Isotopes of helium

Isotope data
helium symbol icon

Helium has two isotopes but it consists almost entirely of He-4 with natural He only containing just over 0.0001% of He-3. Thousands of liters of He-3 are used annually in cryogenic applications and He-3 is also used as a neutron counter in nuclear application. He-3 is also applied in magnetic resonance imaging. Helium isotopes can be obtained from Trace Sciences International.

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of helium are listed (including any which occur naturally) below.
Isotope Atomic mass (ma/u) Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
3He 3.016 029 309 7(9) 0.000137 (3) 1/2 -2.127624
4He 4.002 603 2497(10) 99.999863 (3) 0 0

Isotopic abundances of He
In the above picture, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which total 100% for all the naturally occurring isotopes.

Radiosotope data

Further data for naturally occuring isotopes of helium are listed above. This table gives information about some radiosotopes of helium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass Half-life Mode of decay Nuclear spin Nuclear magnetic moment
6He 6.018886 0.807 s β- to 6Li 3/2
8He 8.03392 0.119 s β- to 8Li; β- + n to 7Li 3/2

Sheffield ChemPuter isotope pattern calculator

You can use WebElements to calculate an isotope pattern for an arbitrary chemical formula:

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  • 'Pseudoelements' such as Me, Ph, Cp, and many others are OK
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References

  1. Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
  2. Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]
  3. For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides

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helium atomic number