Samarium – Europium – Gadolinium Eu Am       Full table
General
Name, Symbol, Number	Europium, Eu, 63
Chemical series	Lanthanides
Group, Period, Block	_, 6, f
Density, Hardness	5244 kg/m3, no data
Appearance	silvery white
Atomic properties
Atomic weight	151.964(1) u
Atomic radius (calc.)	185 (231) pm
Covalent radius	no data
van der Waals radius	no data
Electron configuration	[Xe]6s24f7
e-s per energy level	2, 8, 18, 25, 8, 2
Oxidation states (Oxide)	3 (mildly basic)
Crystal structure	Cubic body centered
Physical properties
State of matter	solid (__)
Melting point	1099 K (1519 °F)
Boiling point	1800 K (2781 °F)
Molar volume	28.97 cm3/mol
Heat of vaporization	143.5 kJ/mol
Heat of fusion	9.21 kJ/mol
Vapor pressure	144 Pa at 1095 K
Velocity of sound	no data
Miscellaneous
Electronegativity	1.2 (Pauling scale)
Specific heat capacity	180 J/(kg·K)
Electrical conductivity	1.12 MS /m
Thermal conductivity	13.9 W/(m·K)
1st ionization potential	547.1 kJ/mol
2nd ionization potential	1085 kJ/mol
3rd ionization potential	2404 kJ/mol
4th ionization potential	4120 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP 150Eu {syn.} 36.9 a ε 2.261 150Sm 151Eu 47.8% 151Eu is stable with 88 neutrons 152Eu {syn.} 13.516 a ε 1.874 152Sm β- 1.819 152Gd 153Eu 52.2% 153Eu is stable with 90 neutrons
SI units & STP are used except where noted.

Europium is a chemical element in the periodic table that has the symbol Eu and atomic number 63. It was named after the continent Europe.

Notable characteristics

Europium is the most reactive of the rare earth elements; it quickly oxidizes in air, and resembles calcium in its reaction with water. Like other rare earths (with the exception of lanthanum), europium ignites in air at about 150 °C to 180 °C. It is about as hard as lead and quite ductile.

Applications

There are no commercial applications for europium metal, although it has been used to dope some types of plastics to make lasers. 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 as an activator for yttrium-based phosphors. It is also being used as an agent for the manufacture of fluorescent glass.

History

Europium was first found by Paul Émile 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 Eugène-Antole Demarçay, 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.

Pure europium metal was not isolated until recent years.

Occurrence

Europium is never found in nature as the 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.

Compounds

Europium compounds include:

• Fluorides
  • EuF₂
  • EuF₃
• Chlorides
  • EuCl₂
  • EuCl₃
• Bromides
  • EuBr₂
  • EuBr₃
• Iodides
  • EuI₂
  • EuI₃
• Oxides
  • Eu₂O₃
  • Eu₃O₄
• Sulfides
  • EuS
• Selenides
  • EuSe
• Tellurides
  • EuTe
• Nitrides
  • 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). 35 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-lifes that are less than 4.7612 years, and the majority of these have half lifes that are less than 12.2 seconds. This element also has 8 meta states, with the most stable being 150m-Eu (t_½ 12.8 hours), 152m1-Eu (t_½ 9.3116 hours) and 152m2-Eu (t_½ 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.

Precautions

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.

References

• Los Alamos National Laboratory – Europium

External links

• WebElements.com – Europium
• EnvironmentalChemistry.com – Europium
• It's Elemental – Europium