hydrogen


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hydrogen

 (H) [hi´dro-jen]
a chemical element, atomic number 1, atomic weight 1.00797. (See Appendix 6.) It exists as the mass 1 isotope (protium, or light or ordinary hydrogen), mass 2 isotope (deuterium, heavy hydrogen), and mass 3 isotope (tritium).
hydrogen cyanide an extremely poisonous colorless liquid or gas, HCN, a decomposition product of various naturally occurring glycosides and a common cause of cyanide poisoning. Inhalation of the gas can cause death within a minute. Called also hydrocyanic acid.
heavy hydrogen deuterium.
hydrogen ion concentration the degree of concentration of hydrogen ions (the acid element) in a solution. Its symbol is pH, and it expresses the degree to which a solution is acidic or alkaline. The pH range extends from 0 to 14, pH 7 being neutral, a pH of less than 7 indicating acidity, and one above 7 indicating alkalinity. See also acid-base balance.
hydrogen peroxide H2O2, an antiseptic with a mildly antibacterial action. A 3 per cent solution foams on touching skin or mucous membrane and appears to have a mechanical cleansing action.
hydrogen sulfide H2S, a poisonous gas with an offensive smell, released from decaying organic material, natural gas, petroleum, and sulfur deposits, and sometimes used as a chemical reagent.

hy·dro·gen (H),

(hī'drō-jen),
1. A gaseous element, atomic no. 1, atomic wt. 1.00794.
2. The molecular form (H2) of the element. Synonym(s): dihydrogen
[hydro- + G. -gen, producing]

hydrogen

/hy·dro·gen/ (H) (hi´dro-jen) chemical element, at. no. 1; it exists as the mass 1 isotope (protium, light or ordinary h.), mass 2 isotope (deuterium, heavy h.), and mass 3 isotope (tritium) .
hydrogen cyanide  an extremely poisonous liquid or gas, HCN, used as a rodenticide and insecticide.
hydrogen peroxide  a strongly disinfectant cleansing and bleaching liquid, H2O2, used in dilute solution in water.
hydrogen sulfide  an ill-smelling, colorless, poisonous gas, H2S.

hydrogen (H)

[hī′drəjən]
Etymology: Gk, hydor + genein, to produce
a gaseous monovalent element. Its atomic number is 1; its atomic mass is 1.008. It is the simplest and the lightest of the elements and is a colorless, odorless, highly flammable diatomic gas. It occurs in pure form only sparsely in the earth and the atmosphere but is plentiful in the sun and in many other stars. Hydrogen is a component of numerous compounds, many of them produced by the body. As a component of water, hydrogen is crucial in the metabolic interaction of acids, bases, and salts within the body and in the fluid balance necessary for the body to survive.

hy·dro·gen

(H) (hī'drō-jen)
1. A gaseous element, atomic no. 1, atomic wt. 1.00794.
2. The molecular form of the element, H2.
Synonym(s): dihydrogen.
[hydro- + G. -gen, producing]

Hydrogen

The simplest, most common element known in the universe. It is composed of a single electron (negatively charged particle) circling a nucleus consisting of a single proton (positively charged particle). It is the nuclear proton of hydrogen that makes MRI possible by reacting resonantly to radio waves while aligned in a magnetic field.

hy·dro·gen

(hī'drō-jen)
1. Gaseous element, atomic no. 1, atomic wt. 1.00794.
2. Molecular form (H2) of the element.
[hydro- + G. -gen, producing]

hydrogen (H),

n a gaseous, univalent element. Its atomic number is 1 and its atomic weight is 1.008. It is the simplest and lightest of the elements and is normally a colorless, odorless, highly flammable diatonic gas.
hydrogen peroxide,
n an unstable compound of hydrogen and oxygen that is easily broken down into water and oxygen. A 3% solution is used as a mild antiseptic for the skin and mucous membranes; more concentrated solutions may be used as a whitening (bleaching) agent. May be used to reduce gingival inflammation, but may not eliminate the responsible bacteria.

hydrogen

a chemical element, atomic number 1, atomic weight 1.00797, symbol H. See Table 6. It exists as the mass 1 isotope (protium, or light or ordinary hydrogen), mass 2 isotope (deuterium, heavy hydrogen), and mass 3 isotope (tritium).

hydrogen bonding
weak electrostatic attraction between one electronegative atom and the hydrogen atom covalently linked to a second electronegative atom.
hydrogen breath test
detects hydrogen production as a product of bacterial fermentation of carbohydrates, an indicator of inflammatory bowel disease or carbohydrate malabsorption.
hydrogen cyanide
hydrocyanic acid.
heavy hydrogen
hydrogen having double the mass of ordinary hydrogen; deuterium.
hydrogen ion balance
hydrogen ion concentration
the degree of concentration of hydrogen ions (the acid element) in a solution. Its symbol is pH, and expresses the degree to which a solution is acidic or alkaline. The pH range extends from 0 to 14, pH 7 being neutral. A pH of less than 7 indicates acidity, above 7 indicates alkalinity. See also acid-base balance and ph.
hydrogen peroxide
H2O2, used in solution as an antibacterial agent. A 3% solution foams on touching skin or mucous membrane and appears to have a mechanical cleansing action.
hydrogen peroxide-based teat dips
hydrogen sulfide
an ill-smelling, colorless, poisonous gas, H2S; much used as a chemical reagent. Hydrogen sulfide is often present in gases from oil wells and from manure vats under slatted floor barns. Poisoning of cattle causes diarrhea, dehydration, dyspnea and death in convulsions. The feces are black and the breath smells of hydrogen sulfide. Called also hydrosulfuric acid. See also manure pit gas poisoning.
hydrogen swell
defective canned meat can. Can is distended due to production of hydrogen as a result of corrosion of the can surface.
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Among its achievements is a manual for first responders to the scene of FCV accidents that addresses how to deal with hydrogen tanks in wrecked vehicles.
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The roadmap describes routes to production, delivery, storage, conversion to useful power, and applications for hydrogen fuel.
The hydrogen uses very little gasoline, but allows a lean mixture to be used by making the engine more tolerant of lean-burn conditions," says Botti.
But equally important motivations for exploring hydrogen are the energy-related problems of energy security, air pollution, and climate change--problems that are collectively calling into question the fundamental sustainability of the current energy system.
Tests with gas streams that contained water and hydrogen sulfide indicated that the membrane was also more permeable to those contaminants than to hydrogen, says Freeman.
In recent years, GM has been one of the auto industry's most vocal champions of hydrogen fuel cells, which generate electricity from a chemical reaction between hydrogen and oxygen and release only water as waste.
Although using steam to reform natural gas has proven thus far to be the cheapest way to produce commercial hydrogen, global production of natural gas is likely to peak sometime between 2020 and 2030, creating a second energy crisis on the heels of the oil crisis.
The solubility of hydrogen in molten aluminum increases with temperature (Fig.