He
Гелій
Z 2 4,003 г/мольБлагородний газ
| 4He | 2 | 4,0026 | 2 424,916 | 99,9998% | Стабільний | 0+ | --- | 1908 |
| 3He | 1 | 3,016 | 14 931,219 | 0,0002% | Стабільний | 1/2+ | --- | 1934 |
| 5He | 3 | 5,0121 | 11 231,0 | --- | 602,0 йс | 3/2- | n→4He(100%) | 1937 |
| 6He | 4 | 6,0189 | 17 592,1 | --- | 806,92 мс | 0+ | β⁻→6Li(~100%) β⁻→4He(2,78е-4%) | 1936 |
| 7He | 5 | 7,028 | 26 073,0 | --- | 2,51 зс | (3/2-) | n→6He(100%) | 1967 |
| 8He | 6 | 8,0339 | 31 609,68 | --- | 119,5 мс | 0+ | β⁻→8Li(83,1%) β⁻n→7Li(16%) β⁻→5He(0,9%) | 1965 |
| 9He | 7 | 9,044 | 40 940,0 | --- | 2,5 зс | (1/2+) | n→8He(100%) | 1987 |
| 10He | 8 | 10,0528 | 49 200,0 | --- | 260,0 йс | 0+ | n→8He(100%) | 1994 |