Isotopes of Helium
List of known isotopes of the element Helium.
| Isotope | t½ | % | Spin/parity | Radius | Isotopic mass | Discovery |
|---|---|---|---|---|---|---|
| 3He | stab. | 2·10-4 ±2·10-4 % | 1/2+ | 1.966 ±0.003 fm | 3.016·106 ±6·10-5 keV/c2 | 1934 |
| 4He | stab. | 99.99 ±2·10-4 % | 0+ | 1.675 ±0.0028 fm | 4.002·106 ±1.6·10-4 keV/c2 | 1908 |
| 5He | 0.648 MeV | syn. | 3/2- | — | 5.012·106 ±21.47 keV/c2 | 1937 |
| 6He | 806.7 ±15 ms | syn. | 0+ | 2.066 ±0.0111 fm | 6.018·106 ±0.057 keV/c2 | 1936 |
| 7He | 150 ±20 keV | syn. | (3/2)- | — | 7.027·106 ±8.115 keV/c2 | 1967 |
| 8He | 119.1 ±12 ms | syn. | 0+ | 1.923 ±0.0306 fm | 8.033·106 ±0.095 keV/c2 | 1965 |
| 9He | stab. | syn. | 1/2+ | — | 9.043·106 ±50.25 keV/c2 | 1987 |
| 10He | 300 ±200 keV | syn. | (0+) | — | 1.005·107 ±99.67 keV/c2 | 1994 |
3HeHelium-3
| Classification | z: 2; n: 1; m: 3 |
|---|---|
| Half life | stable nuclide |
| Natural abundance | 2·10-4 ±2·10-4 % |
| Spin/parity | 1/2+ |
| Discovery | 1934 |
| Mass excess | 14,930 ±6·10-5 keV |
| Binding energy | 2,572 ±1.5·10-4 keV |
| Single-particle energy | 5,493 ±1·10-4 keV |
| Q value for electron capture | -18.6 keV |
| β⁻ decay energy | -13,740 ±2,000 keV |
| Magnetic dipole moment | -2.128 ±2.999·10-8 μN |
4HeHelium-4
| Classification | z: 2; n: 2; m: 4 |
|---|---|
| Half life | stable nuclide |
| Natural abundance | 99.99 ±2·10-4 % |
| Spin/parity | 0+ |
| Discovery | 1908 |
| Mass excess | 2,424 ±1.5·10-4 keV |
| Binding energy | 7,073 ±2·10-4 keV |
| Single-particle energy | 19,810 ±2·10-4 keV |
| Neutron separation energy | 20,570 ±5·10-4 keV |
| Q value for electron capture | -22,200 ±100 keV |
| β⁻ decay energy | -22,900 ±212.1 keV |
| β⁻ decay energy with neutron | -34,320 ±2,000 keV |
5HeHelium-5
| Classification | z: 2; n: 3; m: 5 |
|---|---|
| Half life | 0.648 MeV |
| Natural abundance | synthetic nuclide |
| Spin/parity | 3/2- |
| Decay modes | neutron emission |
| Discovery | 1937 |
| Mass excess | 11,230 ±20 keV |
| Binding energy | 5,512 ±4 keV |
| Single-particle energy | 20,670 ±101.9 keV |
| Neutron separation energy | -735 ±20 keV |
| Q value for electron capture | -21,670 ±91.65 keV |
| β⁻ decay energy | -447.7 ±53.85 keV |
| β⁻ decay energy with neutron | -22,170 ±213 keV |
6HeHelium-6
| Classification | z: 2; n: 4; m: 6 |
|---|---|
| Half life | 806.7 ±15 ms |
| Natural abundance | synthetic nuclide |
| Spin/parity | 0+ |
| Decay modes | β⁻ decay |
| Discovery | 1936 |
| Mass excess | 17,590 ±0.053 keV |
| Binding energy | 4,878 ±0.0089 keV |
| Single-particle energy | 22,580 ±89.44 keV |
| Neutron separation energy | 1,710 ±20 keV |
| Q value for electron capture | -24,290 ±254.1 keV |
| β⁻ decay energy | 3,505 ±0.0532 keV |
| β⁻ decay energy with neutron | -2,159 ±50 keV |
7HeHelium-7
| Classification | z: 2; n: 5; m: 7 |
|---|---|
| Half life | 150 ±20 keV |
| Natural abundance | synthetic nuclide |
| Spin/parity | (3/2)- |
| Decay modes | neutron emission |
| Discovery | 1967 |
| Mass excess | 26,070 ±7.559 keV |
| Binding energy | 4,123 ±1.079 keV |
| Single-particle energy | 23,090 ±254.2 keV |
| Neutron separation energy | -409.8 ±7.559 keV |
| Q value for electron capture | -23,070 ±1,004 keV |
| β⁻ decay energy | 11,160 ±7.559 keV |
| β⁻ decay energy with neutron | 3,914 ±7.559 keV |
8HeHelium-8
| Classification | z: 2; n: 6; m: 8 |
|---|---|
| Half life | 119.1 ±12 ms |
| Natural abundance | synthetic nuclide |
| Spin/parity | 0+ |
| Decay modes | β⁻ decay; β⁻ decay with neutron emission |
| Discovery | 1965 |
| Mass excess | 31,600 ±0.089 keV |
| Binding energy | 3,924 ±0.0111 keV |
| Single-particle energy | 24,810 ±1,004 keV |
| Neutron separation energy | 2,534 ±7.56 keV |
| β⁻ decay energy | 10,660 ±0.1005 keV |
| β⁻ decay energy with neutron | 8,631 ±0.0887 keV |
9HeHelium-9
| Classification | z: 2; n: 7; m: 9 |
|---|---|
| Half life | stable nuclide |
| Natural abundance | synthetic nuclide |
| Spin/parity | 1/2+ |
| Discovery | 1987 |
| Mass excess | 40,930 ±46.81 keV |
| Binding energy | 3,349 ±5.201 keV |
| Neutron separation energy | -1,255 ±46.81 keV |
| β⁻ decay energy | 15,980 ±46.81 keV |
| β⁻ decay energy with neutron | 11,910 ±46.81 keV |
10HeHelium-10
| Classification | z: 2; n: 8; m: 10 |
|---|---|
| Half life | 300 ±200 keV |
| Natural abundance | synthetic nuclide |
| Spin/parity | (0+) |
| Decay modes | neutron emission |
| Discovery | 1994 |
| Mass excess | 49,190 ±92.84 keV |
| Binding energy | 2,995 ±9.284 keV |
| Neutron separation energy | -190.1 ±103.9 keV |
| β⁻ decay energy | 16,140 ±93.71 keV |
| β⁻ decay energy with neutron | 16,170 ±92.84 keV |