See Also: hydrogen ion(medicine)
hydrogen-1(medicine)
hydrogen-2(medicine)
hydrogen-3(medicine)
hydrogen(dictionary)
hydrogen(dictionary)
Hydrogen(medicine)
hydrogen(encyclopedia)
hydrogen number(medicine)
hydrogen peroxide(medicine)

Cheviot (iou) and hydrogen (sh)


Cheviot (iou)



Cheviot noun. In sense 2 also cheviot. L18.
[from Cheviot Hills on the England-Scotland border.]
In full Cheviot sheep. (An animal of) a breed of sheep from the Cheviot Hills. L18.
(Cloth made from) the wool of Cheviot sheep. M19.

hydrogen (sh)




Lightest chemical element, chemical symbol H, atomic number 1.

A colourless, odourless, tasteless, flammable gas, it occurs as the diatomic molecule H2. Its atom consists of one proton (the nucleus) and one electron; the isotopes deuterium and tritium have an additional one and two nuclear neutrons, respectively. Though only the ninth most abundant element on Earth, it represents about 75% of all matter in the universe. Hydrogen was formerly used to fill airships; nonflammable helium has replaced it. It is used to synthesize ammonia, ethanol, aniline, and methanol; to treat petroleum fuels; as a reducing agent (see reduction) and to supply a reducing atmosphere; to make hydrogen chloride (see hydrochloric acid) and hydrogen bromide; and in hydrogenation (e.g., of fats). Liquid hydrogen (boiling point -423 ¡ãF [-252.8 ¡ãC]) is used in scientific and commercial applications to produce extremely low temperatures and as a rocket propellant and a fuel for fuel cells. Combustion of hydrogen with oxygen gives water as the sole product. The properties of most acids, especially in water solutions, arise from the hydrogen ion (H+, also referred to as the hydronium ion, H3O+, the form in which H+ is found in a water environment). See also hydride; hydrocarbon.