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alkaline-earth metals

(Encyclopedia)alkaline-earth metals, metals constituting Group 2 of the periodic table. Generally, they are softer than most other metals, react readily with water (especially when heated), and are powerful reducin...

francium

(Encyclopedia)francium frănˈsēəm [key] [from France], radioactive chemical element; symbol Fr; at. no. 87; mass no. of most stable isotope 223; m.p. about 27℃ (estimated); b.p. 677℃ (estimated); sp. gr. unk...

Hot Springs

(Encyclopedia)Hot Springs. <1> City (2020 pop. 37,930), seat of Garland co., W central Ark.; settled 1807, inc. 1876. The city nearly surrounds Hot Springs Nati...

string theory

(Encyclopedia)string theory, description of elementary particles based on one-dimensional curves, or “strings,” instead of point particles. Superstring theory, which is string theory that contains a kind of sym...

helium

(Encyclopedia)helium hēˈlēəm [key], gaseous chemical element; symbol He; at. no. 2; at. wt. 4.0026; m.p. below −272℃ at 26 atmospheres pressure; b.p. −268.934℃ at 1 atmosphere pressure; density 0.1785 g...

silicon

(Encyclopedia)silicon, nonmetallic chemical element; symbol Si; at. no. 14; interval in which at. wt. ranges 28.084–28.086; m.p. 1,410℃; b.p. 2,355℃; sp. gr. 2.33 at 25℃; valence usually +4. Silicon is the ...

nitrous oxide

(Encyclopedia)nitrous oxide or nitrogen (I) oxide, chemical compound, N2O, a colorless gas with a sweetish taste and odor. Its density is 1.977 grams per liter at STP. It is soluble in water, alcohol, ether, and ot...

Autry, Gene

(Encyclopedia)Autry, Gene (Orvon Grover Autry), 1907–98, American entertainer and businessman, b. Tioga Springs, Tex. Probably the most successful of the movies' singing cowboys, Autry began singing o...

object-oriented programming

(Encyclopedia)object-oriented programming, a modular approach to computer program (software) design. Each module, or object, combines data and procedures (sequences of instructions) that act on the data; in traditi...

medicinal plants

(Encyclopedia)medicinal plants, plants used as natural medicines. This practice has existed since prehistoric times. There are three ways in which plants have been found useful in medicine. First, they may be used ...