Relative atomic mass: 10.811 +- 0.007

English: Boron
French: Bore
Croatian: Bor
German: Bor
Italian: Boro
Spanish: Boro

Atomic number: 5
Group numbers: 13
Period: 2
Standard state (20 oC): solid

Discovery: 1808 Sir Humphry Davy (GB); Joseph-Louis Gay-Lussac, Louis-Jaques Thenard (FR)
Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy (GB) and independently by Joseph-Louis Gay-Lussac and Louis-Jaques Thenard (FR). The origin of the name comes from the Arabic word buraq and the Persian word burah meaning boraks (Na2B4O7*10H2O). It is hard, brittle, lustrous black semimetal. Boron is unreactive with oxygen, water, alkalis or acids. It combines with most metals to form borides. Boron is obtained from kernite, a kind of borax (Na2B4O7.10H2O). High purity boron is produced by electrolysis of molten potassium fluroborate and potassium chloride (KCl). Amorphous boron is used in pyrotechnic flares to provide a distinctive green colour and in rockets as an igniter. The price of 99.5 % pure boron pieces is 997.90 for 250 g.
Electronic configuration: [He] 2s2 2p1
Formal oxidation number: +3
Atomic radius: 79.5 pm

Electronegativities: 2.04
Thermal conductivity: 27 W/(m K)
Electrical resistivity (20 oC): 1.8E+12 microOhm cm

Melting point: 2075 oC
Boiling point: 4000 oC

Heat of fusion: 22.2 kJ/mol
Heat of vaporization: 504.5 kJ/mol
Heat of atomization: 557.64 kJ/mol

4Be <= 5B => 6C

ASCII Periodic Table of the Elements
29 Aug. 2017
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