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Boron

Metalloidsolid
Symbol: B
Atomic number: 5
Atomic mass: 10.811
Group: Non-Metal
CAS-number: 7440-42-8

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Physical data
Isotopes
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 3
Orbitals: [He] 2s2 2p1
Electronegativity: 2.0, 2.0
1. Ionization potential: 8.2980 eV
2. Ionization potential: 25.154 eV
3. Ionization potential: 37.93 eV
Oxidation states: 3
Electrical conductivity: 1.0e-12 10^6
Melting point: 2079 °C
Boiling point: 4000 °C
Specific heat: 1.02 J/gK
Heat of fusion: 50.20 kJ/mol
Heat of vaporization: 489.70 kJ/mol
Thermal conductivity: 0.270 W/cmK
Atomic radius: 1.17 Å
Ionic radius: 0.23 Å (+3)
Covalent radius: 0.82 Å
Atomic volume: 4.6 cm³/mol
Density (293 K): 2.34 g/cm³
Crystal structure: rhombohedral
rhombohedral

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
10B 19.7 10.0129 3 -- --
11B 80.3 11.0093 3/2 -- --

Other info

Name origin:From Arabic and Persian words for borax
Description:Hard, brittle, lustrous black semimetal. Exists in the earth's crust at an average proportion of about 10 parts per million (ppm).
Discovered by:Sir H. Davy, J.L. Gay-Lussac, L.J. Thénard
Year:1808
Place:England/France
Sources:Obtained from kernite, a kind of borax (Na2B4O7.10H2O). High purity boron is produced by electrolysis of molten potassium fluroborate and potassium chloride (KCl).
Use(s):Used with titanium & tungsten to make heat resistant alloys for jets & rockets.