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

The biggest cut was $1.2 billion for California’s ambitious project to develop clean hydrogen known as the Alliance for Renewable Clean Hydrogen Energy Systems, or ARCHES.

From Los Angeles Times

The organic waste separates into a flammable gas — made of carbon monoxide, carbon dioxide, methane and hydrogen — and a small amount of solid waste.

From Los Angeles Times

In the longer term, more radical solutions may become available, such as aircraft powered by hydrogen.

From BBC

But switching iron and steel-making plants over to green hydrogen hasn't gone as smoothly as some had expected.

From BBC

Toxic hydrogen sulfide escapes from nearby wells, giving the air the smell of “burnt rotten eggs,” Campos said.

From Salon