A nonmetallic element that is amorphous and brown or crystalline and black, and is extracted chiefly from kernite and borax and used in flares, propellant mixtures, nuclear reactor control elements, abrasives, and hard metallic alloys. Atomic number 5; atomic weight 10.811; melting point 2,075°C; boiling point 4000°C; specific gravity (crystal) 2.34, (amorphous) 2.37; valence 3.
A shiny, brittle, black metalloid element extracted chiefly from borax. It is a good electrical conductor at high temperatures and a poor conductor at low temperatures. Boron is necessary for the growth of land plants and is used in the preparation of soaps, abrasives, and hard alloys. It is also used in the control rods of nuclear reactors as a neutron absorber. Atomic number 5; atomic weight 10.811; melting point 2,300°C; sublimation point 2,550°C; specific gravity (crystal) 2.34; valence 3.
(physics) A stable isotope, 105B, having five protons and five neutrons, that makes up about 20% of natural boron; it is a good absorber of slow neutrons and is used as a radiation shield in Geiger counters.
A nonmetallic chemical element occurring only in combination, as with sodium and oxygen in borax, and produced in the form of either a brown amorphous powder or very hard, brilliant crystals: its compounds are used in the preparation of boric acid, water softeners, soaps, enamels, glass, pottery, etc.: symbol, B; at. no. 5
(physics) A stable isotope, 115B, having five protons and six neutrons, that makes up about 80% of natural boron.
Other Word Forms
Origin of boron
American Heritage Dictionary of the English Language, 5th Edition
From stem of borax + -on (“ending used to form names of substances”)
Boron Sentence Examples
Conspicuous examples are afforded by oxygen, carbon, boron, silicon, phosphorus, mercuric oxide and iodide.
Thenard in 1808 by heating boron trioxide with potassium, in an iron tube.
After the vigorous reaction has ceased and all the sodium has been used up, the mass is thrown into dilute hydrochloric acid, when the soluble sodium salts go into solution, and the insoluble boron remains as a brown powder, which may by filtered off and dried.
This mixture burns with a green flame forming boron trioxide; whilst boron is deposited on passing the gas mixture through a hot tube, or on depressing a cold surface in the gas flame.
In 1927 a very large deposit of relatively pure Borax was discovered at what is now Boron, CA, in the Mojave Desert.