental studies.

What is the Difference Between Deuterium and Tritium?

Deuterium and tritium are two isotopes of hydrogen. The key difference between deuterium and tritium is that the deuterium nucleus has one neutron whereas tritium nucleus has two neutrons. Furthermore, the mass number of deuterium is 2.0135532 while the mass number of tritium is 3.0160492. So, this is another significant difference between deuterium and tritium.

Moreover, a further difference between deuterium and tritium is that the deuterium is a stable isotope and we can find it in nature whereas tritium is a radioactive isotope that we cannot find it in nature. However, we can produce it artificially for practical usage.

Summary – Deuterium vs Tritium

Deuterium and tritium are isotopes of the chemical element hydrogen. The key difference between deuterium and tritium is that Deuterium nucleus has one neutron whereas tritium nucleus has two neutrons. Moreover, tritium is radioactive while deuterium is a stable isotope.

Reference:

1. Helmenstine, Anne Marie, Ph.D. “Deuterium Facts.” ThoughtCo, Apr. 2, 2019, Available here.

Image Courtesy:

1. “Blausen 0527 Hydrogen-2 Deuterium” By BruceBlaus – Own work (CC BY 3.0) via Commons Wikimedia
2. “Protium deuterium tritium” By Lamiot for french version, from Dirk Hünniger – self, translation from Dirk Hünniger (german wikipedia) (CC BY-SA 3.0) via Commons Wikimedia