Chemistry of Boron (Z=5)

The name Boron comes from the Arabic and Persian words for borax, its principal ore. Although compounds of boron were known in ancient times, it was first isolated in 1808 by Gay-Lussac and Thénard and independently by Sir Humphry Davy (who has a lot of elements to his credit!).

Boron exists in the earth's crust to the extent of only about 10 ppm (about the same abundance as lead). The pure element is shiny and black. It is very hard and in extremely pure form is nearly as hard as diamond, but much too brittle for practical use. At high temperatures it is a good conductor but at room temperature and below is an insulator. This behavior as well as many of its other properties earn it the classification of a metalloid. In addition to the crystalline form of boron there is also an amorphous dark brown powder (as shown above).

The element can be prepared by the reduction of borax (Na₂B₄O₇) with carbon. High-purity boron can be produced by electrolysis of molten potassium fluoroborate. Common compounds of boron include borax and boric acid (H₃BO₃).