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thallium

(Encyclopedia)thallium thălˈēəm [key], metallic chemical element; symbol Tl; at. no. 81; interval in which at. wt. ranges 204.382–204.385; m.p. 303.5℃; b.p. about 1,457℃; sp. gr. 11.85 at 20℃; valence +...

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. ...

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...

Kopp, Hermann Franz Moritz

(Encyclopedia)Kopp, Hermann Franz Moritz hĕrˈmän fräntz mōˈrĭts kôp [key], 1817–92, German physical chemist and historian of chemistry. His research concerned the connection between the physical propertie...

Coblentz, William Weber

(Encyclopedia)Coblentz, William Weber kōˈblĕnts [key], 1873–1962, American physicist, b. North Lima, Ohio, grad. Case School of Applied Science (B.S., 1900) and Cornell (Ph.D., 1903). From 1905 to 1945 he was ...

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...

annealing

(Encyclopedia)annealing ənēlˈĭng [key], process in which glass, metals, and other materials are treated to render them less brittle and more workable. Annealing consists of heating the material and then cooling...

Wilson, Benjamin

(Encyclopedia)Wilson, Benjamin, 1721–88, English portrait painter and electrician who opposed Benjamin Franklin's theory of positive and negative electricity. Instead, Wilson supported Newton's gravitational-opti...

celluloid

(Encyclopedia)celluloid [from cellulose], transparent, colorless synthetic plastic made by treating cellulose nitrate with camphor and alcohol. Celluloid was the first important synthetic plastic and was widely use...

liquid crystal

(Encyclopedia)liquid crystal, liquid whose component particles, atoms or molecules, tend to arrange themselves with a degree of order far exceeding that found in ordinary liquids and approaching that of solid cryst...