Helium-4

Helium-4
General
Symbol4He
Nameshelium-4
Protons (Z)2
Neutrons (N)2
Nuclide data
Natural abundance99.999863% (atmosphere)
Half-life (t1/2)stable
Isotope mass4.002603254 Da
Spin0
Nuclear binding energy28295.7 keV
Isotopes of helium
Complete table of nuclides
Picture of a diffuse gray sphere with grayscale density decreasing from the center. Length scale about 1 Angstrom. An inset outlines the structure of the core, with two red and two blue atoms at the length scale of 1 femtometer.
The helium atom. Depicted are the nucleus (pink) and the electron cloud distribution (black). The nucleus (upper right) in helium-4 is in reality spherically symmetric and closely resembles the electron cloud, although for more complicated nuclei this is not always the case.

Helium-4 (4
He) is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up virtually all the helium on Earth. Its nucleus consists of two protons and two neutrons and is identical to an alpha particle.

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