63
  Eu  
151.964000
Europium

Name: Europium
Symbol: Eu
Atomic Number: 63
Atomic Weight: 151.964000
Family: Rare Earth Elements
CAS RN: 7440-53-1
Description: A silvery white, most reactive rare earth metal.
State (25C): Solid
Oxidation states: +2, +3

Molar Volume: 28.98 cm3/mole
Valence Electrons: 4f76s2

Boiling Point:  1870K, 1597C, 2907F
Melting Point:
1095K, 822C, 1512F
Electrons Energy Level: 2, 8, 18, 25, 8, 2
Isotopes: 36 + 2 Stable + 8 meta states
Heat of Vaporization: 143.5 kJ/mol
Heat of Fusion: 9.21 kJ/mol
Density: 5.24g/cm3 @ 300K
Specific Heat: 0.18 J/gK
Atomic Radius: 2.56
Ionic Radius: 0.947
Electronegativity: 1.2 (Pauling),  1.01 (Allrod Rochow)
Vapor Pressue: 144 Pa @ 822C
57
La
138.9
58
Ce
140.1
59
Pr
140.9
60
Nd
144.2
61
Pm
(145)
62
Sm
150.4
63
Eu
152.0
64
Gd
157.3
65
Tb
158.9
66
Dy
162.5
67
Ho
164.9
68
Er
167.3
69
Tm
168.9
70
Yb
173.0
71
Lu
175.0

1s2 2s2p6 3s2p6d10 4s2p6d10f7 5s2p6 6s2

History

Europium was first found by Paul Emile Lecoq de Boisbaudran in 1890, who obtained basic fraction from samarium-gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium; however, the discovery of europium is generally credited to French chemist Eugene-Antole Demarcay, who suspected samples of the recently discovered element samarium were contaminated with an unknown element in 1896 and who was able to isolate europium in 1901.

Named for the continent of Europe, the element ranks thirteenth in abundance among the rare earth metals, but there is more of it than silver and gold combined.

Characteristics

The pure metal was not isolated until recent years.  Europium is now prepared by, mixing Eu2O3 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.  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.  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. 

Generally refined from monazite sand, the pure metal has few applications, but you would find it less interesting to read this without some of its compounds which are used as activators and red phosphors in color CRT screens for television and computers.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f7
5s2 5p6
6s2

It instantly oxidizes in air, and resembles calcium in its reaction with water; deliveries of the metal element in solid form even under mineral oil are rarely shiny.  Europium ignites in air at about 150C to 180C.  It is about as hard as lead and quite ductile.

Occurrence

Europium is never found in nature as a free element; however, there are many minerals containing europium, with the most important sources being bastnasite and monazite.   Europium has also been identified in the spectra of the sun and certain stars.

Applications

There are few commercial applications for europium metal, although it has been used to dope some types of glass to make lasers, as well as being used for screening for Down Snydrome and some other genetic diseases.  Due to its ability to absorb neutrons, it is also being studied for use in nuclear reactors. Europium oxide (Eu2O3) is widely used as a red phosphor in television sets and fluorescent lamps, and as an activator for yttrium-based phosphors.  It is also being used as an agent for the manufacture of fluorescent glass. Europium fluorescence is used to interogate biomolecular interactions in drug-discovery screens.  It is also used in the anti-counterfeiting phosphors in Euro banknotes.

Europium is commonly included in trace element studies in geochemistry and petrology to understand the processes that form igneous rocks (rocks that cooled from magma or lava).   The nature of the europium anomaly found is used to help reconstruct the relationships within a suite of igneous rocks.

Compounds

Europium (II) compounds tend to predominate, in contrast to most lanthanides (which generally form compounds with an oxidation state of +3). Europium (II) chemistry is very similar to barium (II) chemistry, as they have similar ionic radii.

Florides Chlorides Bromides
EuF2
EuF3
EuCl2
EuCl3
EuBr2
EuBr3
Iodides Oxides Sulfides
EuI2
EuI3
Eu2O3
Eu3O4
EuS
Selenides Tellurides Nitrides
EuSe EuTe EuN

Isotopes

Naturally occurring europium is composed of 2 stable isotopes, 151-Eu and 153-Eu, with 153-Eu being the most abundant (52.2% natural abundance).  36 radioisotopes have been characterized, with the most stable being 150-Eu with a half-life of 36.9 years, 152-Eu with a half-life of 13.516 years, and 154-Eu with a half-life of 8.593 years. All of the remaining radioactive isotopes have half-lives that are less than 4.7612 years, and the majority of these have half lives that are less than 12.2 seconds. This element also has 8 meta states, with the most stable being 150m-Eu (t 12.8 hours), 152m1-Eu (t 9.3116 hours) and 152m2-Eu (t 96 minutes).

The primary decay mode before the most abundant stable isotope, 153-Eu, is electron capture, and the primary mode after is beta minus decay.  The primary decay products before 153-Eu are element Sm (samarium) isotopes and the primary products after are element Gd (gadolinium) isotopes.

atom.gif (700 bytes)

Isotope  
Atomic Mass
 
Half-Life
130Eu 129.96357 1.1 ms
131Eu 130.95775 17.8 ms
132Eu 131.95437 ~100 ms
133Eu 132.94924 ~200 ms
134Eu 133.94651 0.5 seconds
135Eu 134.94182 1.5 seconds
136Eu 135.93960 3.3 seconds
136mEu   3.8 seconds
137Eu 136.93557 8.4 seconds
138Eu 137.93371 12.1 seconds
139Eu 138.929792 17.9 seconds
140Eu 139.92809 1.51 seconds
141Eu 140.924931 40.7 seconds
141mEu   2.7 seconds
142Eu 141.92343 2.36 seconds
142mEu   1.223 minutes
143Eu 142.920298 2.59 minutes
144Eu 143.918817 10.2 seconds
145Eu 144.916265 5.93 days
146Eu 145.917206 4.61 days
147Eu 146.916746 24.1 days
148Eu 147.918086 54.5 days
149Eu 148.917931 93.1 days
150Eu 149.919702 36.9 years
150mEu   12.8 hours
151Eu 150.9198502 Stable
152Eu 151.9217445 13.537 years
152m1Eu   9.3116 hours
152m5Eu   96 minutes
153Eu 152.9212303 Stable
154Eu 153.9229792 8.593 years
154m1Eu   46.3 minutes
155Eu 154.9228933 4.7611 years
156Eu 155.924752 15.19 days
157Eu 156.925424 15.18 hours
158Eu 157.92785 45.9 minutes
159Eu 158.929089 18.1 minutes
160Eu 159.93197 38 seconds
161Eu 160.93368 26 seconds
162Eu 161.93704 10.6 seconds
163Eu 162.93921 ~6 seconds
164Eu 163.94299 ~2 seconds
165Eu 164.94572 ~1 seconds
166Eu 165.94997 ~400 ms
167Eu 166.95321 ~200 ms

Precautions

80px-Flammable.jpg (2186 bytes) The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals. The metal dust presents a fire and explosion hazard. Europium has no known biological role.

atom.gif (700 bytes)

Europium Data

 

Atomic Structure

Atomic Radius: 2.56
Atomic Volume cm3/mol : 28.9
Covalent Radius: 1.85
Crystal Structure: Body-Centered Cubic (BCC)
Ionic Radius: 0.947

Chemical Properties

Electrochemical Equivalents: 1.8899g/amp-hr
Electron Work Function: 2.5eV
Electronegativity: 1.2 (Pauling),  1.01 (Allrod Rochow)
Heat of Fusion: 9.21 kJ/mol
First Ionization Potential: 5.67
Second Ionization Potential: 11.245
Third Ionization Potential: 24.926
Valence Electron Potential: 45.6 -eV
Ionization Energy (eV): 5.670 eV

Physical Properties

Atomic Mass Average: 151.965
Boiling Point: 1802K, 1529C or 2784F
Melting Point: 1095K, 822C or 1512F
Heat of Vaporization: 143.5 kJ/mol
Coefficient of Lineal Thermal Expansion/K-1: 32E-6
Electrical Conductivity: 0.0112 106/cm
Thermal Conductivity: 0.139 W/cmK
Density: 5.24g/cm3 @ 300K
Enthalpy of Atomization: 180 kJ/mole @ 25C
Enthalpy of Fusion: 9.21 kJ/mole
Enthalpy of Vaporization: 143.5 kJ/mole
Molar Volume: 28.98 cm3/mole
Specific Heat: 0.18 J/gK or 0.176 J/g mol
Vapor Pressue: 144 Pa @ 822C
Estimated Crustal Abundance: 2.0 milligrams per kilogram
Estimated Oceanic Abundance: 1.310-7 milligrams per liter

Miscellaneous

Evaporation Heat (kJ/mol): 176
First Ionizing Energy (kJ/mol): 546.9
Lattice Constant (): 4.610