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uranium

(Encyclopedia)uranium yo͞orāˈnēəm [key], radioactive metallic chemical element; symbol U; at. no. 92; mass number of most stable isotope 238; m.p. 1,132℃; b.p. 3,818℃; sp. gr. 19.1 at 25℃; valence +3, +4...

ethanol

(Encyclopedia)ethanol ĕthˈənōlˌ [key] or ethyl alcohol, CH3CH2OH, a colorless liquid with characteristic odor and taste; commonly called grain alcohol or simply alcohol. Ethanol is used extensively as a solv...

protozoan

(Encyclopedia)protozoan prōˌtəzōˈən [key], informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms ...

epoxy group

(Encyclopedia)epoxy group ĕpˈŏksē [key], in chemistry, functional group that consists of an oxygen atom joined by single bonds to two adjacent carbon atoms, thus forming the three-membered epoxide ring. It is t...

allotropy

(Encyclopedia)allotropy əlŏˈtrəpē [key] [Gr.,=other form]. A chemical element is said to exhibit allotropy when it occurs in two or more forms in the same physical state; the forms are called allotropes. Allot...

Huaynaputina

(Encyclopedia)Huaynaputina, volcano, 15,912 ft (4,850 m) high, Moquegua region, S Peru, in the central Andes. A stratovolcano, it lies on the W rim of the Río Tambo canyon and has several ash cones within its crat...

Ostwald, Wilhelm

(Encyclopedia)Ostwald, Wilhelm vĭlˈhĕlm ôstˈvält [key], 1853–1932, German physical chemist and natural philosopher, b. Riga, Latvia. He was professor of chemistry and director of the chemical laboratory (18...

stereochemistry

(Encyclopedia)stereochemistry, study of the three-dimensional configuration of the atoms that make up a molecule and the ways in which this arrangement affects the physical and chemical properties of the molecule. ...

Bessemer process

(Encyclopedia)CE5 Bessemer converter Bessemer process bĕsˈəmər [key] [for Sir Henry Bessemer], industrial process for the manufacture of steel from molten pig iron. The principle involved is that of oxidati...

cyclic compound

(Encyclopedia)cyclic compound, any one of a class of compounds whose molecules contain a number of atoms bonded together to form a closed chain or ring. If all of the atoms that form the ring are carbon, the compou...