Europium

Europium
General Info
Atomic Symbol	Atomic symbol::Eu
Atomic Number	Atomic number::63
Atomic Weight	Atomic weight::152.0 g/mol
Chemical series	Lanthanide
Appearance	Silvery-white
Group, Period, Block	n/a, 6, f
Electron configuration	[Xe] 6s2, 4f7
Electrons per shell	2, 8, 18, 25, 8, 2
CAS number	CAS number::7440-53-1
Physical properties
Phase	Solid
Density	Density::5.24 g/ml
Melting point	Melting point::826°C
Boiling point	Boiling point::1527°C
Isotopes of Europium
iso NA half-life DT DE (MeV) DP 15Eu syn 36.9 y ε 2.261 150Sm 151Eu 47.8% 5x1018 y α - 147Pm 152Eu syn 13.516 y ε 1.874 152Sm 152Eu syn 13.516 y β− 1.819 152Gd 153Eu 52.2% 153Eu is stable with 90 neutrons.
All properties are for STP unless otherwise stated.

Europium, element number 63 on the periodic table, is a member of the lanthanide series of elements. The element has moderate ductility and has about the same hardness as the element lead(82). Europium got its name from the continent Europe. Europium was first discovered by the French chemist, Eugène-Antole Demarçay. When Demarcay first discovered the element he did not gather enough evidence to prove to other chemist the validity of his claims. After a few years, however, he was able to get evidence of the new element. The discovery of Europium is credited to Demarcay in the year, 1901. Europium has two common oxidation states it uses, +2 and +3. Europium reacts quickly with water and with air. When it reacts with water, Europium has a similar raction to that of calcium and water.

Properties

Physical Properties

Europium is a solid and has a silvery white appearance. Europium is rarely seen in its silvery white state because it is usually in its oxidized state, and when it oxidizes it has a discoloration. Europium has good ductility, meaning it will withstand some pressure before it fractures and breaks. Of all the elements in the lanthanide series, Europium has the lowest density (5.24 g/ml) and has the second lowest melting point(826°C).

Chemical Properties

Europium oxidizes quickly and no longer has its silvery white appearance when oxidized.

Europium is the most reactive of all the rare earth metals. This element reacts explosively in water, similar to calcium. Europium ignites with air when temperatures reach that of about 150-180°C. When Europium reacts with water (H₂O) they combine to make europium hydroxide. Euopium reacts faster when exposed to hot water; slower when exposed to cold water. Europium also reacts with air forming europium (III) oxide. Europium also reacts with the halogens and acids forming compunds such as europium(III) chloride. A unique feature of Europium, compared to the characteristics of the other rare-earth metals, is that Europium forms stable compounds in two states (Eu²⁺ and Eu³⁺) whereas other elements included in the rare-earth metals usually form stable compounds in only one state.

Occurrences

A sample of monazite, an ore in which Europium can be extracted.

Europium is a rare earth metal meaning it is not found very often in or on the earth. Europium is not found alone in nature, but is most commonly found in ores such as monazite, bastnasite, and gadolinite, and is commonly found in other ores such as xenotime and loparite. Europium usually consist of no more than 0.2% of the ore it is found in. Europium is one of the least abundant elements included in the rare earth metals. Through studies of the light given off from the sun and other stars, there has been indication that Europium can be found on these stars. Europium's abundance in the earth's crust is 0.00018%, which is a very small amount. Europium's abundance on the sun is 5×10^-8%, an even smaller percentage than that of the amount of Europium in the earth's crust. Both of these percentages demonstrate how little Europium exists naturally in the universe. Europium can be created during nuclear fission of uranium-235. Uranium usually splits into two large fragments and can sometimes form a Europium isotope. Europium-155 is formed most often in this way, but Europium-152 and Europium-154 can form in this way as well. Europium-155 is formed about 0.03% of the time during fission, which means that if there were 10,000 fissions, only 3 would produce europium-155 atoms.

Uses

Europium is the most expensive of all the rare earth metals. This is due to the cost of extracting the element from the ore containing it, and concentrating it from the ore. Europium has been used on bank notes to ensure the validity of the note, protecting it from being counterfeited. Europium has also been used in screens such as a television and a computer monitor. It produces the red color that is appears on the screen. Europium also is used in the control rods of nuclear reactors, this is the elements main use since it is such an expensive metal. Europium will absorb neutrons very easily, which helps control the nuclear reactions. This element is mostly used in Russia and the Ukraine to absorb neutrons from uranium fission reactions. The naturally occurring isotopes of europium (europium-151 and europium-153) are not radioactive, however, the europium atoms created by nuclear fission (europium-152,europium-154, and europium-155) are radioactive.

Effect on Humans

Europium is not an abundant element, so humans do not come in contact with it everyday. However, when humans do come in contact with Europium, the element can be hazardous to their health. Europium can be explosive and also can present a fire hazard. Europium's explosiveness causes people to take great care when handling the element. Because the element reacts very quickly with water and oxygen in the air, it is strongly advised to take great care when handling the element. Europium can enter the body by breathing, eating, or drinking. Only about 0.05% of the Europium ingested actually enters the bloodstream. Of this small percentage of Europium that enters the bloodstream, 40% stays in the liver, another 40% gets on the surface of bones, 6% is left in the liver, and the rest of the europium that was entered into the bloodstream is excreted. the isotopes europium-152 and europium-154 can give off gamma radiation and beta particles which can be harmful to humans. The gamma and beta particles can increase the likelihood of getting cancer in the liver and in bones, this is the main health risk.