Helium: Difference between revisions
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imported>David Yamakuchi mNo edit summary |
imported>Mark Widmer m (Minor revision to opening paragraph.) |
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'''Helium''' is a [[Chemical elements|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 [[Atomic mass#Standard atomic weights of the elements|standard atomic weight]] of 4.002602 g/mol. | |||
Helium is a monatomic noble gas. At a [[pressure]] of 101.325 k[[Pascal (unit)|Pa]], it has a [[boiling point]] of -268.93 °[[Celsius (unit)|C]], and a [[melting point]] of -272.2 °C. It is of relatively low density--see [[Benchmark_quantities#Density|Benchmark quantities]]. | |||
==Isotopes== | |||
The helium atom has two stable [[isotope]]s, <sup>3</sup>H and <sup>4</sup>He. | |||
Latest revision as of 16:58, 1 January 2021
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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.