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element

(Encyclopedia)CE5 element, in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means o...

Barton, Derek H. R.

(Encyclopedia)Barton, Derek H. R., 1918–98, British chemist, b. Gravesend, England, grad. Imperial College of Science and Technology (B.S. 1940, Ph.D. 1942, D.Sc. 1949). He was on the faculty of Imperial College ...

nitrate

(Encyclopedia)nitrate, chemical compound containing the nitrate (NO3) radical. Nitrates are salts or esters of nitric acid, HNO3, formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radic...

ammonium group

(Encyclopedia)ammonium group, in chemistry, a positively charged nitrogen atom joined by single bonds to four other atoms or groups. The simplest ammonium group, NH4+, is formed by protonation of ammonia, NH3, e.g....

Organization for the Prohibition of Chemical Weapons

(Encyclopedia)Organization for the Prohibition of Chemical Weapons (OPCW), international body (est. 1997) responsible for the implementation of the Chemical Weapons Convention (CWC), which aims at the destruction o...

hydrazine

(Encyclopedia)hydrazine hīˈdrəzēnˌ [key], chemical compound, formula NH2NH2, m.p. 1.4℃, b.p. 113.5℃, specific gravity 1.011 at 15℃. It is very soluble in water and soluble in alcohol. At ordinary tempera...

Fermi, Enrico

(Encyclopedia)Fermi, Enrico ĕnrēˈkō fĕrˈmē [key], 1901–54, American physicist, b. Italy. He studied at Pisa, Göttingen, and Leiden, and taught physics at the universities of Florence and Rome. He contribu...

anaphylaxis

(Encyclopedia)anaphylaxis ănˌəfəlăkˈsĭs [key], hypersensitive state that may develop after introduction of a foreign protein or other antigen into the body tissues. When an anaphylactic state exists, a secon...

histology

(Encyclopedia)histology hĭstŏlˈəjē [key], study of the groups of specialized cells called tissues that are found in most multicellular plants and animals. Histologists study the organization of tissues at all ...

combustion

(Encyclopedia)combustion, rapid chemical reaction of two or more substances with a characteristic liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g., wood, coal, oil, or natura...