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Helium-4

Properties and data of the isotope 4He.


Content

 

Helium-4 isotope

See also: list of Helium isotopes.

 

General data

Name of the isotope:Helium-4; He-4Symbol:4He or 42HeMass number A:4 (= number of nucleons)Atomic number Z:2 (= number of protons)Neutrons N:2Isotopic mass:4.0026032541(4) u (atomic weight of Helium-4)Nuclide mass:4.0015061 u (calculated nuclear mass without electrons)Mass excess:2.42492 MeVMass defect:0.0303766419 u (per nucleus)Nuclear binding energy:28.29565967 MeV (per nucleus)
7.07391492 MeV (average binding energy per nucleon)
Separation energy:SN = 20.57762(0) MeV (first neutron)
SP = 19.81386(0) MeV (first proton)
Half-life:stableSpin and parity:
(nuclear angular momentum)
0+Isobaric spin: 0Charge radius:1.67824(83) femtometer fmYear of discovery:1908

 

Parent Nuclides

Direct parent isotopes are: 5He, 5Li, 6Be.

 

Occurrence

Comparison of the natural Helium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

 

Atomic Mass maQuantityHalf-lifeSpin
Helium
Isotopic mixture
4.002602 u100 %
Isotope 4He4.0026032541(4) u99.9998(2) %stable0+
Isotope 3He3.01602932(2) u0.0002(2) %stable1/2+

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 2) and isobaric (same nucleon number A = 4) with Helium-4. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 2Isobar A = 4
13H4H
24He4He
35Li4Li
46Be
57B
68C
79N

 

External data and identifiers

Adopted Levels, Gammas:NuDat 4He

 

Literature and References

[1] - Julian J. Krauth, Karsten Schuhmann, Marwan Abdou Ahmed et al.:
Measuring the α-particle charge radius with muonic helium-4 ions.
In: Nature, 589, 527 - 531, (2021), DOI 10.1038/s41586-021-03183-1.

 


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Last update: 2023-10-06


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