Helium: Difference between revisions
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imported>Howard J. Wilk (Made consistent with other noble gases.) |
imported>Mark Widmer (Added Isotopes section) |
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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. | 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. | ||
==Isotopes== | |||
The helium atom has two stable [[isotope]]s, <sup>3</sup>H and <sup>4</sup>He. | |||
Revision as of 20:49, 12 November 2020
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Helium is a chemical element, having the chemical symbol He. Its atomic number (the number of protons) is 2. It has a standard atomic weight of 4.002602 g•mol −1, and is typically found as a gas in its elemental form.
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.
Isotopes
The helium atom has two stable isotopes, 3H and 4He.