Introducción
Grupo: 3 or III B
Peso atomico: 138.9055
Período: 6
Número CAS: 7439-91-0
Clasificación
No hay isótopos estables
Sólido
Líquido
Gas
Sólido (Predicho)
Descripción • Usos / Función
Mosander in 1839 extracted a new earth lanthana, from impure cerium nitrate, and recognized the new element. Lanthanum is found in rare-earthminerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages upto 25 and 38%, respectively. Misch metal, used in making lighter flints, contains about 25% lanthanum. Lanthanum was isolated in relatively pureform in 1923. Iron-exchange and solvent extraction techniques have led to much easier isolation of the so-called “rare-earth” elements. The availabilityof lanthanum and other rare earths has improved greatly in recent years. The metal can be produced by reducing the anhydrous fluoride with calcium.Lanthanum is silvery white, malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidizesrapidly when exposed to air. Cold water attacks lanthanum slowly, and hot water attacks it much more rapidly. The metal reacts directly with elementalcarbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and with halogens. At 310°C, lanthanum changes from a hexagonal to a face-centeredcubic structure, and at 865°C it again transforms into a body-centered cubic structure. Natural lanthanum is mixture of two isotopes, one of which isstable and one of which is radioactive with a very long half-life. Twenty nine other radioactive isotopes are recognized. Rare-earth compoundscontaining lanthanum are extensively used in carbon lighting applications, especially by the motion picture industry for studio lighting and projection.This application consumes about 25% of the rare-earth compounds produced. La2O3 improves the alkali resistance of glass, and is used in makingspecial optical glasses. Small amounts of lanthanum, as an additive, can be used to produce nodular cast iron. There is current interest in hydrogensponge alloys containing lanthanum. These alloys take up to 400 times their own volume of hydrogen gas, and the process is reversible. Heat energyis released every time they do so; therefore these alloys have possibilities in energy conservation systems. Lanthanum and its compounds have a lowto moderate acute toxicity rating; therefore, care should be taken in handling them. The metal costs about $2/g (99.9%). 1
• "The battery in a single Toyota Prius contains more than 20 pounds of the rare earth element lanthanum" 2
• "Night-vision goggles require lanthanum" 3
• "catalyst in refining oil to gasoline" 4
Propiedades físicas
Punto de fusion:5* 918 °C = 1191.15 K = 1684.4 °F
Configuración electronica: *[Xe] 6s2 4f1
n = 4
electronegatividad (escala de Pauling):7 1.10
Calor especifico: 0.195 J/g°C 11 = 27.087 J/mol°C = 0.047 cal/g°C = 6.474 cal/mol°C
2 La (s) + 6 H2O (g) → 2 La(OH)3 (aq) + 3 H2 (g)
Tierra - Los compuestos de origen: phosphates 17
Enlaces externos:
revistas:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:17.
Punto de ebullición:5* 3464 °C = 3737.15 K = 6267.2 °F
Punto de sublimación:5
Triple punto:5
Punto crítico:5
Densidad:6 6.15 g/cm3
* - at 1 atm
Configuración electronica
Bloquear: d
Ocupado más alto nivel de energía: 6
Electrones de valencia:
Números cuánticos:
ℓ = 3
mℓ = -3
ms = +½
Vinculación
Electropositivity (escala de Pauling): 2.9
Afinidad electronica:8 0.47 eV
estados de oxidación: +3
Función del trabajo:9 3.40 eV = 5.4468E-19 J
potencial de ionización
eV 10
kJ/mol
1
5.5769
538.1
potencial de ionización
eV 10
kJ/mol
2
11.06
1067.1
3
19.1773
1850.3
potencial de ionización
eV 10
kJ/mol
4
49.95
4819.4
5
61.6
5943.5
termoquímica
Conductividad térmica: 13.5 (W/m)/K, 27°C 12
Calor de fusión: 6.2 kJ/mol 13 = 44.6 J/g
Calor de vaporización: 414 kJ/mol 14 = 2980.4 J/g
Estado de la materia
Entalpía de formación (ΔHf°)15
entropía (S°)15
Energía libre de Gibbs (ΔGf°)15
(kcal/mol)
(kJ/mol)
(cal/K)
(J/K)
(kcal/mol)
(kJ/mol)
(s)
0
0
13.6
56.9024
0
0
(g)
103.0
430.952
43.56
182.25504
94.07
393.58888
isótopos
nucleido
Masa 16
Media vida 16
spin nuclear 16
Energía de unión
117La
116.95007(43)#
23.5(26) ms
(3/2+,3/2-)
946.32 MeV
118La
117.94673(32)#
200# ms
963.71 MeV
119La
118.94099(43)#
1# s
11/2-#
971.78 MeV
120La
119.93807(54)#
2.8(2) s
989.17 MeV
121La
120.93301(54)#
5.3(2) s
11/2-#
997.24 MeV
122La
121.93071(32)#
8.6(5) s
1,005.31 MeV
123La
122.92624(21)#
17(3) s
11/2-#
1,022.70 MeV
124La
123.92457(6)
29.21(17) s
(7-,8-)
1,030.77 MeV
125La
124.920816(28)
64.8(12) s
(11/2-)
1,038.84 MeV
126La
125.91951(10)
54(2) s
(5)(+#)
1,056.23 MeV
127La
126.916375(28)
5.1(1) min
(11/2-)
1,064.30 MeV
128La
127.91559(6)
5.18(14) min
(5+)
1,072.37 MeV
129La
128.912693(22)
11.6(2) min
3/2+
1,080.44 MeV
130La
129.912369(28)
8.7(1) min
3(+)
1,088.51 MeV
131La
130.91007(3)
59(2) min
3/2+
1,096.58 MeV
132La
131.91010(4)
4.8(2) h
2-
1,104.65 MeV
133La
132.90822(3)
3.912(8) h
5/2+
1,122.04 MeV
134La
133.908514(21)
6.45(16) min
1+
1,130.11 MeV
135La
134.906977(11)
19.5(2) h
5/2+
1,138.18 MeV
136La
135.90764(6)
9.87(3) min
1+
1,146.25 MeV
137La
136.906494(14)
6(2)E+4 a
7/2+
1,154.32 MeV
138La
137.907112(4)
1.02(1)E+11 a
5+
1,162.40 MeV
139La
138.9063533(26)
ESTABLE
7/2+
1,170.47 MeV
140La
139.9094776(26)
1.6781(3) d
3-
1,178.54 MeV
141La
140.910962(5)
3.92(3) h
(7/2+)
1,177.29 MeV
142La
141.914079(6)
91.1(5) min
2-
1,185.37 MeV
143La
142.916063(17)
14.2(1) min
(7/2)+
1,193.44 MeV
144La
143.91960(5)
40.8(4) s
(3-)
1,201.51 MeV
145La
144.92165(10)
24.8(20) s
(5/2+)
1,200.27 MeV
146La
145.92579(8)
6.27(10) s
2-
1,208.34 MeV
147La
146.92824(5)
4.015(8) s
(5/2+)
1,216.41 MeV
148La
147.93223(6)
1.26(8) s
(2-)
1,215.16 MeV
149La
148.93473(34)#
1.05(3) s
5/2+#
1,223.24 MeV
150La
149.93877(43)#
510(30) ms
(3+)
1,231.31 MeV
151La
150.94172(43)#
300# ms [>300 ns]
5/2+#
1,230.06 MeV
152La
151.94625(43)#
200# ms [>300 ns]
1,238.13 MeV
153La
152.94962(64)#
150# ms [>300 ns]
5/2+#
1,246.21 MeV
154La
153.95450(64)#
100# ms
1,244.96 MeV
155La
154.95835(86)#
60# ms
5/2+#
1,253.03 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. 16
reacciones
2 La (s) + 3 F2 (g) → 2 LaF3 (s)
2 La (s) + 3 Cl2 (g) → 2 LaCl3 (s)
2 La (s) + 3 Br2 (g) → 2 LaBr3 (s)
2 La (s) + 3 I2 (g) → 2 LaI3 (s)
Abundancia
Tierra - Agua de mar: 0.0000034 mg/L 18
Tierra -
Corteza:
39 mg/kg = 0.0039% 18
Tierra -
Total:
379 ppb 19
Planeta mercurio) -
Total:
291 ppb 19
Venus -
Total:
397 ppb 19
condritas - Total: 0.39 (relative to 106 atoms of Si) 20
Compuestos
lanthanum boride
lanthanum bromide
lanthanum carbide
lanthanum chloride
lanthanum chloride heptahydrate
lanthanum chloride trihydrate
Información de seguridad
Ficha de datos de seguridad de materiales - ACI Alloys, Inc.
Para más información
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
(1) Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, pp 136-145.
Fuentes
(2) - Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, p 138.
(3) - Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, p 140.
(4) - Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, p 143.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(7) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(9) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(15) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(16) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(17) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(18) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(19) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(20) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.