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EuEu at. wt. 151.96 at. no. 63 m.p. 822 ±5°C b.p. 1597°C sp. gr. 5.253 (25°C) valence 2 or 3.
| SHELL | K | L | M | N | O | P | Q |
| SUB SHELL | He | Neon | Argon | Krypton | Xenon | Radon | Eka-radon |
| 1s | 2s 2p | 3s 3p | 3d 4s 4p | 4d 5s 5p | 4f 5d 6s 6p | 5f 6d 7s 7p | |
| Europium | 1s22s22p63s23p63d104s24p64d105s25p64f65d16s2 | ||||||
| Symbol | 8H½ | ||||||
Europium's discovery is generally credited to Demarcay, who separated the earth in reasonably pure form in 1901. In 1890 Boisbaudran obtained basic fractions from samarium-gadolinium concentrates which had spark spectral lines not accounted for by samarium or gadolinium. These lines subsequently have been shown to belong to europium. The pure metat was not isolated until recent years. Europium is now prepared by mixing Eu203 with a 10% excess of lanthanum metal and heating the mixture in a tantalum crucible under high vacuum. The element is collected as a silvery-white metallic deposit on the walls of the crucible. As with other rare-earth metals, except for lanthanum, europium ignites in air at about 150° to 180°C. Europium is about as hard as lead and is quite ductile. It is the most reactive of the rare-earth metals, quickly oxid~ng in air. It resembles calcium in its reaction with water. Bastriasite and monazite are the principal ores containing europium. Europium has been identified spectroscopically in the sun and certain stars. Twenty-one isotopes are now recognized. Europium isotopes are good neutron absorbers and are being studied for use in nuclear control applications. Europium oxide is now widely nse4 as a phosphoractivator, and europium activated yttrium vanadate is in commercial use as the red phosphor in color TV tubes. Europium-doped plastic has been used as a laser material. With the develop ment of ion-exchange techniques and special processes, the cost of the metal has been greatly reduced in recent years. Europium is one of the rarest and most costly of the rareearth metals. It is priced at about $11 to 115/gm., or $4000/lb.
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