Europium

Europium - Eu

CAS: 7440-53-1
Description: Soft, silvery metal
Classification: Rare Earth (Lanthanide)
Date of Discovery: 1901
Discoverer: Eugene Demarcay
Name Origin: Europe

Atomic Number: 63
Number of Neutrons: 89
Atomic Mass: 151.964 amu
Melting Point: 822.0 °C
Boiling Point: 1597.0 °C
Density (293 K): 5.259 g/cm³
Atomic volume: 28.9 cm³/mol
Electrical resistivity: 0.0112 10^-6/cm

Thermal conductivity: 0.139 W/cmK
Enthalpy of atomization: 180 kJ/mol (est.)
Enthalpy of vaporization: 143.50 kJ/mol
Enthalpy of fusion: 9.210 kJ/mol
Specific heat capacity: 0.18 J/gK

Energy levels: 2-8-18-25-8-2
Electron configuration: [Xe]4f ⁷6s²
Crystal Structure: Cubic body centered
Atomic radius: 2.56 Å
Covalent radius: 1.85 Å
Oxidation States: +2, +3
Electronegativity, Pauling:
Electron affinity: 1.2
First ionization energy: 5.67 eV
2nd ionization energy: 11.245 eV
3rd ionization energy: 24.926 eV
Polarizability: 22.7 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
¹³⁴Eu	0.5 s	EC, ⁺
¹³⁵Eu	134.942	1.5 s	EC, ⁺
^136mEu	3.2 s	7+
¹³⁶Eu	135.940	3.9 s	EC, ⁺	1+
¹³⁷Eu	136.935	11 s	EC	11/2-
¹³⁸Eu	137.9335	12 s	EC, ⁺	7+
¹³⁹Eu	138.9298	18 s	EC, ⁺
^140mEu	0.125 s	EC, ⁺
¹⁴⁰Eu	139.9285	1.51 s	EC, ⁺	1-
^141mEu	3.0 s	⁺; EC; IT
¹⁴¹Eu	140.9244	40 s	⁺; EC	5/2+
^142mEu	1.22 m	⁺; EC	8-
¹⁴²Eu	141.9231	2.4 s	^-; EC	1+
¹⁴³Eu	142.92017	2.62 m	⁺; EC	5/2+
¹⁴⁴Eu	143.91879	10.2 s	⁺; EC	1+
¹⁴⁵Eu	144.916263	5.93 d	⁺; EC	5/2+
¹⁴⁶Eu	145.91720	4.57 d	⁺; EC	4-
¹⁴⁷Eu	146.916742	24.4 d	EC; ⁺	5/2+
¹⁴⁸Eu	147.91815	54.5 d	EC	5-
¹⁴⁹Eu	148.91792	93.1 d	EC	5/2+
¹⁵⁰Eu	149.91970	36 y	EC	5-
^151mEu	12.8 h	^-; ⁺; EC	0-
¹⁵¹Eu	47.8(15)	150.919846	Stable	5/2+
^152m2Eu	1.60 h	IT	8-
^152m1Eu	9.30 h	^-; EC	0-
¹⁵²Eu	151.927141	13.5 y	EC; ^-	3-
¹⁵³Eu	52.2(15)	152.921227	Stable	5/2+
^154mEu	46.1 m	IT	8-
¹⁵⁴Eu	153.922976	8.59 y	^-; EC	3-
¹⁵⁵Eu	154.922890	4.76 y	^-	5/2+
¹⁵⁶Eu	155.92475	15.2 d	^-	1+
¹⁵⁷Eu	156.92542	15.13 h	^-	(5/2+)
¹⁵⁸Eu	157.9278	45.9 m	^-	(1-)
¹⁵⁹Eu	158.92909	18.1 m	^-	(5/2+)
¹⁶⁰Eu	159.9315	38 s	^-	(0-)
¹⁶¹Eu	160.9337	27 s	^-
¹⁶²Eu	161.9370	11 s	^-
In 1890 Boisbaudran obtained basic fractions from samarium-gadolinium concentrates which had spark spectral lines not accounted for by samarium or gadolinium. These lines subsequently have been shown to belong to europium. The discovery of europium is generally credited to Demarcay, who separated the rare earth in reasonably pure form in 1901. The pure metal was not isolated until recent years. Europium is now prepared by mixing Eu₂O₂ with a 10%-excess of lanthanum metal and heating the mixture in a tantalum crucible under high vacuum. The element is collected as silvery-white metallic deposit on the walls of the crucible. As with other rare-earth metals, except for lanthanum, europium ignites in air at about 150 to 180 °C. Europium is about as hard as lead and is quite ductile. It is the most reactive of the rare-earth metals, quickly oxidizing in air. It resembles calcium in its reaction with water. Bastnasite and monazite are the principal ores containing europium. Europium has been identified spectroscopically in the sun and certain stars. Europium isotopes are good neutron absorbers and are being studied for use in nuclear control applications. Europium oxide is now widely used as a phosphor activator and europium-activated yttrium vanadate is in commercial use as the red phosphor in color TV tubes. Europium-doped plastic has been used as a laser material. With the development of ion-exchange techniques and special processes, the cost of the metal has been greatly reduced in recent years. Natural europium contains two stable isotopes. Thirty-five other radioactive isotopes and isomers are known. Europium is one of the rarest and most costly of the rare-earth metals. LINKS: Arris International Rare Earth Metals Chiral europium or terbium complexes as probes Research groups working with atom traps Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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