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.
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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
hy·dro·gen (H),
(hī'drō-jen), 1. A gaseous element, atomic no. 1, atomic wt. 1.00794.
2. The molecular form (H
2) of the element. Synonym(s):
dihydrogen [hydro- + G. -gen, producing]
Farlex Partner Medical Dictionary © Farlex 2012
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, H
2.
Synonym(s):
dihydrogen.
[hydro- + G. -gen, producing]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
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.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
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]
Medical Dictionary for the Dental Professions © Farlex 2012