hydrogen

[hahy-druh-juhn]

noun

1. a colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known elements. H; 1.00797; 1; density: 0.0899 grams/liter at 0°C and 760 millimeters pressure.

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

hydrogen

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 H ₂. 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.

2. See Periodic Table See Note at oxygen

Word History and Origins

Origin of hydrogen¹

First recorded in 1785–95; from the French word hydrogène; hydro- ¹, -gen

Word History and Origins

Origin of hydrogen¹

C18: from French hydrogène, from _hydro- + _-gen ; so called because its combustion produces water

Example Sentences

Shares of the hydrogen technology provider plunged 21% in after-hours trading to $1.71 after the company announced External link a capital raise.

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At that point President Truman ordered the development of the even more powerful hydrogen bomb.

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It has been deployed also by the military for mine detection, to search for lost submarines and, in one highly publicized case, to search for a hydrogen bomb lost at sea.

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Participants consumed water enriched with deuterium and oxygen-18, which are slightly heavier forms of hydrogen and oxygen.

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Authorities will also introduce a new financing program to support transportation companies that purchase electric and hydrogen buses.

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