ASTATO

Introducción

Número atómico: 85
Grupo: 17 or VII A
Peso atomico: 210
Período: 6
Número CAS: 7440-68-8

Clasificación

chalcogen
halógeno
Gas noble
Lantanoides
Actinoides
Elemento de tierras raras
Platino Metal Group
transuranium
No hay isótopos estables
Sólido
Líquido
Gas
Sólido (Predicho)

Descripción • Usos / Función

Synthesized in 1940 by D. R. Corson, K. R. MacKenzie, and E. Segre at the University of California by bombarding bismuth with alpha particles. The longest-lived isotopes, 210At, have a half-life of only 8.1 hours. Thirty-four isotopes and isomers are now known. Minute quantities of 215At, 218At, and 219At exist in equilibrium in nature with naturally occurring uranium and thorium isotopes, and traces of 217At are equilibrium with 233U and 239Np resulting from interaction of thorium and uranium with naturally produced neutrons. The total amount of astatine present in the earth’s crust, however, is less than 1 oz. Astatine can be produced by bombarding bismuth with energetic alpha particles to obtain the relatively long-lived 209–211At, which can be distilled from the target by heating it in air. Only about 0.05 mg of astatine has been prepared to date. The “time of flight” mass spectrometer has been used to confirm that this highly radioactive halogen behaves chemically very much like other halogens, particularly iodine. The interhalogen compounds AtI, AtBr, and AtCl are known to form, but it is not yet known if astatine forms diatomic astatine molecules. HAt and CH3At (methyl astatide) have been detected. Astatine is said to be more metallic that iodine, and, like iodine, it probably accumulates in the thyroid gland. Workers at the Brookhaven National Laboratory have recently used reactive scattering in crossed molecular beams to identify and measure elementary reactions involving astatine. 1

Propiedades físicas

Punto de fusion:2*  302 °C = 575.15 K = 575.6 °F
Punto de ebullición:2
Punto de sublimación:2 
Triple punto:2 
Punto crítico:2 
Densidad:   g/cm3

* - at 1 atm

Configuración electronica

Configuración electronica: [Xe] 6s2 4f14 5d10 6p5
Bloquear: p
Ocupado más alto nivel de energía: 6
Electrones de valencia: 7

Números cuánticos:

n = 6
ℓ = 1
m = 0
ms = -½

Vinculación

electronegatividad (escala de Pauling):3 2.2
Electropositivity (escala de Pauling): 1.8
Afinidad electronica:4 2.8 eV
estados de oxidación: 

termoquímica

Calor especifico: 
Conductividad térmica: 1.7 (W/m)/K, 27°C 5
Calor de fusión: 
Calor de vaporización: 
Estado de la materia Entalpía de formación (ΔHf°)6 entropía (S°)6 Energía libre de Gibbs (ΔGf°)6
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 29.0 121.336 0 0

isótopos

nucleido Masa 7 Media vida 7 spin nuclear 7 Energía de unión
191At 1.7(+11-5) ms (1/2+)
193At 192.99984(6) 28(+5-4) ms (1/2+) 1,500.58 MeV
194At 193.99873(20) ~40 ms 3+# 1,508.65 MeV
195At 194.996268(10) 328(20) ms (1/2+) 1,516.72 MeV
196At 195.99579(6) 253(9) ms 3+# 1,524.79 MeV
197At 196.99319(5) 0.390(16) s (9/2-) 1,532.86 MeV
198At 197.99284(5) 4.2(3) s (3+) 1,540.93 MeV
199At 198.99053(5) 6.92(13) s (9/2-) 1,549.01 MeV
200At 199.990351(26) 43.2(9) s (3+) 1,557.08 MeV
201At 200.988417(9) 85(3) s (9/2-) 1,574.46 MeV
202At 201.98863(3) 184(1) s (2,3)+ 1,582.53 MeV
203At 202.986942(13) 7.37(13) min 9/2- 1,590.61 MeV
204At 203.987251(26) 9.2(2) min 7+ 1,598.68 MeV
205At 204.986074(16) 26.2(5) min 9/2- 1,606.75 MeV
206At 205.986667(22) 30.6(13) min (5)+ 1,614.82 MeV
207At 206.985784(23) 1.80(4) h 9/2- 1,622.89 MeV
208At 207.986590(28) 1.63(3) h 6+ 1,630.96 MeV
209At 208.986173(8) 5.41(5) h 9/2- 1,639.03 MeV
210At 209.987148(8) 8.1(4) h (5)+ 1,647.10 MeV
211At 210.9874963(30) 7.214(7) h 9/2- 1,655.18 MeV
212At 211.990745(8) 0.314(2) s (1-) 1,653.93 MeV
213At 212.992937(5) 125(6) ns 9/2- 1,662.00 MeV
214At 213.996372(5) 558(10) ns 1- 1,670.07 MeV
215At 214.998653(7) 0.10(2) ms 9/2- 1,678.15 MeV
216At 216.002423(4) 0.30(3) ms 1- 1,676.90 MeV
217At 217.004719(5) 32.3(4) ms 9/2- 1,684.97 MeV
218At 218.008694(12) 1.5(3) s 1-# 1,693.05 MeV
219At 219.011162(4) 56(3) s 5/2-# 1,691.80 MeV
220At 220.01541(6) 3.71(4) min 3(-#) 1,699.87 MeV
221At 221.01805(21)# 2.3(2) min 3/2-# 1,707.94 MeV
222At 222.02233(32)# 54(10) s 1,706.70 MeV
223At 223.02519(43)# 50(7) s 3/2-# 1,714.77 MeV
Los valores marcados con # no son puramente derivan de los datos experimentales, pero al menos en parte, de las tendencias sistemáticas. Hace girar con débiles argumentos de asignación se incluyen entre paréntesis. 7

Abundancia

Información de seguridad


Ficha de datos de seguridad de materiales - ACI Alloys, Inc.

Para más información

Enlaces externos:

Fuentes

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:4-4:5.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(7) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(8) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).