He
Helium-4
Protons (Z)
2
Neutrons (N)
2
Mass number
4
Half-Life
Stable
Abundance
99.9998%
Mass
4.003 u
Mass Excess
2,424.916 keV
Spin
0+
Discovered
1908
Binding energy per nucleon
7,074 keV
Neutron separation energy
20,578 keV
Proton separation energy
19,814 keV
Decay Mode
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