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]

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]
References in periodicals archive ?
okinawensi uses carbon dioxide as a carbon source and molecular hydrogen for energy, as a suspected Enceladus microbe might.
Caption: Figure 3: Mass spectrometric data on temperature dependences of atomic and molecular hydrogen desorption from the nc-SiC films of the A (a), B (b), and C (c) types and integral hydrogen desorption from nc-SiC A, B, and C films versus temperature (d).
Molecular hydrogen attenuates hypoxia/reoxygenation injury of intrahepatic cholangiocytes by activating Nrf2 expression.
Ohta, "Recent progress toward hydrogen medicine: potential of molecular hydrogen for preventive and therapeutic applications," Current Pharmaceutical Design, vol.
The aforementioned reactions depend on the presence of molecular hydrogen in the chromosphere.
For example, molecular hydrogen exists in low concentrations and must be extracted from natural gas or water, which are typically slow, energy-intensive processes.
They produce methane using the molecular hydrogen generated by other microbes during rumen fermentation as a source of energy.
Miyamoto; Ab Initio Investigation of Physisorption of Molecular Hydrogen on Planar y Curved Graphenes, J.
* Hydrolysis: by the activity of extracellular enzymes, macromolecular materials are outside the cell split into simpler organic substances, first of all fatty acids, alcohols, carbon dioxide (CO2) and molecular hydrogen (H2).
In the case of steel, hydrogen damage may reveal itself as delayed hydrogen cracking, degradation of mechanical properties, especially ductility, and can change microstructures and create bubbles filled with molecular hydrogen, methane or hydrogen sulfide.
(5) On reaching levels of decreased pressure in the upper mantle and lower crust, ionic hydrogen would escape as molecular hydrogen and molecular gases, silane (Si[H.sub.4]) and methane (C[H.sub.4]) in particular.
Molecular hydrogen dissolves into the metal alloy phase and then travels through the membrane, where it exits and forms molecular hydrogen once again.

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