| Symbol | Eu |
| Atomic number | 63 |
| Group | - |
| Period | 6 |
| Block | f |
| Classification | Lanthanide |
| Appearance | - |
| Color | Silver |
| Number of protons | 63 p+ |
| Number of neutrons | 89 n0 |
| Number of electrons | 63 e- |
| Phase at STP | Solid |
| Density | 5.264 g/cm3 |
| Atomic weight | 151.964 u |
| Melting point | 1099 K 825.85 °C 1518.53 °F |
| Boiling point | 1802 K 1528.85 °C 2783.93 °F |
| Heat of vaporization | 175.73 kJ/mol |
| Electronegativity (Pauling Scale) | 1.2 |
| Electron affinity | 11.2 kJ/mol |
| Oxidation states | 0, +2, +3 (a mildly basic oxide) |
| Ionization energies |
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| Discovery | Eugène-Anatole Demarçay (1896) |
| First isolation | Eugène-Anatole Demarçay (1901) |
Discovery of europium Although europium is present in most of the minerals containing the other rare elements, due to the difficulties in separating the elements it was not until the late 1800s that the element was isolated. William Crookes observed the phosphorescent spectra of the rare elements including those eventually assigned to europium. Europium was first found in 1892 by Paul Émile Lecoq de Boisbaudran, who obtained basic fractions 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-Anatole Demarçay, who suspected samples of the recently discovered element samarium were contaminated with an unknown element in 1896 and who was able to isolate it in 1901; he then named it europium. | |