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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	ΔH_sub/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	Remarks
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

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