Template:Infobox boron

Boron, ₅B
	Template:Infobox element/symbol-to-top-image-caption
General properties
Pronunciation	Template:Infobox element/pronunciation
Allotropes	α-, β-rhombohedral, β-tetragonal (and more)
Appearance	black-brown
Standard atomic weight (Ar, standard)	Template:Infobox element/standard atomic weight
Mass number	Template:Infobox element/symbol-to-most-stable-isotope (most stable isotope)
Boron in the periodic table
	Template:Infobox element/periodic table
Atomic number (Z)	5
Group	Template:Infobox element/group
Period	period 2
Block	p-block
Element category	Template:Infobox element/category format
Electron configuration	[He] 2s2 2p1
Electrons per shell	2, 3
Physical properties
Phase at STP	solid
Melting point	2349 K (2076 °C, 3769 °F)
Boiling point	4200 K (3927 °C, 7101 °F)
Density when liquid (at m.p.)	2.08 g/cm3
Heat of fusion	50.2 kJ/mol
[[Enthalpy of vaporization\|Heat of Template:Engvar]]	508 kJ/mol
Molar heat capacity	11.087 J/(mol·K)
	[[Vapor pressure\|Template:Engvar pressure]] Template:Infobox element/vapor pressure table
Atomic properties
Oxidation states	Template:Infobox element/symbol-to-oxidation-state
Electronegativity	Pauling scale: 2.04
[[Ionization energy\|Template:Engvar energies]]	1st: 800.6 kJ/mol ; 2nd: 2427.1 kJ/mol ; 3rd: 3659.7 kJ/mol ; (more) ;
Atomic radius	empirical: 90 pm
Covalent radius	84±3 pm
Van der Waals radius	192 pm
	Template:Infobox element/spectral lines
Other properties
Crystal structure	Template:Infobox element/crystal structure Template:Infobox element/crystal structure
Speed of sound thin rod	16,200 m/s (at 20 °C)
Thermal expansion	β form: 5–7 µm/(m·K) (at 25 °C)
Thermal conductivity	27.4 W/(m·K)
Electrical resistivity	~106 Ω·m (at 20 °C)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−6.7·10−6 cm3/mol
Mohs hardness	~9.5
CAS Number	7440-42-8
History
Discovery	Joseph Louis Gay-Lussac and Louis Jacques Thénard (30 June 1808)
First isolation	Humphry Davy (9 July 1808)
Main isotopes of boron
	Template:Infobox element/isotopes table
	10B content may be as low as 19.1% and as high as 20.3% in natural samples. 11B is the remainder in such cases.
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Template:Infobox element/element navigation Template:Template reference list Five of these are named references. They may be cited in the containing article as

<ref name="v1" /> for the source Infrared Emission Spectroscopy of BF and AIF
<ref name="magnet" /> for the source from Handbook of Chemistry and Physics
<ref name="NISTic" /> for the source Atomic Weights and Isotopic Compositions for All Elements
<ref name="Lussac" /> for the source by Gay-Lussac
<ref name="Davy" /> for the source by Davy

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↑ Holcombe Jr., C. E.; Smith, D. D.; Lorc, J. D.; Duerlesen, W. K.; Carpenter; D. A. (October 1973). "Physical-Chemical Properties of beta-Rhombohedral Boron". High Temp. Sci. 5 (5): 349–57.
↑ Lide, David R. (ed.) (2000). Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics (PDF). CRC press. ISBN 0849304814.CS1 maint: Extra text: authors list (link)
↑ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
↑ Gay Lussac, J.L. & Thenard, L.J. (1808). "Sur la décomposition et la recomposition de l'acide boracique". Annales de chimie. 68: 169–174.
↑ Davy H (1809). "An account of some new analytical researches on the nature of certain bodies, particularly the alkalies, phosphorus, sulphur, carbonaceous matter, and the acids hitherto undecomposed: with some general observations on chemical theory". Philosophical Transactions of the Royal Society of London. 99: 39–104. doi:10.1098/rstl.1809.0005.
↑ Szegedi, S.; Váradi, M.; Buczkó, Cs. M.; Várnagy, M.; Sztaricskai, T. (1990). "Determination of boron in glass by neutron transmission method". Journal of Radioanalytical and Nuclear Chemistry Letters. 146 (3): 177. doi:10.1007/BF02165219.
↑ Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF" (PDF). J. Molecular Spectroscopy. 170: 82. Bibcode:1995JMoSp.170...82Z. doi:10.1006/jmsp.1995.1058.
↑ Template:Cite article
↑ ^9.0 ^9.1 "Atomic Weights and Isotopic Compositions for All Elements". National Institute of Standards and Technology. Retrieved 2008-09-21.

[1] Holcombe Jr., C. E.; Smith, D. D.; Lorc, J. D.; Duerlesen, W. K.; Carpenter; D. A. (October 1973). "Physical-Chemical Properties of beta-Rhombohedral Boron". High Temp. Sci. 5 (5): 349–57.

[magnet-2] Lide, David R. (ed.) (2000). Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics (PDF). CRC press. ISBN 0849304814.CS1 maint: Extra text: authors list (link)

[3] Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

[Lussac-4] Gay Lussac, J.L. & Thenard, L.J. (1808). "Sur la décomposition et la recomposition de l'acide boracique". Annales de chimie. 68: 169–174.

[Davy-5] Davy H (1809). "An account of some new analytical researches on the nature of certain bodies, particularly the alkalies, phosphorus, sulphur, carbonaceous matter, and the acids hitherto undecomposed: with some general observations on chemical theory". Philosophical Transactions of the Royal Society of London. 99: 39–104. doi:10.1098/rstl.1809.0005.

[6] Szegedi, S.; Váradi, M.; Buczkó, Cs. M.; Várnagy, M.; Sztaricskai, T. (1990). "Determination of boron in glass by neutron transmission method". Journal of Radioanalytical and Nuclear Chemistry Letters. 146 (3): 177. doi:10.1007/BF02165219.

[v1-7] Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF" (PDF). J. Molecular Spectroscopy. 170: 82. Bibcode:1995JMoSp.170...82Z. doi:10.1006/jmsp.1995.1058.

[8] Template:Cite article

[NISTic-9] 9.0 ^9.1 "Atomic Weights and Isotopic Compositions for All Elements". National Institute of Standards and Technology. Retrieved 2008-09-21.

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