Europium is a metal about as hard as lead and is quite ductile. It becomes a superconductor when it is simultaneously at both high pressure (80 GPa) and at low temperature (1.8 K). The occurrence of superconductivity is due to the applied pressure driving europium from a divalent (J = 7/2) state into a trivalent (J = 0) state. In the divalent state, the strong local magnetic moment is thought to play a role in suppressing the superconductivity and so through eliminating this local moment the opportunity for superconductivity arises.
Europium is the most reactive of the rare earth elements; it rapidly oxidizes in air (bulk oxidation of a centimeter-sized sample occurs within several days) and resembles calcium in its reaction with water. Samples 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 150 °C to 180 °C to form europium(III) oxide:
Europium(II) compounds tend to predominate, in contrast to most lanthanides which generally form compounds with an oxidation state of +3. Europium(II) chemistry is very similar to barium(II) chemistry, as they have similar ionic radii. Divalent europium is a mild reducing agent, such that under atmospheric conditions, it is the trivalent form that predominates. Under anaerobic, and particularly under geothermal conditions, the divalent form is sufficiently stable such that it tends to be incorporated into minerals of calcium and the other alkaline earths. This is the cause of the "negative europium anomaly", that depletes europium from being incorporated into the most usual light lanthanide minerals such as monazite, relative to the chondritic abundance. Bastnäsite tends to show less of a negative europium anomaly than monazite does, and hence is the major source of europium today. The accessible divalency of europium has always made it one of the easiest lanthanides to extract and purify, even when present in low concentration, as it usually is.
The base value of each unit of ranges between 10 and 35Ð per unit, with up to 3 units being found at any one time.
Presence on Mars: Very Rare
|Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6|
|Group 4|||Actininum | Areanetium | Borane | Carbon Tetrachloride | Dubnium | Dysprosium | Erbium | Europium | Ferrous Dixenate | |Gadollinium | Golgathium | Holmium | Holmium Sulfate | Iron Golgathide | Neodymium | Praseodymium | Promethium | |Protactinium | Rutherfordium | Samarium | Selenium Arsenide | Terbium | Thallium Titanide | Thulium | Uranium||