boron
boron (symbol B) Nonmetallic element of group III of the periodic table, first isolated in 1808 by English chemist Sir Humphry Davy. It occurs in several minerals, notably kernite (its chief ore) and borax. It has two allotropes: amorphous boron is an impure brown powder; metallic boron is a black to silver-grey hard crystalline material. It is used in semiconductor devices and the stable isotope B10 is a good neutron absorber, used in nuclear reactors and particle counters. Properties: at.no. 5; r.a.m. 10.81; r.d. 2.34 (cryst.), 2.37 (amorph.); m.p. 2079°C (3774°F); sublimes 2550°C (4622°F); most common isotope B11 (80.22%).
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boron
