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boron    音标拼音: [b'ɔr,ɑn]
n. 硼

硼

boron
n 1: a trivalent metalloid element; occurs both in a hard black
crystal and in the form of a yellow or brown powder [synonym:
{boron}, {B}, {atomic number 5}]

Boron \Bo"ron\ (b[=o]"r[o^]n), n. [See {Borax}.] (Chem.)
A nonmetallic element occurring abundantly in borax. It is
reduced with difficulty to the free state, when it can be
obtained in several different forms; viz., as a substance of
a deep olive color, in a semimetallic form, and in colorless
quadratic crystals similar to the diamond in hardness and
other properties. It occurs in nature also in boracite,
datolite, tourmaline, and some other minerals. Atomic number
5. Atomic weight 10.81. Symbol B.
[1913 Webster]

boron
Symbol: B
Atomic number: 5
Atomic weight: 10.811
An element of group 13 of the periodic table. There are two allotropes,
amorphous boron is a brown power, but metallic boron is black. The
metallic form is hard (9.3 on Mohs' scale) and a bad conductor in room
temperatures. It is never found free in nature. Boron-10 is used in
nuclear reactor control rods and shields. It was discovered in 1808 by
Sir
Humphry Davy and by J.L. Gay-Lussac and L.J. Thenard.


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