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radiochemistry

(Encyclopedia)radiochemistry, chemistry of radioactive substances (see radioactivity). Radioactive isotopes are very useful as tracers to study the mechanisms of complex organic reactions, since even minute amounts...

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...

phonetics

(Encyclopedia)phonetics fōnĕtˈĭks, fə– [key], study of the sounds of languages from three basic points of view. Phonetics studies speech sounds according to their production in the vocal organs (articulatory...

soap

(Encyclopedia)soap, a cleansing agent. It cleanses by lowering the surface tension of water, by emulsifying grease, and by absorbing dirt into the foam. Ancient peoples are believed to have employed wood ashes and ...

steel

(Encyclopedia)steel, alloy of iron, carbon, and small proportions of other elements. Iron contains impurities in the form of silicon, phosphorus, sulfur, and manganese; steelmaking involves the removal of these imp...

color

(Encyclopedia)color, effect produced on the eye and its associated nerves by light waves of different wavelength or frequency. Light transmitted from an object to the eye stimulates the different color cones of the...

acids and bases

(Encyclopedia)acids and bases, two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Another theory that provides a very broad ...

topology

(Encyclopedia)CE5 Möbius strip: On the ordinary flat loop (A), an ant walking along the middle of the strip will pass only around the outside of the strip. If the strip is cut along the dotted line, twisted onc...

curve

(Encyclopedia)curve, in mathematics, a line no part of which is straight; more generally, it is considered to be any one-dimensional collection of points, thus including the straight line as a special kind of curve...

herbal

(Encyclopedia)herbal, early botanical book containing descriptions and illustrations of herbs and plants with their properties, chiefly those qualities that made them useful as medicines or condiments. Most of the ...