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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...

sulfate

(Encyclopedia)sulfate, chemical compound containing the sulfate (SO4) radical. Sulfates are salts or esters of sulfuric acid, H2SO4, formed by replacing one or both of the hydrogens with a metal (e.g., sodium) or a...

balloon

(Encyclopedia)balloon, lighter-than-air craft without a propulsion system, lifted by inflation of one or more containers with a gas lighter than air or with heated air. During flight, altitude may be gained by disc...

Dhahran

(Encyclopedia)Dhahran däränˈ, däˌhəränˈ [key], city, NE Saudi Arabia, near the Persian Gulf...

Beck, Ludwig

(Encyclopedia)Beck, Ludwig lo͞otˈvĭkh bĕk [key], 1880–1944, German general, leader of resistance to Hitler. A highly cultivated career soldier, he served on the general staff during World War I and by 1933 ha...

bicarbonate

(Encyclopedia)bicarbonate or hydrogen carbonate, chemical compound containing the bicarbonate radical, –HCO3. The most familiar of such compounds is sodium bicarbonate (baking soda). See carbonate. ...

arc, in electricity

(Encyclopedia)arc, in electricity, highly luminous and intensely hot discharge of electricity between two electrodes. The arc was discovered early in the 19th cent. by the English scientist Sir Humphry Davy, who so...

Cavendish, Henry

(Encyclopedia)Cavendish, Henry, 1731–1810, English physicist and chemist, b. Nice. He was the son of Lord Charles Cavendish and grandson of the 2d duke of Devonshire. He was a recluse, and most of his writings we...

stellar evolution

(Encyclopedia)CE5 The above Hertzsprung-Russell (H-R) diagram shows the track of stellar evolution for a typical star. After spending much of its life evolving toward or along the main sequence, the star becomes...

salt, chemical compound

(Encyclopedia)salt, chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Salts are also prepared by methods other than neutralization. A metal can c...