Europium
Title: Europium
CAS Registry Number: 7440-53-1
Literature References: Eu; at. wt 151.964; at. no. 63; valences 2, 3. A lanthanide; belongs to cerium group of rare earth metals. Naturally occurring isotopes (mass numbers): 151 (47.8%); 153 (52.2%); known artificial radioactive isotopes: 138-150; 152; 154-160. Abundance in earth's crust: 1.06-2.1 ppm. Commercially important sources are the rare earth minerals monazite and bastnaesite; also found in gadolinite. Has been detected spectroscopically in the sun and in certain stars. Discovered and prepd as the oxide: Demarçay, Compt. Rend. 122, 728 (1896); 130, 1019, 1469 (1900); 132, 1484 (1901). Separation: Spedding et al., J. Am. Chem. Soc. 76, 2557 (1954); by paper chromatography: Lederer, Nature 176, 462 (1953). Toxicity study: Haley, J. Pharm. Sci. 54, 663 (1965). Reviews of prepn, properties and compds: The Rare Earths, F. H. Spedding, A. H. Daane, Eds. (Krieger, Huntington, N.Y., 1971, reprint of 1961 ed.) 641 pp; S. P. Sinha, Europium (Springer, New York, 1967) 164 pp; Hulet, Bode, "Separation Chemistry of the Lanthanides and Transplutonium Actinides" in MTP Int. Rev. Sci.: Inorg. Chem., Ser. One vol. 7, K. W. Bagnall, Ed. (University Park Press, Baltimore, 1972) pp 1-45; Moeller, "The Lanthanides" in Comprehensive Inorganic Chemistry vol. 4, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1-101; F. H. Spedding in Kirk-Othmer Encyclopedia of Chemical Technology vol. 19 (John Wiley & Sons, New York, 3rd ed., 1982) pp 833-854; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 1423-1449. Brief review of properties: G. T. Seaborg, Radiochim. Acta 61, 115-122 (1993).
Properties: Body-centered cubic crystal lattice; d 5.244; mp 826°. bp 1429°. Heat of fusion: 9.221 kJ/mol. Heat of sublimation (25°): 144.7 kJ/mol. Sol in liq ammonia. Shows two reduction potentials -0.710 and -2.510 v. (referred to a normal calomel electrode): Noddack, Brukl, Angew. Chem. 50, 362 (1937); gives two definite series of salts, in one the metal is divalent, and in the other it is trivalent.
Melting point: mp 826°
Boiling point: bp 1429°
Density: d 5.244
 
Derivative Type: Sesquioxide
Additional Names: Europia
Molecular Formula: Eu2O3
Molecular Weight: 351.93
Percent Composition: Eu 86.36%, O 13.64%
Properties: Pink powder, d 7.42, prepd by heating the hydroxide, nitrate, oxalate or sulfate at 1600°. The oxide of the divalent metal is prepd by reduction of the sesquioxide at elevated temp.
Density: d 7.42
 
Derivative Type: Hydroxide
Molecular Formula: Eu(OH)3
Molecular Weight: 202.99
Percent Composition: Eu 74.86%, O 23.65%, H 1.49%
Properties: Prepd by adding ammonia or an alkali hydroxide to a soln of an europic salt.
 
Derivative Type: Europic chloride
Molecular Formula: EuCl3
Molecular Weight: 258.32
Percent Composition: Eu 58.83%, Cl 41.17%
Properties: Greenish-yellow needles; mp 623° in nitrogen (in a closed tube), d35 4.471, prepd by passing sulfur chloride over the heated oxide at 200-500°. LD50 of trichloride in mice: 550 mg/kg i.p.; 5 g/kg orally (Haley).
Melting point: mp 623° in nitrogen (in a closed tube)
Density: d35 4.471
Toxicity data: LD50 of trichloride in mice: 550 mg/kg i.p.; 5 g/kg orally (Haley)
 
Derivative Type: Europous chloride
Molecular Formula: EuCl2
Molecular Weight: 222.87
Percent Composition: Eu 68.19%, Cl 31.81%
Properties: Prepd by reduction of EuCl3 with hydrogen at 600°. White amorphous powder, sol in water.
 
Derivative Type: Europic sulfate
Molecular Formula: Eu2(SO4)3
Molecular Weight: 592.12
Percent Composition: Eu 51.33%, S 16.25%, O 32.42%
Properties: Octahydrate, a pinkish cryst solid, prepd by dissolving the oxide in sulfuric acid. Soly in water: 2.56 parts per 100 parts at 20°, 1.93 parts per 100 parts at 40°. On heating at 375° yields the anhydr sulfate.
 
Derivative Type: Europic nitrate
Molecular Formula: Eu(NO3)3
Molecular Weight: 337.98
Percent Composition: Eu 44.96%, N 12.43%, O 42.60%
Properties: Hexahydrate, mp 85° in its water of crystallization (sealed tube). LD50 in rats (mg/kg): 210 i.p.; >5000 orally (Haley).
Melting point: mp 85° in its water of crystallization (sealed tube)
Toxicity data: LD50 in rats (mg/kg): 210 i.p.; >5000 orally (Haley)
 
Derivative Type: Europous sulfate
Molecular Formula: EuSO4
Molecular Weight: 248.03
Percent Composition: Eu 61.27%, S 12.93%, O 25.80%
Properties: Colorless crystals. Insol in water and in dil acids. Prepd by electrolytic reduction of europic salts.
 
Use: The salts in cathode ray tube coatings for color television receivers. Eu has a very high cross-section for the capture of thermal neutrons which is of value in the construction of electric atomic power stations. Organic derivs as shift reagents in NMR spectroscopy: C. C. Hinckley, J. Am. Chem. Soc. 91, 5160 (1969); R. E. Sievers, Nuclear Magnetic Resonance Shift Reagents (Academic Press, New York, 1973).

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