BORO

Introducción

Número Atómico: 5
Grupo: 13 or III A
Peso Atómico: 10.811
Periodo: 2
Número CAS: 7440-42-8

Clasificación

Anfígeno
Halógeno
Gases nobles
Lantánido
Actínido
Tierras Raras
Platino Metal Grupo
Transuránicos
No Isótopos Estables
Sólido
Líquido
Gas
Sólido (Predicción)

Descripción

Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. The element is not found free in nature, but occurs as orthoboric acid usually in certain volcanic spring waters and as borates in borax and colemanite. Ulexite, another boron mineral, is interesting as it is nature’s own version of “fiber optics.” Important sources of boron are the ores rasorite (kernite) and tincal (borax ore). Both of these ores are found in the Mojave Desert. Tincal is the most important source of boron from the Mojave. Extensive borax deposits are also found in Turkey. Boron exists naturally as 19.9% 10B isotope and 80.1% 11B isotope. Eleven isotopes of boron are known. High-purity crystalline boron may be prepared by the vapor phase reduction of boron trichloride or tribromide with hydrogen on electrically heated filaments. The impure, or amorphous, boron, a brownish-black powder, can be obtained by heating the trioxide with magnesium powder. Boron of 99.9999% purity has been produced and is available commercially. Elemental boron has an energy band gap of 1.50 to 1.56 eV, which is higher than that of either silicon or germanium. It has interesting optical characteristics, transmitting portions of the infrared, and is a poor conductor of electricity at room temperature, but a good conductor at high temperature. Amorphous boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. By far the most commercially important boron compound in terms of dollar sales is Na2B4O7 · 5H2O. This pentahydrate is used in very large quantities in the manufacture of insulation fiberglass and sodium perborate bleach. Boric acid is also an important boron compound with major markets in textile fiberglass and in cellulose insulation as a flame retardant. Next in order of importance is borax (Na2B4O7 · 10H2O) which is used principally in laundry products. Use of borax as a mild antiseptic is minor in terms of dollars and tons. Boron compounds are also extensively used in the manufacture of borosilicate glasses. Other boron compounds show promise in treating arthritis. The isotope boron-10 is used as a control for nuclear reactors, as a shield for nuclear radiation, and in instruments used for detecting neutrons. Boron nitride has remarkable properties and can be used to make a material as hard as diamond. The nitride also behaves like an electrical insulator but conducts heat like a metal. It also has lubricating properties similar to graphite. The hydrides are easily oxidized with considerable energy liberation, and have been studied for use as rocket fuels. Demand is increasing for boron filaments, a high-strength, lightweight material chiefly employed for advanced aerospace structures. Boron is similar to carbon in that it has a capacity to form stable covalently bonded molecular networks. Carboranes, metalloboranes, phosphacarboranes, and other families comprise thousands of compounds. Crystalline boron (99%) costs about $8/g. Amorphous boron costs about $4/g. Elemental boron and the borates are not considered to be toxic, and they do not require special care in handling. However, some of the more exotic boron hydrogen compounds are definitely toxic and do require care. 1

Usos/Funciones

•metabolism of calcium, magnesium, hormones" 2
•By doping silicon with an element having three valence electrons, the conductivity is also very much enhanced. Consider what happens when silicon is doped with boron. Some of the silicon atoms in the solid are replaced by boron atoms; but because each boron atom has only three valence electrons, one of the four bonds to each boron atom has only one electron in it. We can think if this as a vacancy or "hole" in the bonding orbital. An electron from a neighboring atomcan move in to occupy this hole. Then a hole would exist on the neighboring atom, and an electron from another atom can move into it. As a result of this movement, boron-doped silicon is an electrical conductor. Because a hole is an absence of an electron, it is essentially a positive charge. Boron-doped silicon is called a p-type semiconductor, because the charge is carried by positive holes. The semiconductor behavior of doped silicon also can be explained in molecular orbital terms." 3

Magnitudes Físicas

Punto de Fusión:4*  2075 °C = 2348.15 K = 3767 °F
Punto de Ebullición:4* 4000 °C = 4273.15 K = 7232 °F
Punto de Sublimación:4 
Punto Triple:4 
Punto Crítico:4 
Densidad:5  2.34 g/cm3

* - at 1 atm

Configuración Electrónica

Configuración Electrónica: [He] 2s2 2p1
Bloque: p
Nivel Más Alto de Energía Ocupados: 2
Electrones de Valencia: 3

Números Cuánticos:

n = 2
ℓ = 1
m = -1
ms = +½

Enlace Químico

Electronegatividad (Escala de Pauling):6 2.04
Electropositivity (Escala de Pauling): 1.96
Afinidad Electrónica:7 0.279723 eV
Estados de Oxidación: +3
Función de Trabajo:8 4.75 eV = 7.6095E-19 J

Energía de Ionización   eV 9  kJ/mol  
1 8.29803    800.6
Energía de Ionización   eV 9  kJ/mol  
1 8.29803    800.6
2 25.15484    2427.1
3 37.93064    3659.7
Energía de Ionización   eV 9  kJ/mol  
4 259.37521    25025.9
5 340.2258    32826.8

Termoquímica

Capacidad Calorífica: 1.026 J/g°C 10 = 11.092 J/mol°C = 0.245 cal/g°C = 2.651 cal/mol°C
Conductividad Térmica: 27 (W/m)/K, 27ºC 11
Entalpía de Fusión: 50.2 kJ/mol 12 = 4643.4 J/g
Entalpía de Vaporización: 489.7 kJ/mol 13 = 45296.5 J/g
Estado de Agregación de la Materia Entalpía de Formación (ΔHf°)14 Entropía (S°)14 Energía Libre de Gibbs (ΔGf°)14
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 1.40 5.8576 0 0
(g) 134.5 562.748 36.65 153.3436 124.0 518.816

Isótopos

Nucleido Masa 15 Periodo de Semidesintegración 15 Espín 15 Energía de enlace nuclear
10B 10.0129370(4) ESTABLE 3+ 64.00 MeV
11B 11.0093054(4) ESTABLE 3/2- 74.87 MeV
12B 12.0143521(15) 20.20(2) ms 1+ 78.29 MeV
13B 13.0177802(12) 17.33(17) ms 3/2- 83.58 MeV
14B 14.025404(23) 12.5(5) ms 2- 84.20 MeV
15B 15.031103(24) 9.87(7) ms 3/2- 86.69 MeV
16B 16.03981(6) <190E-12 s [<0.1 MeV] 0- 87.32 MeV
17B 17.04699(18) 5.08(5) ms (3/2-) 88.87 MeV
18B 18.05617(86)# <26 ns (4-)# 87.64 MeV
19B 19.06373(43)# 2.92(13) ms (3/2-)# 89.19 MeV
6B 6.04681(75)# -0.74 MeV
7B 7.02992(8) 350(50)E-24 s [1.4(2) MeV] (3/2-) 23.08 MeV
8B 8.0246072(11) 770(3) ms 2+ 36.10 MeV
9B 9.0133288(11) 800(300)E-21 s [0.54(21) keV] 3/2- 54.71 MeV
Los valores marcados con # no se derivan exclusivamente de datos experimentales, pero al menos en parte, de las tendencias sistemáticas. Tiradas con argumentos de asignación débiles están encerrados entre paréntesis. 15

Abundancia

Tierra - Fuente Compuestos: oxides 16
Tierra - Agua de mar: 4.44 mg/L 17
Tierra -  Corteza:  10 mg/kg = 0.001% 17
Tierra -  Total:  9.6 ppb 18
Mercurio -  Total:  0.11 ppb 18
Venus -  Total:  10.0 ppb 18
Condritas - Total: 6.2 (relative to 106 atoms of Si) 19
Cuerpo Humano - Total: 0.00007% 20

Compuestos

Información Sobre Seguridad


Ficha de Datos de Seguridad - ACI Alloys, Inc.

Idiomas

Afrikáans:   Boor
Albanés:   Bor
Armenio:   Բոր
Árabe:   بورون
Arumano:   Boru
Euskera:   Boroa
Bosnio:   Bor
Bretón:   Bor
Búlgaro:   Бор
Bielorruso:   Бор
Catalán:   Bor
Chino:   硼
Córnico:   Boron
Croata:   Bor
Checo:   Bor
Danés:   Bor
Neerlandés:   Boor
Esperanto:   Borio
Estonio:   Boor
Feroés:   Bor
Finés:   Boori
Francés:   Bore
Friulano: Bôr
Frisio:   Boar
Gallego:   Boro
Georgiano:   ბორი
Alemán:   Bor
Griego:   Βοριο
Hebreo:   בור
Húngaro:   Bór
Islandés:   Bór
Irlandés:   Bórón
Italiano:   Boro
Japonés:   ホウ素
Casubio:   Bòr
Kazajo:   Бор
Coreano:   붕소
Letónico:   Bors
Lituano:   Boras
Luxemburgués:   Bor
Macedonio:   Бор
Malayo:   Boron
Maltés:   Boron
Manés:   Boron
Moksha:   Бора
Mongol:   Бор
Noruego:   Bor
Occitano:   Bòr
Osetio:   Бор
Polaco:   Bor
Portugués:   Boro
Ruso:   Бор
Gaélico Escocés:   Bòron
Serbio:   Бор
Eslovaco:   Bór
Español:   Boro
:   Baras
Suajili:   Boroni
Sueco:   Bor
Tayiko:   Bor
Tailandés:   โบรอน
Turco:   Bor
Ucraniano:   Бор
Uzbeko:   Бор
Vietnamita:   Bo
Galés:   Boron

Véase También

Enlaces Externos:

Fuentes

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:6.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 926.
(3) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 394.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(6) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(8) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(14) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(15) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(16) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(17) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(18) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(19) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(20) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.