Template:Infobox boron

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5 beryllium ← boron → carbon - ↑ B ↓ Al Periodic table - Extended periodic table
General
Name, symbol, number	boron, B, 5
Chemical series	metalloids
Group, period, block	13, 2, p
Appearance	black/brown
Standard atomic weight	10.811(7) g·mol−1
Electron configuration	1s2 2s2 2p1
Electrons per shell	2, 3
Physical properties
Phase	solid
Density (near r.t.)	2.34 g·cm−3
Liquid density at m.p.	2.08 g·cm−3
Melting point	2349 K (2076 °C, 3769 °F)
Boiling point	4200 K (3927 °C, 7101 °F)
Heat of fusion	50.2 kJ·mol−1
Heat of vaporization	480 kJ·mol−1
Specific heat capacity	(25 °C) 11.087 J·mol−1·K−1
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 2348 2562 2822 3141 3545 4072
Atomic properties
Crystal structure	rhombohedral
Oxidation states	4,[1] 3, 1[2] (mildly acidic oxide)
Electronegativity	2.04 (Pauling scale)
Ionization energies (more)	1st: 800.6 kJ·mol−1
	2nd: 2427.1 kJ·mol−1
	3rd: 3659.7 kJ·mol−1
Atomic radius	85 pm
Atomic radius (calc.)	87 pm
Covalent radius	82 pm
Miscellaneous
Magnetic ordering	nonmagnetic
Electrical resistivity	(20 °C) 1.5×104Ω·m
Thermal conductivity	(300 K) 27.4 W·m−1·K−1
Thermal expansion	(25 °C) 5–7 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 16200 m/s
Bulk modulus	(β form) 185 GPa
Mohs hardness	9.3
Vickers hardness	49000 MPa
CAS registry number	7440-42-8
Selected isotopes
Main article: Isotopes of boron iso NA half-life DM DE (MeV) DP 10B 18.8%* 10B is stable with 5 neutrons 11B 81.2%* 11B is stable with 6 neutrons *Boron-10 content may be as low as 19.1% and as high as 20.3% in natural samples. Boron-11 is the remainder in such cases.
References
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