Europium

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Europium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent Europe. Europium is the most reactive of the rare earth elements; it rapidly oxidizes in air, and resembles calcium in its reaction with water; deliveries of the metal element in solid form, even when coated with a protective layer of mineral oil, are rarely shiny. Europium ignites in air at about 150 °C to 180 °C. It is about as hard as lead and quite ductile.

 

General
Name, Symbol, Number europium, Eu, 63
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white
Standard atomic weight 151.964(1) g·mol-1
Electrons per shell 2, 8, 18, 25, 8, 2
Physical properties
Phase solid
Density (near r.t.) 5.264 g·cm−3
Liquid density at m.p. 5.13 g·cm−3
Melting point 1099K
(826°C, 1519°F)
Boiling point 1802K
(1529°C, 2784°F)
Heat of fusion 9.21 kJ·mol-1
Heat of vaporization 176 kJ·mol-1
Heat capacity (25°C) 27.66 J·mol-1·K-1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 863 957 1072 1234 1452 1796
Atomic properties
Crystal structure simple cubic (body centered)
Oxidation states 3,2
(mildly basic oxide)
Electronegativity  1.2 (Pauling scale)
Ionization energies
(more)		 1st: 547.1 kJ·mol-1
2nd: 1085 kJ·mol-1
3rd: 2404 kJ·mol-1
Atomic radius 185 pm
Atomic radius (calc.) 231 pm
Miscellaneous
Magnetic ordering no data
Electrical resistivity (r.t.) (poly) 0.900 µΩ·m
Thermal conductivity (300K) est. 13.9 W·m-1·K-1
Thermal expansion (r.t.) (poly)
35.0 µm/(m·K)
Young's modulus 18.2 GPa
Shear modulus 7.9 GPa
Bulk modulus 8.3 GPa
Poisson ratio 0.152
Vickers hardness 167 MPa
CAS registry number 7440-53-1

 

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