Boron, 5 boron (β-rhombohedral)
[1] Boron Pronunciation (BOR -on Allotropes α-, β-rhombohedral, β-tetragonal (and more ) Appearance black-brown Standard atomic weight A r, std (B) [ Boron in the periodic table
Atomic number (Z ) 5 Group group 13 (boron group) Period period 2 Block p-block Element category p-block 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 Heat of vaporization 508 kJ/mol Molar heat capacity 11.087 J/(mol·K) Vapor pressure
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
2348
2562
2822
3141
3545
4072
Atomic properties Oxidation states −5, −1, 0,[2] +3 [3] [4] acidic oxide) Electronegativity Pauling scale: 2.04 Ionization 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 Spectral lines of boronOther properties Natural occurrence primordial Crystal structure rhombohedral Speed of sound thin rod 16,200 m/s (at 20 °C) Thermal expansion β form: 5–7 µm/(m·K) (at 25 °C)[5] Thermal conductivity 27.4 W/(m·K) Electrical resistivity ~106 Ω·m (at 20 °C) Magnetic ordering diamagnetic [6] Magnetic susceptibility −6.7·10−6 cm3 /mol[6] Mohs hardness ~9.5 CAS Number 7440-42-8 History Discovery Joseph Louis Gay-Lussac and Louis Jacques Thénard [7] (30 June 1808) First isolation Humphry Davy [8] (9 July 1808) Main isotopes of boron
10 B content is 19.1–20.3% in natural samples, with the remainder being 11 B.[10] Category: Boron view · talk · edit references
B
data m.p. cat
in
calc from C
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report
ref
C
2076
—
—
K
2349
2349
0
F
3769
3769
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0
WD
input
C: 2076, K: 2349, F: 3769
comment
B
data b.p. cat
in
calc from C
diff
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C
3927
—
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K
4200
4200
0
F
7101
7101
0
max precision
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input
C: 3927, K: 4200, F: 7101
comment
References These references will appear in the article, but this list appears only on this page.
↑ Van Setten et al. 2007, pp. 2460–1↑ Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. (2012). "Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond". Science 336 (6087): 1420–2. doi :10.1126/science.1221138 . PMID 22700924 . Bibcode : 2012Sci...336.1420B . ↑ Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF" . J. Molecular Spectroscopy 170 (1): 82. doi :10.1006/jmsp.1995.1058 . Bibcode : 1995JMoSp.170...82Z . http://bernath.uwaterloo.ca/media/125.pdf . ↑ Melanie Schroeder (in de). Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden . https://www.deutsche-digitale-bibliothek.de/binary/KKUKEQ5AXZBNJVU7NJCHZB4UXT2HAGJE/full/1.pdf . ↑ 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. ↑ Jump up to: 6.06.1 Haynes, William M., ed (2016). CRC Handbook of Chemistry and Physics CRC Press . p. 4.127. ISBN 9781498754293 . ↑ Gay Lussac, J.L.; Thenard, L.J. (1808). "Sur la décomposition et la recomposition de l'acide boracique" . Annales de chimie 68 : 169–174. https://books.google.com/books?id=e6Aw616K5ysC&pg=PA169 . ↑ 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 . https://books.google.com/books?id=gpwEAAAAYAAJ&pg=PA140 . ↑ Jump up to: 9.09.1 "Atomic Weights and Isotopic Compositions for All Elements" . National Institute of Standards and Technology. http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl . Retrieved 2008-09-21 . ↑ 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 . 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 Template:Documentation
