hydrogen

plural hydrogens

1. uncountablechemistryThe lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.008.

   Our professor then reminded us that a hydrogen ion is merely a proton, and thus we should think about acid-base theory as we consider this problem further.

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   The ignis fatuus or Jack a lantern, ſo frequently alluded to by poets, is ſuppoſed to originate from the inflammable air, or Hydrogene, given up from moraſſes; […]

   1791, [Erasmus Darwin], “Canto I”, in The Botanic Garden; a Poem, in Two Parts. […], London: J[oseph] Johnson, […], →OCLC, part I (The Economy of Vegetation), footnote, page 18

   But my Leech—a leech / Fit to suck blood, with lubricous round rings, / Capaciously expatiative, which make / His little body like a red balloon, / As full of blood as that of hydrogen, / Sucked from men's hearts; […]

   1820, Sophocles, “Œdipus Tyrannus; or, Swellfoot the Tyrant. A Tragedy, in Two Acts. […]”, in Percy Bysshe Shelley, transl., edited by [Mary] Shelley, The Poetical Works of Percy Bysshe Shelley. […], new edition, London: Edward Moxon […], published 1840, →OCLC, Act I, page 184

   Water is the sole product of the combustion of hydrogen gas. For this important fact we are indebted to Mr. [Henry] Cavendish. He demonstrated it by burning oxygen and hydrogen gases in a dry glass vessel, when a quantity of pure water was generated exactly equal in weight to that of the gases which had disappeared.

   1827, Edward Turner, “Section IV. Hydrogen.”, in Elements of Chemistry: Including the Recent Discoveries and Doctrines of the Science, Edinburgh: […] William Tait, […]; and Charles Tait, […], part II (Inorganic Chemistry), page 160

   It was an enormous balloon filled with helium, that elemental gas forged from hydrogen in the nuclear furnace of the stars, first step along the way in the generation of multiplicity and variety of matter in the universe, including our selves and all our thoughts.

   1997, Ian McEwan, chapter 1, in Enduring Love, [United Kingdom]: The Softback Preview, →OCLC, page 3

   1. countablechemistryAn atom of this element.

      Each carbon of the ring has one hydrogen attached except for the fourth one, which is bonded to a substituent.

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      Water occupies an intermediate position and shows tendencies both to add and give up hydrogen, which are nearly balanced. Then, in terms of the Lewis theory, a free pair of electrons on one water molecule might be able to exert sufficient force on a hydrogen held by a pair of electrons on another water molecule to bind the two molecules together.

      1920 July, Wendell M[itchell] Latimer, Worth H. Rodebush, “Polarity and Ionization from the Standpoint of the Lewis Theory of Valence”, in Arthur B. Lamb, editor, The Journal of the American Chemical Society, volume XLII, number 7, Easton, Pa.: Eschenbach Printing Company [for the American Chemical Society], →ISSN, →OCLC, page 1431

      [H]ydrogens are also classified as primary, secondary, or tertiary depending on the type of carbon to which each is bonded. Those attached to primary carbons are classified as primary hydrogens, those on secondary carbons are secondary hydrogens, and those on tertiary carbons are tertiary hydrogens. Hydrogen atoms in a compound can be divided into equivalent sets. Equivalent hydrogens have the same chemical environment. A direct way to determine which hydrogens in a molecule are equivalent is to replace each in turn by a "test atom," as for example a halogen atom.

      1995, William H. Brown, “Alkanes and Cycloalkanes”, in Organic Chemistry, Fort Worth, Tex.; Philadelphia, Pa.: Saunders College Publishing; Harcourt Brace College Publishers, →ISBN, page 62

      The chemical name for Teflon is polyperfluoroethylene, meaning many repeats of ethylene with all its hydrogens replaced with fluorine.

      2014, Theodore Gray, photography by Nick Mann, Molecules: The Elements and the Architecture of Everything, Paperback 2018 Edition, page 48

2. uncountablechemistryMolecular hydrogen (sense 1; symbol H₂), a colourless, odourless and flammable gas at room temperature.

   A large tank of hydrogen constituted most of the bulk of that rocket.

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   [Jacques] Charles was the first to send up a hydrogen balloon, 12 feet in diameter, which rose 3,123 feet, disappeared in the clouds, and fell at the distance of 15 miles.

   1845 February 8, “Balloons”, in Theodore Dwight, Jr., editor, American Penny Magazine, and Family Newspaper, volume I, number 1, New York, N.Y.: Express Office, […], →ISSN, →OCLC, page 12, column 1

   As the tension between the Soviets and the United States increased from 1948 to 1950, the administration took a number of actions that [George Frost] Kennan felt narrowed the possibilities for constructive negotiations between the two nations. These actions included the decisions to build the hydrogen bomb, to maintain American troops in Japan after the formal occupation was over, to create an independent West German state, and to form the North Atlantic Treaty Organization (NATO).

   1991 August, Stanley E. Spangler, “Kennan, Containment, and Carrots”, in Force and Accommodation in World Politics, Maxwell Air Force Base, Ala.: Air University Press, →ISBN, part 1 (Factors Inhibiting Accommodative Diplomacy since World War II), pages 32–33

   To this end the Department of Science and Technology has identified the hydrogen economy and related fuel cell technologies as a "Frontier Science and Technology Area" that could potentially change the innovation course of the country's natural resources, and yield multiple social and economic benefits.

   2005, F. W. Petersen, S. E. T. Bullock, “Sustainable Development Indicators—Some Technological Changes Made in the South African Mining and Resources Sector to Meet the Challenge”, in Roberto C[errini] Villas-Bôas [et al.], editors, A Review on Indicators of Sustainability for the Minerals Extraction Industries, Rio de Janeiro, Brazil: CETEM/CNPq/CYTED, →ISBN, part 2 (Indicators: Some Facts, Exercises and Proposals), page 162

   1. countablechemistryA molecule of this molecular species.

      Synonyms: dihydrogen, E949, hydrogen hydride

3. uncountablechemistrySynonym of protium (“the lightest and most common isotope of hydrogen (sense 1; symbol H, ¹H, or 11H), as contrasted with deuterium and tritium”).

   Both hydrogen and deuterium are present in every glass of water that you drink, but the amount of deuterium is rather small.

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   Hydrogen is generally considered to be electronically the same as deuterium. […] Neutron diffraction experiments by Ferguson, Schindler, Tanaka, and Morita (ref. 4) revealed that, near 50K, some hydrogen had moved from interstitial octahedral sites (0, 0, 1/2; 1/2, 0, 0; …) of the palladium lattice to the tetrahedral sites (1/4, 1/4, 1/4; 3/4, 3/4; …) (O-T transitions).

   1969 September, Dumas A. Otterson, Robert J. Smith, “Introduction”, in Absorption of Hydrogen by Palladium and Electrical Resistivity up to Hydrogen-Palladium Atom Ratios of 0.97 (NASA Technical Note; D-5441), Washington, D.C.: National Aeronautics and Space Administration, →OCLC, page 2

   Synonyms: protium