Boron

Atomic properties
Atomic number	5
Standard atomic weight	10.811(7)
Electron configuration	1s2 2s2 2p1
Physical properties
Melting point	ca. 2300 °C
Boiling point	ca. 2550 °C
Chemical properties
Electronegativity	2.04 (Pauling)
Solubility in water	insoluble
Ionization energies
1st	8.298 024(18) eV; 800.6377(17) kJ mol−1
2nd	25.154 eV; 2427.0 kJ mol−1
3rd	37.930 eV; 3659.7 kJ mol−1
4th	259.368 eV; 25025.2 kJ mol−1
5th	340.217 eV; 32826.0 kJ mol−1
Total	670.967 eV; 64738.5 kJ mol−1
Electron affinity
	0.279 743(44) eV; 26.9910(42) kJ mol−1
Atomic radii
Covalent radius	84 pm
Thermodynamic properties
Standard entropy	5.90(8) J K−1 mol−1
Enthalpy change of atomization	565(5) kJ mol−1
Entropy change of atomization	147.54(8) J K−1 mol−1
Miscellaneous
CAS number	7440-42-8
EC number	231-151-2
	Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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beryllium ← hydrogen → carbon

–
↑
H
↓
Al

Boron (symbol: B) is a chemical element.

Notes and references

↑ Boron. In NIST Chemistry WebBook; National Institute for Standards and Technology, <http://webbook.nist.gov/cgi/inchi/InChI%3DInChI=1S/B>. (accessed 21 September 2010).
↑ Allred, A. L. Electronegativity values from thermochemical data. J. Inorg. Nucl. Chem. 1961, 17 (3–4), 215–21. DOI: 10.1016/0022-1902(61)80142-5.
↑ Moore, Charlotte E. Ionization potentials and ionization limits derived from the analyses of optical spectra. Natl. Stand. Ref. Data Ser., (U.S. Natl. Bur. Stand.) 1970, 34, 1–22, <http://www.nist.gov/data/nsrds/NSRDS-NBS34.pdf>.
↑ Scheer, Michael; Bilodeau, René C.; Haugen, Harold K. Negative ion of boron: An experimental study of the ³P ground state. Phys. Rev. Lett. 1998, 80 (12), 2562–65. DOI: 10.1103/PhysRevLett.80.2562.
↑ Cordero, Beatriz; Gómez, Verónica; Platero-Prats, Ana E.; Revés, Marc; Echeverría, Jorge; Cremades, Eduard; Barragán, Flavia; Alvarez, Santiago Covalent radii revisited. Dalton Trans. 2008 (5), 2832–38. DOI: 10.1039/b801115j.
↑ Cox, J. D.; Wagman, D. D.; Medvedev, V. A. CODATA Key Values for Thermodynamics; Hemisphere: New York, 1989. ISBN 0891167587, <http://www.codata.org/resources/databases/key1.html>.

See also the corresponding article on Wikipedia.

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