Columbia Encyclopedia

Search results

500 results found

palladium, chemical element

(Encyclopedia)palladium [Gr. Pallas, goddess of wisdom], metallic chemical element; symbol Pd; at. no. 46; at. wt. 106.42; m.p. 1,554℃; b.p. 2,970℃; sp. gr. 12.02 at 20℃; valence +2, +3, or +4. Palladium is a...

tracer

(Encyclopedia)tracer, an identifiable substance used to follow the course of a physical, chemical, or biological process. In chemistry the ideal tracer has the same chemical properties as the molecule it replaces a...

carboxyl group

(Encyclopedia)carboxyl group kärbŏkˈsĭl [key], in chemistry, functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond. Carboxylic a...

chemical bond

(Encyclopedia)chemical bond, mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the for...

fuel

(Encyclopedia)fuel, material that can be burned or otherwise consumed to produce heat. The common fuels used in industry, transportation, and the home are burned in air. The carbon and hydrogen in fuel rapidly comb...

battery, electric

(Encyclopedia)CE5 Lead storage cell: At the lead-dioxide electrode, electrons from the circuit combine with lead dioxide and sulfuric acid to form lead sulfate and water. At the spongy-lead electrode, lead react...

Codreanu, Corneliu Zelea

(Encyclopedia)Codreanu, Corneliu Zelea kŏrnĕˈlyo͞o zĕlˈyä kôdrĕäˈno͞o [key], 1899–1938, Romanian political leader and anti-Semitic terrorist. Active in the Romanian student movement against leftists a...

heat exhaustion

(Encyclopedia)heat exhaustion, condition caused by overexposure to sunlight or another heat source and resulting in dehydration and salt depletion, also known as heat prostration. The symptoms are severe headaches,...

Attica

(Encyclopedia)Attica ătˈĭkə [key], region of ancient Greece, a triangular area at the eastern end of central Greece, around Athens. According to Greek legend, the four Attic tribes were founded by Ion; in later...

MacKinnon, Roderick

(Encyclopedia)MacKinnon, Roderick, 1956–, American biochemist, b. Burlington, Mass., M.D. Tufts Univ., 1982. MacKinnon was on the faculty at Harvard Medical School from 1989–96 and has been a professor at the H...