Difference Between Deuterium and Hydrogen

Deuterium vs Hydrogen

Atoms of the same element can be different. These different atoms of the same element are called isotopes. They are different from each other by having different numbers of neutrons. Since the neutron number is different, their mass number also differs. Elements may have several isotopes. The nature of each isotope contributes to the nature of an element. Deuterium is a hydrogen isotope and the following article describes their differences.


Hydrogen is the first and the smallest element in the periodic table, which is denoted as H. It has one electron and one proton. It is categorized 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 or 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 named as protium-1H (no neutrons), deuterium-2H (one neutron) and tritium- 3H (two neutrons).  Protium is the most abundant among three having about 99% relative abundance. Hydrogen exists as a diatomic molecule (H2) in the gas phase, and it is a colorless, odorless gas. Furthermore, hydrogen is an extremely flammable gas, and it burns with a pale blue flame. Hydrogen, under normal room temperature, is not very reactive. However, in high temperatures, it can react fast. H2 is in the zero oxidation state; therefore, it can act as a reducing agent, to reduce metal oxides or chlorides and release metals. Hydrogen is used in chemical industries such as for ammonia production in Haber process. Liquid hydrogen is used as a fuel in rockets and vehicles.


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, the mass number of it is two, and the atomic number is one. This is also known as the heavy hydrogen. Deuterium is shown as 2H. But most commonly it is represented 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 deuterium. Therefore, mostly deuterium is bonded to a 1H atom making a gas called HD (hydrogen deuteride).  Two deuterium atoms can bind with an oxygen to form the water analog D2O, which is also known as heavy water. Molecules with deuterium show different chemical and physical properties than the hydrogen analog of them. For example, deuterium can exhibit kinetic isotope effect. Deuterated compounds show characteristic differences in NMR, IR and mass spectroscopy, therefore, can be identified using those methods. Deuterium has a spin of one. So in NMR, deuterium coupling gives a triplet. It absorbs a different IR frequency than hydrogen in IR spectroscopy. Due to large mass difference, in mass spectroscopy, deuterium can be distinguished from hydrogen.


What is the difference between Hydrogen and Deuterium?

• Deuterium is an isotope of hydrogen.

• Compared to other hydrogen isotopes, deuterium has a mass number of two (one neutron and one proton in the nucleus).

• Atomic weight of hydrogen is 1.007947, whereas the mass of deuterium is 2.014102.

• When deuterium is incorporated in molecules instead of hydrogen, certain properties like bond energy and bond length differ.