Europium is a chemical element with the symbol Eu and atomic number 63. Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. Europium usually assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on Earth.
63EuEuropium
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Atomic properties
| Standard atomic weight | 151.964 ±0.001 |
|---|---|
| Atomic mass | 151.964 u |
Atomic radii
| Radius (empirical) | 180 pm |
|---|---|
| Radius (calculated) | 231 pm |
| Covalent radius | 198 ±6 pm |
Atomic shell
| Electron configuration | Xe 4f7 6s2 |
|---|---|
| Ionization energy | (1st) 5.670385 eV (2nd) 11.24 eV (3rd) 24.84 eV (4th) 42.94 eV (5th) 63.2 eV |
| Shell model | Electrons k-shell:2 l-shell:8 m-shell:18 n-shell:25 o-shell:8 p-shell:2 |
Physical properties
| Phase | solid |
|---|---|
| Density | 5.245 g·cm−3 (298.1 K) |
| Molar volume | 2.897·10-5 m3·mol−1 |
Temperatures
| Melting point | 1,099 K |
|---|---|
| Boiling point | 1,802 K |
| Liquid range | 703 K |
Enthalpies
| Melting enthalpy | 9.2 kJ·mol-1 |
|---|---|
| Enthalpy of vaporization | 175 kJ·mol-1 |
| Binding energy | 175 kJ·mol-1 |
Heat and conductivity
| Thermal conductivity | 14 W·m-1·K-1 |
|---|---|
| Expansion coefficient | 3.5·10-5 K-1 |
Hardnesses
| Vickers hardness | 167 NM·m-2 |
|---|
Elastic properties
| Young’s modulus | 18 GPa |
|---|---|
| Shear modulus | 7.8 GPa |
| Bulk modulus | 8.3 GPa |
| Poisson’s ratio | 0.15 |
Electrical properties
| Electrical conductivity | 1.11·106 S·m-1 |
|---|---|
| Resistance | 9·10-7 Ωm |
Magnetism
| Magnetism | paramagnetic |
|---|---|
| Magnetic susceptibility | 0.034 cm3·mol−1 |
Chemical properties
| Basicity | slightly basic |
|---|---|
| Oxidation state | 2, 3 |
| Standard potential | -1.99 V (Eu3+ + 3e- → Eu) |
Electronegativity
| Allred-Rochow scale | 1.01 |
|---|---|
| Nagle scale | 1.06 |
Other properties
| Natural occurrence | primordial |
|---|---|
| Crystal structure | Body-centered cubic |
| Goldschmidt Classification | lithophile |
| Superconductor | without transition tempperature |
| Price/kg | 31.4 USD |
Natural abundances
satellite_alt
Universe
0.5 ppb ≈ 5.02·109 M☉
sunny
Sun
0.5 ppb ≈ 9.94·108 Mt
destruction
Meteorite
60 ppb ≈ 60 mg
public
Earth’s crust
1,800 ppb ≈ 49,800 Mt
water_drop
Oceans
1.3·10-4 ppb ≈ 178 t
waves
Flowing water
0.007 ppb ≈ 112 t
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