Living Reference Work Entry

Encyclopedia of Geochemistry

Part of the series Encyclopedia of Earth Sciences Series pp 1-6

Date: Latest Version

Boron

  • Christophe LécuyerAffiliated withLaboratoire de Géologie de Lyon, LGL-TPE, CNRS UMR 5276, Université Claude Bernard Lyon 1 & Institut Universitaire de France Email author 

Element Data

Atomic Symbol: B

Atomic Number: 5

Atomic Weight: [10.806, 10.821]

Isotopes and Abundances: 10B: 19.9 ± 7 %, 11B: 80.1 ± 7

1 Atm Melting Point: 2,350 °C

1 Atm Boiling Point: 4,000 °C

Common Valences: +3

Ionic Radii: atomic radius = 87 pm, covalent radius = 84 pm

Pauling Electronegativity: 2.04

First Ionization Potential: 800.6 kJ.mol−1

Chondritic (CI) Abundance: 0.78 ppm (16.9 ± 2.2 atoms/106Si)

Silicate Earth Abundance: 0.26 ± 0.04 ppm

Crustal Abundance: 17 ppm

Seawater Abundance: 4.5 ppm

Core Abundance: ~0

Properties

Boron is a metalloid with a rhombohedral crystal structure. This element belongs to the group 13 and period 2 of the periodic table (Figure 1). Boron has sixteen known isotopes of which two are stable, 10B and 11B, of relative atomic mass 10.01293695(41) and 11.00930536(45) (source of data: National Institute of Standards and Technology): http://​www.​nist.​gov/​pml/​data/​comp.​cfm. Geochemists measure the relative variations in the 11B/10B of terrestrial and e ...

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