Boron, B

Boron is a chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent nonmetallic element which occurs abundantly in the evaporite ores borax and ulexite. Boron is never found as a free element in nature.

Several allotropes of boron exist; amorphous boron is a brown powder, though crystalline boron is black, hard (9.3 on Mohs' scale), and a weak conductor at room temperature. Elemental boron is used as a dopant in the semiconductor industry, while boron compounds play important roles as light structural materials, nontoxic insecticides and preservatives, and reagents for chemical synthesis.

Boron is an essential plant nutrient, although higher soil concentrations of boron may also be toxic to plants. As an ultratrace element, boron is necessary for the optimal health of rats and presumably other mammals, though its physiological role in animals is poorly understood.

Technical Data
Symbol B DenSity/gcm-3 (β rhombohedral) 2.35
Atomic number 5 (α rhombohedral) 2.45
No. of naturally occurring isotopes 2 Melting point /°C (β rhombohedral) 2180
Atomic weight 10.81 Boiling point /°C (β rhombohedral) ~3650
Electronic configuration [He] 2s22p1 ΔHsub/kJmol-1 570
Ionization energy/kJmol -1 800.5 Electronegativity χ 2
II 2426.5 Electrical conductivity  
III 3658.7 (25°C)/ohm-1 cm-1 l.5x 10-6
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
1278 Sublimes 1548 Sublimes 1797 Sublimes Excellent Graphite & Vitreous Graphite - Graphite Material explodes with rapid cooling. Forms carbide with container.

Evaporation Materials
B4-5002-M pieces 3-8mm
B4-5006-M pieces 1-3mm
B4-5008-M pieces 5-30mm
Powder
B4-10000-P -60 mesh
B4-10001-P 5 microns or less
B4-10002-P -325 mesh