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Boron in the periodic table

Boron, shown here in the form of its β-rhombohedral phase (its most thermodynamically stable allotrope)[1]
General properties
Name, symbol, number boron, B, 5
Pronunciation /ˈbɔːrɒn/
Element category metalloid
Group, period, block Template:Infobox element/group, 2, p
Standard atomic weight 10.81(1)
Electron configuration [He] 2s2 2p1
2, 3
Physical properties
Phase solid
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
[[Enthalpy of vaporization|Heat of Template:Engvar]] 508 kJ·mol−1
Molar heat capacity 11.087 J·mol−1·K−1
[[Vapor pressure|Template:Engvar 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 3, 2, 1[2]
(mildly acidic oxide)
Electronegativity 2.04 (Pauling scale)
[[ionization energy|Template:Engvar energies]]
1st: 800.6 kJ·mol−1
2nd: 2427.1 kJ·mol−1
3rd: 3659.7 kJ·mol−1
Atomic radius 90 pm
Covalent radius 84±3 pm
Van der Waals radius 192 pm
Crystal structure Template:Infobox element/crystal structure wikilink
Magnetic ordering diamagnetic[3]
Electrical resistivity (20 °C) ~106 Ω·m
Thermal conductivity 27.4 W·m−1·K−1
Thermal expansion (25 °C) (β form) 5–7[4] µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 16,200 m·s−1
Mohs hardness ~9.5
CAS registry number 7440-42-8
Discovery Joseph Louis Gay-Lussac and Louis Jacques Thénard[5] (30 June 1808)
First isolation Humphry Davy[6] (9 July 1808)
Most stable isotopes
Main article: Isotopes of boron
iso NA half-life DM DE (MeV) DP

Template:Elementbox isotopes stable[7] Template:Elementbox isotopes stable[7]

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.[8]
· references
Boron in a tube

Boron ek chemical element hae jiske chemical symbol B, aur atomic number 5 hae.

[badlo | source ke badlo]


[badlo | source ke badlo]


  1. Van Setten et al. 2007, pp. 2460–1
  2. Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF". J. Molecular Spectroscopy 170: 82. doi:10.1006/jmsp.1995.1058. http://bernath.uwaterloo.ca/media/125.pdf.
  3. Lide, David R. (ed.) (2000). Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics. CRC press. ISBN 0849304814. http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elementmagn.pdf.
  4. 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.
  5. Gay Lussac, J.L. and Thenard, L.J. (1808) "Sur la décomposition et la recomposition de l'acide boracique," Annales de chimie [later: Annales de chemie et de physique], vol. 68, pp. 169–174.
  6. 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: 33–104. http://books.google.com/books?id=gpwEAAAAYAAJ&pg=PA140#v=onepage&q&f=false.
  7. 7.0 7.1 "Atomic Weights and Isotopic Compositions for All Elements". National Institute of Standards and Technology. Retrieved 2008-09-21.
  8. 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.