Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Beryllium

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Beryllium, symbol Be, gray, brittle metallic element, with an atomic number of 4. It is in group 2 (or IIa) of the periodic table (see Periodic Law). Beryllium was named for its chief mineral, beryl, an aluminum beryllium silicate. It was discovered as an oxide, now known as beryllia, in 1797 by French chemist Louis Nicolas Vauquelin. The free element was first isolated in 1828 independently by Friedrich Wöhler and Antonine Alexandre Brutus Bussy. Because the soluble compounds are sweet-tasting, the new element was first called glucinium, a reference to the sugar glucose.

PROPERTIES AND OCCURRENCE

Beryllium, one of the alkaline earth metals, ranks about 51st in natural abundance among the elements in the earth's crust. Its atomic weight is 9.012. Beryllium melts at about 1287° C (about 2349° F), boils at about 3000° C (about 5432° F), and has a specific gravity of 1.85. Beryllium has a high strength per unit weight. It tarnishes only slightly in air, becoming covered with a thin layer of oxide. The ability of beryllium to scratch glass is usually ascribed to this oxide coating. Beryllium compounds are generally white (or colorless in solution) and show great similarity in chemical properties to the corresponding compounds of aluminum. This similarity makes it difficult to separate beryllium from the aluminum that is almost always present in beryllium ores.

USES

The addition of beryllium to some alloys often results in products that have high heat resistance, improved corrosion resistance, greater hardness, greater insulating properties, and better casting qualities. Many parts of supersonic aircraft are made of beryllium alloys because of their lightness, stiffness, and dimensional stability. Other applications make use of the nonmagnetic and nonsparking qualities of beryllium and the ability of the metal to conduct electricity. Beryllium has important use in so-called multiplexing systems. In miniature, high-purity components made with beryllium, a single wire can carry hundreds of electronic signals.

Because X rays easily pass through pure beryllium, the element is used as window material for X-ray tubes. Beryllium and its oxide, beryllia, are also used as a moderator, or so-called blanket, around the core of a nuclear reactor because of the tendency of beryllium to slow down or capture neutrons (see Nuclear Energy).