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hydrogen

[hahy-druh-juh n] /ˈhaɪ drə dʒən/
noun
1.
a colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known elements. Symbol: H; atomic weight: 1.00797; atomic number: 1; density: 0.0899 g/l at 0°C and 760 mm pressure.
Origin
1785-1795
1785-95; < French hydrogène. See hydro-1, -gen
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for hydrogen
  • hydrogen peroxide is a liquid commonly used to fight germs.
  • Over time, this hydrogen leaks out of the steel and into the chamber.
  • The hydrogen could then power hydrogen fuel cells, a type of battery that emits only water.
  • Some support hydrogen as a source of energy for the transportation sector.
  • One of the biggest bumps in the road to the development of fuel-cell cars is detecting hydrogen gas leaks.
  • Five hundred fifty feet of piping were jammed alongside two tanks, one for oxygen and one for hydrogen.
  • The mitochondria of the autistic children also leaked damaging oxygen-rich chemicals such as hydrogen peroxide.
  • The technique gives a rough idea of where an animal lived based on hydrogen atoms contained in the rainwater it drinks.
  • Researchers have discovered a way of bioengineering algae to produce hydrogen.
  • The equipment that was installed included igniters that burn off any hydrogen generated before the gas can explode.
British Dictionary definitions for hydrogen

hydrogen

/ˈhaɪdrɪdʒən/
noun
1.
  1. a flammable colourless gas that is the lightest and most abundant element in the universe. It occurs mainly in water and in most organic compounds and is used in the production of ammonia and other chemicals, in the hydrogenation of fats and oils, and in welding. Symbol: H; atomic no: 1; atomic wt: 1.00794; valency: 1; density: 0.08988 kg/m³; melting pt: –259.34°C; boiling pt: –252.87°C See also deuterium, tritium
  2. (as modifier) hydrogen bomb
Word Origin
C18: from French hydrogène, from hydro- + -gen; so called because its combustion produces water
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for hydrogen
n.

1791, from French hydrogène, coined 1787 by G. de Morveau, Lavoisier, Berthollet, and Fourcroy from Greek hydr-, stem of hydros "water" (see water (n.1)) + French -gène "producing" (see -gen). So called because it forms water when exposed to oxygen. Nativized in Russian as vodorod; in German, it is wasserstoff, "water-stuff." An earlier name for it in English was Cavendish's inflammable air (1767). Hydrogen bomb first recorded 1947; shortened form H-bomb is from 1950.

Online Etymology Dictionary, © 2010 Douglas Harper
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hydrogen in Medicine

hydrogen hy·dro·gen (hī'drə-jən)
n.
Symbol H
A colorless, highly flammable gaseous element, the most abundant in the universe, used in ammonia and methanol synthesis, in the hydrogenation of organic materials, and as a reducing atmosphere. Atomic number 1; atomic weight 1.00797; melting point -259.34°C; boiling point -252.9°C; density at 0°C 0.08988 gram per liter; valence 1.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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hydrogen in Science
hydrogen
  (hī'drə-jən)   
Symbol H
The lightest and most abundant element in the universe, normally consisting of one proton and one electron. It occurs in water in combination with oxygen, in most organic compounds, and in small amounts in the atmosphere as a gaseous mixture of its three isotopes (protium, deuterium, and tritium) in the colorless, odorless compound H2. Hydrogen atoms are relatively electropositive and form hydrogen bonds with electronegative atoms. In the Sun and other stars, the conversion of hydrogen into helium by nuclear fusion produces heat and light. Hydrogen is used to make rocket fuel, synthetic ammonia, and methanol, to hydrogenate fats and oils, and to refine petroleum. The development of physical theories of electron orbitals in hydrogen was important in the development of quantum mechanics. Atomic number 1; atomic weight 1.00794; melting point -259.14°C; boiling point -252.8°C; density at 0°C 0.08987 gram per liter; valence 1. See Periodic Table. See Note at oxygen.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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hydrogen in Culture

hydrogen definition


The lightest chemical element; its symbol is H. Hydrogen normally consists of a single electron in orbit around a nucleus made up of a single proton. It is usually found as a gas and has several uses as a fuel.

Note: Hydrogen atoms are combined to form helium atoms in fusion reactions in stars and in hydrogen bombs, which release huge amounts of energy. Hydrogen also burns rapidly, producing water as it combines with oxygen (see H<sub>8</sub>O and oxidation).
Note: For a time, hydrogen was frequently used to fill blimps and dirigibles because of its extremely low weight. In 1937, however, the hydrogen in the dirigible Hindenburg caught fire, and many of the passengers and crew were killed. Since that time, helium has been widely preferred to hydrogen for use in airships; it is not as buoyant (see buoyancy) or cheap as hydrogen, but, being an inert gas, it does not burn.
Note: Because there is so much hydrogen in stars, it is by far the most abundant element in the universe.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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