Columbia Encyclopedia

Search results

361 results found

alcohol

(Encyclopedia)CE5 Alcohols alcohol, any of a class of organic compounds with the general formula R–OH, where R represents an alkyl group made up of carbon and hydrogen in various proportions and –OH represe...

lava

(Encyclopedia)lava läˈvə [key], molten rock that erupts on the earth's surface, either on land or under the ocean, by a volcano or through a fissure. It solidifies into igneous rock that is also called lava. Bef...

statistical mechanics

(Encyclopedia)statistical mechanics, quantitative study of systems consisting of a large number of interacting elements, such as the atoms or molecules of a solid, liquid, or gas, or the individual quanta of light ...

diode

(Encyclopedia)diode dīˈōd [key], two-terminal electronic device that permits current flow predominantly in only one direction. Most diodes are semiconductor devices; diode electron tubes are now used only for a ...

charcoal

(Encyclopedia)charcoal, substance obtained by partial burning or carbonization (destructive distillation) of organic material. It is largely pure carbon. The entry of air during the carbonization process is control...

iodine

(Encyclopedia)iodine īˈədīn, –dĭn [key] [Gr.,=violet], nonmetallic chemical element; symbol I; at. no. 53; at. wt. 126.90447; m.p. 113.5℃; b.p. 184.35℃; sp. gr. 4.93 at 20℃; valence −1, +1, +3, +5, o...

halogen

(Encyclopedia)halogen hălˈəjĕn [key] [Gr.,=salt-bearing], any of the chemically active elements found in Group 17 of the periodic table; the name applies especially to fluorine (symbol F), chlorine (Cl), bromin...

mercury poisoning

(Encyclopedia)mercury poisoning, tissue damage resulting from exposure to more than trace amounts of the element mercury or its compounds. Elemental mercury (the silver liquid familiar from thermometers) is the mos...

particle detector

(Encyclopedia)CE5 Particle detector—Bubble chamber: A. Pressure drops as piston is raised; B. Charged particles passing through chamber ionize atoms in liquid; C. Bubbles form around atoms and form visible tra...

superconductivity

(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...