Helium 3
Helium 4
Helium 5 Helium-2: Its nucleus has only two protons.
Helium-5 : is one of the isotopes of helium. Its nucleus consists of two protons and three neutrons. Its half-life is 7.6 × 10 − 22 seconds. Helium-6: The nucleus contains two protons and four neutrons, which is very unstable.
Helium-7: The nucleus contains two protons and five neutrons, which will decay into helium-6, which is very unstable.
Helium-8: The nucleus contains 2 protons and 6 neutrons, which is very unstable.
Helium-9: The nucleus contains 2 protons and 7 neutrons, which is very unstable.
Helium-10: The nucleus contains 2 protons and 8 neutrons, which is very unstable.
Helium isotopes have been widely used in nuclear physics and cryogenic physics, especially in extremely cryogenic research.
Symbol | Z（p） | N（n） | Isotope mass (u) | half life | decay mode | decay product | Nucleus spin | Relative abundance (mole fraction) | Variation of relative abundance (mole fraction) |
|---|
two He | two | zero | 2.015894(2) | ≪ 10 −9 s | p(>99.99%) | two one H | 0+(#) | - | - |
β+( | two H |
three He | two | one | 3.0160293191(26) | stable | 1/2+ | 1.34(3)×10 −6 | 4.6×10 −10 -4.1×10 −5 |
four He | two | two | 4.00260325415(6) | stable | 0+ | 0.99999866(3) | 0.999959-1 |
five He | two | three | 5.01222(5) | 700(30)×10 −24 s | n | four He | 3/2- | - | - |
six He | two | four | 6.0188891(8) | 806.7(15) ms | β-(99.99%) | six Li | 0+ |
β-,α(2.8×10%) | four He , two H |
seven He | two | five | 7.028021(18) | 2.9(5)×10 −21 s [159(28) keV] | n | six He | (3/2)- |
eight He | two | six | 8.033922(7) | 119.0(15) ms | β-(83.1%) | eight Li | 0+ |
β-,n (16.0%) | seven Li |
β-,SF(0.9%) | five He,3 H |
nine He | two | seven | 9.04395(3) | 7(4)×10 −21 s | n | eight He | 1/2(-#) |
ten He | two | eight | 10.05240(8) | 2.7(18)×10 −21 s | 2n | eight He | 0+ |
remarks : The data marked with # represents that it has not been proved by experiments and is only theoretical speculation, while the data enclosed in parentheses represents data uncertainty.
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| Helium stable isotope | |
