What are Isotopes of Hydrogen Atoms? 

To understand isotopes, it's easiest to learn the simplest system. Hydrogen, the most basic nucleus, has received a great deal of attention. Several of the results seen in more complex nuclei can be seen in hydrogen isotopes. An isotope is a nucleus of the same atomic number (Z) but a different atomic mass number (A). The number of neutrons present in the nucleus varies with respect to the isotope. 

Hydrogen has three such isotopes with the same atomic number protium, deuterium, and tritium. How can one tell the difference? All of them share one proton (Z = 1) but vary in the number of neutrons they have. Hydrogen contains no neutrons, whereas deuterium has only one neutron and tritium has two neutrons. 


The mass numbers of hydrogen isotopes are one, two, and three, respectively. As a result, their nuclear codes are 1H, 2H, and 3H. These isotopes atoms have just 1 electron to match the charge of the single proton. Since chemistry is based on protons interacting with electrons, the chemical properties of the isotopes are virtually identical. 

Energy might be emitted as a photon, which is a packet of electromagnetic radiation. Gamma rays which are denoted by the Greek letter gamma, “γ” are photons generated by nuclear processes. Whenever a proton and a neutron interact to form deuterium, the reaction is written as 1n + 1H ®2H + g. In this equation, energy must be balanced. 

Mass could be expressed in atomic mass units (u) or in mega electron-volts separated by the square of the speed of light (MeV)/c2. (E = mc2, u = 931.5 MeV/c2 from Einstein's mass-energy equivalence equation.). The sum of the masses of the proton (1.00728 u) and the neutron (1.00866 u) is 2.01594 u. This is smaller than the deuterium nucleus with a mass of 2.01355 u. 

What happened to the missing mass (0.00239 u)? 

The enticing nuclear force between nucleons has produced a negative nuclear potential energy–the binding energy EB–which is linked to the lost mass, D m. (the difference between the two masses). The photon emitted during the deuterium formation process has the energy of 2.225 MeV, which is equal to 0.00239 u, which is needed to split the proton and neutron back into unbound particles. Nuclear decay photons have higher energy than photons generated by atomic processes. 

Whenever a neutron is added to deuterium to form tritium, 1n + 2H® 3H+ g, a greater quantity of power is given out–6.2504 MeV. The higher collaborating energy of tritium relative to deuterium demonstrates that the nuclear potential energy does not increase in a linear fashion with both the inclusion of nucleons (the overall binding energy is roughly proportional to A). The binding energy per unit nucleon increases as protons and neutrons are introduced to form more substantial nuclei, reaching a peak of about 8 MeV per nucleon for about A = 60, after which the average binding energy per nucleon gradually falls up to one of the most powerful nuclei, where it is approximately 7 MeV. 

" Isotopes of Hydrogen atom "

Protium (Hydrogen-1) 

1H atomic mass 1.007825032241 is the most abundant hydrogen isotope, accounting for more than 99.98 percent of all hydrogen isotopes. Since this isotope's nucleus consists of just one proton, it is assigned the formal name protium. Since the protons have not been found to decay, hydrogen-1 is called a stable isotope. According to certain grand unified theories suggested in the late 1970s, proton decay occurrence happens with a half-life of 1028 to 1036 years. 

Deuterium (Hydrogen-2) 

The other stable hydrogen isotope, with an atomic mass of 2.01410177811, is known as deuterium which has 1 proton and 1 neutron within its nucleus. A deuteron is the nucleus of deuterium. Deuterium makes up 0.0026–0.0184 percent (by quantity and by not mass) of hydrogen quantity found on Earth, with an even much lower percentage present in hydrogen gas samples and the higher enrichment contained in seawater. Deuterium is found to be not radioactive and poses no major toxicity risk. Heavy water is water that is enriched in compounds that contain deuterium rather than protium. In chemical tests and in solvents for 1H-NMR spectroscopy, deuterium and its compounds are utilized as a non-radioactive name. Heavy water, D2O is actively utilized in nuclear reactors for the purpose of neutron moderators and coolants.

Tritium (Hydrogen-3) 

3.01604928199(Da)tritium, has 1 proton and 2 neutrons in its nucleus. It is radioactive, decaying with a half-life of 12.32 years into helium-3. Formalized paraphrase Tritium traces exist spontaneously as a result of cosmic ray interactions with greenhouse gases. Tritium has also been found in nuclear weapons tests. Tritium was sometimes routinely used as a radiolabel in chemical and biological labeling tests, although it has been less widespread in recent years. D-T nuclear fusion uses tritium and deuterium as the primary reactants, liberating energy by mass loss when the 2 nuclei meet and fuse at extreme temperatures. 

" Representation of deuterium"

Radioactivity of Isotopes of Hydrogen 

A molecule is considered to be radioactive when it possesses unstable nuclei. Radioactive decay is a phenomenon that states the degradation of a molecule through loss of energy over a period of time for a single atom. The half-life of an atom indicates the overall decay rate of an atom. The half-life of the isotopes of Hydrogen is 12.32 years. The most stable radioisotope of hydrogen is tritium which implies that the other isotopes are more radioactive than tritium.

" radioactive hydrogen"

Synthetic Isotopes of Hydrogen 

The synthetic isotopes of hydrogen are H4, H5, H6 and H7. They are also known as the radioactive isotopes of hydrogen. These isotopes are synthesized by performing radioactive reactions on the naturally occurring isotopes of hydrogen. Due to the increasing number of neutrons in their nucleus their stability is quite low compared to the naturally occurring isotopes and thus the half-life of these isotopes are also small. 


Hydrogen isotope identification provides for the traceless and straightforward insertion of extra mass or a radioactive marker into an organic molecule with little to no alteration in its chemical composition, physical properties, or biological behavior. The use of deuterium labelling isotope is analogues to specific mass spectrometric MS-patterns produced from mixtures of biologically relevant molecules greatly simplifies research. 

These approaches are now offering extraordinary amounts of expertise across a diverse and ever-expanding variety of applications in the life sciences and beyond. Tritium (3H) in particular has seen increased use, especially in pharmaceutical drug discovery. 

Context and Applications 

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for       

  • Bachelor of Science (Physics) 
  • Bachelor of Science (Chemistry) 

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