Helium (He) is a colorless, odorless, tasteless, non-toxic, in the periodic table it's atomic number is 2. Its boiling and melting points are the lowest among the elements and it exists only as agas except in extreme conditions. Helium is named for the Sun since it was first detected as a new element in 1868 by a French astronomer, as an unknown yellowspectral line signature in light from a solar eclipse.
Helium is the second most abundant and second lightest element in the known universe, and is one of the elements believed to have been created in the Big Bang. In the modern universe almost all new helium is created as a result of the nuclear fusion of hydrogen in stars. On Earth helium is rare, and almost all of that which exists was created by the radioactive decay of much heavier elements (alpha particles are helium nuclei). After its creation, part of it was trapped with natural gas in concentrations up to 7% by volume, from which it is extracted commercially by fractional distillation. Large reserves of helium have been found in the natural gas fields of the United States (the largest supplier) but helium is known in gas reserves of a few other countries.
Helium is used in cryogenics, in deep-sea breathing systems, in helium dating, to cool superconducting magnets (the largest liquid helium use is presently MRI machines), for inflating balloons, for providing lift in airships and as a protective gas for many industrial uses (such as arc welding and growing silicon wafers).
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