Introduction
Group: 3 or III B
Atomic Weight: 138.9055
Period: 6
CAS Number: 7439-91-0
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
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
Physical Properties
Melting Point:5* 918 °C = 1191.15 K = 1684.4 °F
Electron Configuration: *[Xe] 6s2 4f1
n = 4
Electronegativity (Pauling scale):7 1.10
Specific Heat: 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)
Earth - Source Compounds: phosphates 17
External Links:
Magazines:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:17.
Boiling Point:5* 3464 °C = 3737.15 K = 6267.2 °F
Sublimation Point:5
Triple Point:5
Critical Point:5
Density:6 6.15 g/cm3
* - at 1 atm
Electron Configuration
Block: d
Highest Occupied Energy Level: 6
Valence Electrons:
Quantum Numbers:
ℓ = 3
mℓ = -3
ms = +½
Bonding
Electropositivity (Pauling scale): 2.9
Electron Affinity:8 0.47 eV
Oxidation States: +3
Work Function:9 3.40 eV = 5.4468E-19 J
Ionization Potential
eV 10
kJ/mol
1
5.5769
538.1
Ionization Potential
eV 10
kJ/mol
2
11.06
1067.1
3
19.1773
1850.3
Ionization Potential
eV 10
kJ/mol
4
49.95
4819.4
5
61.6
5943.5
Thermochemistry
Thermal Conductivity: 13.5 (W/m)/K, 27°C 12
Heat of Fusion: 6.2 kJ/mol 13 = 44.6 J/g
Heat of Vaporization: 414 kJ/mol 14 = 2980.4 J/g
State of Matter
Enthalpy of Formation (ΔHf°)15
Entropy (S°)15
Gibbs Free Energy (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
Isotopes
Nuclide
Mass 16
Half-Life 16
Nuclear Spin 16
Binding Energy
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)
STABLE
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
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 16
Reactions
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)
Abundance
Earth - Seawater: 0.0000034 mg/L 18
Earth -
Crust:
39 mg/kg = 0.0039% 18
Earth -
Total:
379 ppb 19
Mercury -
Total:
291 ppb 19
Venus -
Total:
397 ppb 19
Chondrites - Total: 0.39 (relative to 106 atoms of Si) 20
Compounds
lanthanum boride
lanthanum bromide
lanthanum carbide
lanthanum chloride
lanthanum chloride heptahydrate
lanthanum chloride trihydrate
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
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.
Sources
(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.