INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site boron (B) A soft, brown, amorphous or hard crystalline nonmetallic element. Boron is the first element in group III of the periodic table, just above aluminum and next to carbon. Also described as a "metalloid" element, boron was first isolated by Humphrey Davy and, independently, by the French chemists Joseph-Louis Gay-Lussac and Louis-Jaques Thénard in 1808; it was identified as an element by Jons Jacob Berzelius in 1824. It is extracted chiefly from the ores borax and kernite. Its name comes from the Arabic buraq, for "borax". Boric acid is sometimes found in volcanic spring waters. Boron is used in pyrotechnics and flares to produce a green color. It has also been used in some rockets as an ignition source. Boron-10, one of two naturally occurring isotopes of boron (the other is boron-11), is a good absorber of neutrons and is therefore used in the control rods of nuclear reactors, as a radiation shield, and as a neutron detector (see boron counter). Boron filaments have found application in the aerospace industry because of their high strength and low weight. Boron is added to steels to make them hard. Pyrex glass is tough and heat resistant because of the boric oxide used to make it. atomic number 5 atomic mass 10.811 electron configuration 1s22s22p1 ionization energy first: 899 kJ/mol second: 2,422 kJ/mol third: 3,657 kJ/mol melting point 2300 °C (4172 °F) boiling point 2550 °C (4622 °F) density (at 20 °C) 2.34 g/cm3 Chemistry of boron Boron forms compounds directly with fluorine, chlorine, bromine, oxygen, sulfur, and carbon. Boron carbide, which is almost as hard as diamond, is formed when boron and carbon are heated together in an electric furnace. Although the properties of boron and most of its compounds are those of a non-metal, the element is unusual in that in boron phosphate it behaves like a metal. A great many uses have been found for the salts of boric acid – the borates. Borax – sodium borate – is a white soluble salt used in glass-making, soldering, the pottery industry, and in treating fabrics to make them fireproof. Boric acid, a white solid which can be made from borax, is used as a mild antiseptic, sometimes under the name of boracic acid. If borax is heated sufficiently it melts to form a glassy substance in which metallic oxides will dissolve. The compounds that are formed by the reaction between borax and the metal oxides are sometimes highly colored, the color being characteristic of the metal. Thus it is possible to identify the metal present by the color it gives to a borax bead. On account of the ability of metallic oxides to dissolve in molten borax, borax is used as a flux component in removing oxides from metal surfaces in preparation for soldering or welding. Borax is used in the manufacture of boro-silicate (Pyrex) glass which has good resistance to sudden temperature changes. The principal constituents of this type of glass (from which ovenware is made) are silica (about 80%) and borax (about 12%). Borax is also used in glazing pottery and other ceramic articles, in vitreous enamel finishes for stoves, cooker and baths, and for coating paper. Boron and life Boron is an essential trace element for the growth of plants, but is not required by animals – in fact, it can be toxic in excess. We take in about 2 milligrams of boron each day in our food. The possibility of boron-based life has been considered. Related category    • INORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP