Definition of Hydrogen

1. Noun. A nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe.

Exact synonyms: Atomic Number 1, H
Specialized synonyms: Tritium
Generic synonyms: Chemical Element, Element, Gas
Substance meronyms: H2o, Water
Derivative terms: Hydrogenate

Definition of Hydrogen

1. n. A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.

Definition of Hydrogen

1. Noun. The lightest chemical element (''symbol'' H) with an atomic number of 1 and atomic weight of 1.00794. ¹

2. Noun. Molecular hydrogen (H2), a colourless, odourless and flammable gas at room temperature. ¹

3. Noun. An atom of the element. ¹

4. Noun. A sample of the element. ¹

¹ Source:

Definition of Hydrogen

1. a gaseous element [n -S]

Medical Definition of Hydrogen

1. Hydrogen is a gas element which has an atomic number of 1 and an atomic weight of 1.0079. It combines with oxygen to form water (H20) and is present in all organic compounds. A few types of bacteria can metabolise atmospheric hydrogen (H2). Hydrogen gas itself is not poisonous, but when it mixes with air it can easily ignite or explode. Hydrogen was discovered by Henry Cavendish in 1766 and was named by Lavoisier. There are two main isotopes of hydrogen: deuterium (2H) and tritium (3H, which is radioactive and is used in some glow-in-the-dark paints and as a tracer in biological studies). Abbreviation: H (09 Oct 1997)

Hydrogen Pictures

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Lexicographical Neighbors of Hydrogen

hydrofoil craft
hydrogen (current term)
hydrogen-potassium-exchanging atpase
hydrogen-transporting ATP synthase
hydrogen acceptor
hydrogen acetate
hydrogen acid
hydrogen air
hydrogen arsenide

Literary usage of Hydrogen

Below you will find example usage of this term as found in modern and/or classical literature:

1. Proceedings of the Royal Society of London by Royal Society (Great Britain) (1888)
"On the Classification [Apr., stars, the outer constituent of the atmosphere—hydrogen—alone being raised by the friction to brilliant incandescence. ..."

2. Journal of the American Chemical Society by American Chemical Society (1898)
"THE addition of a large excess of hydrogen peroxide to a solution of a ferric salt does not prevent the precipitation of ferric hydroxide on addition of ..."

3. The Philosophical Magazine (1830)
"... of hydrogen are known ; one is solid, and is composed of Arsenic 97416 hydrogen 2'584 100- These proportions are considered by M. ..."

4. The American Year Book: A Record of Events and Progress by Francis Graham Wickware, (, Albert Bushnell Hart, (, Simon Newton Dexter North (1916)
"hydrogen Peroxide.—The behavior of hydrogen peroxide toward various salts has been ... Treatment of cesium carbonate with 30 per cent, hydrogen peroxide, ..."

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