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Helium

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Helium
4.002602(2)



  He
2
1s2
[ ? ] Noble gas:
Properties:
Inert, colorless, odorless, non-toxic, non-flammable gas
Uses:
Cryogenics, welding, inert purging gas, scientific uses

Helium is a chemical element, typically found as a gas in its elemental form. It has the chemical symbol He, atomic number (number of protons) Z = 2, and a standard atomic weight of 4.002602 g/mol.

Helium is a monatomic noble gas. At a pressure of 101.325 kPa, it has a boiling point of -268.93 °C, and a melting point of -272.2 °C. It is of relatively low density--see Benchmark quantities.

Isotopes

The helium atom has two stable isotopes, 3H and 4He.