- 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 of hydrogen
Examples from the Web for hydrogen
From that, they extracted the ratio of the number of deuterium atoms to the number of hydrogen atoms.
They found that there are roughly 1,900 hydrogen atoms for each deuterium atom in the water on Comet 67P.
Deuterium is an isotope of hydrogen containing a proton and neutron in its nucleus, while normal hydrogen has only a proton.
Jupiter and its cousins, by contrast, are mostly made of hydrogen and hydrogen compounds.
Most of the atoms in a newborn star system are hydrogen, which is the lightest chemical element.
Hydrogen is the lightest and consequently the most buoyant of all known gases.Flying Machines
W.J. Jackman and Thos. H. Russell
There was a background sound of hydrogen bombs, heard mutely.Now We Are Three
Joe L. Hensley
Carbon will combine with hydrogen, but will drop it if it can get oxygen.The Machinery of the Universe
Amos Emerson Dolbear
Do you think you can get hydrogen from our coal and make illuminating gas?
There was indeed an incalculable quantity of hydrogen at hand.
- 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°CSee also deuterium, tritium
- (as modifier)hydrogen bomb
Word Origin and History for hydrogen
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.
- 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.
- 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.