Praseodymium Facts - Element 59

Praseodymium Facts - Element 59 Praseodymium is element 59 on the periodic table with the element symbol Pr. Its one of the rare earth metals or lanthanides. Here is a collection of interesting facts about praseodymium, including its history, properties, uses, and sources. Praseodymium was discovered by Swedish chemist Carl Mosander in 1841, but he did not purify it. He was working on rare earth samples, which contain elements with such similar properties they are extremely hard to separate from each other. From a crude cerium nitrate sample, he isolated an oxide he called lantana, which was lanthanum oxide. Lantana turned out to be a mixture of oxides. One fraction was a pink fraction he called didymium. Per Teodor Cleve (1874) and Lecoq de Boisbaudran (1879) determined didymium was a mixture of elements. In 1885, Austrian chemist Carl von Welsbach separated didymium into praseodymium and neodymium. Credit for the official discovery and isolation of element 59 is generally given to von Welsbach.Praseodymium gets it name from the Greek words prasios, which means green, and didymos, which means twin. The twin part refers to the element being the twin of neodymium in didymium, while green refers to the color of the salt isolated by von Welsbach. Praseody mium forms Pr(III) cations, which are yellowish green in water and glass. In addition to the 3 oxidation state, Pr also occurs in 2, 4, and (unique for a lanthanide) 5. Only the 3 state occurs in aqueous solutions.Praseodymium is a soft silver-colored metal that develops a green oxide coating in air. This coating peels or spalls off, exposing fresh metal to oxidation. To prevent degradation, pure praseodymium is typically stored under a protective atmosphere or in oil.Element 59 is highly malleable and ductile. Praseodymium is unusual in that it is paramagnetic at all temperatures above 1 K. Other rare earth metals are ferromagnetic or antiferromagnetic at low temperatures.Natural praseodymium consists of one stable isotope, praseodymium-141. 38 radioisotopes are known, the most stable being Pr-143, which has a half-life of 13.57 days. Praseodymium isotopes range from mass number 121 to 159. 15 nuclear isomers are also known.Praseodymium occurs naturally in the Earths crust at an abundance of 9.5 parts per million. It accounts for about 5% of the lanthanid es found in the minerals monazite and bastnasite. Seawater contains 1 part per trillion of Pr. Essentially no praseodymium is found in the Earths atmosphere. The rare earth elements have many uses in modern society and are considered extremely valuable. Pr gives a yellow color to glass and enamel. Around 5% of mischmetal consists of praseodymium. The element is used with other rare earths to make carbon arc lights. It colors cubic zirconia yellow-green and may be added to simulated gemstones to mimic peridot. Modern firesteel contains about 4% praseodymium. Didymium, which contains Pr, is used to make glass for protective eyewear for welders and glass blowers. Pr is alloyed with other metals to made powerful rare earth magnets, high strength metals, and magnetocaloric materials. Element 59 is used as a doping agent to make fiber optic amplifiers and to slow light pulses. Praseodymium oxide is an important oxidation catalyst.Praseodymium serves no known biological function. Like other rare earth elements, Pr exhibits low to moderate toxicity to organisms. Praseodymium Element Data Element Name: Praseodymium Element Symbol: Pr Atomic Number: 59 Element Group: f-block element, lanthanide or rare earth Element Period: period 6 Atomic Weight:  140.90766(2) Discovery: Carl Auer von Welsbach (1885) Electron Configuration: [Xe] 4f3  6s2 Melting Point:  1208  K  Ã¢â‚¬â€¹(935  Ã‚ °C, ​1715  Ã‚ °F) Boiling Point:  3403  K ​(3130  Ã‚ °C, ​5666  Ã‚ °F) Density:  6.77  g/cm3 (near room temperature) Phase: solid Heat of Fusion: 6.89 kJ/mol Heat of Vaporization:  331  kJ/mol Molar Heat Capacity:  27.20  J/(mol ·K) Magnetic Ordering: paramagnetic Oxidation States:  5, 4,  3, 2 Electronegativity:  Pauling  scale: 1.13 Ionization Energies: 1st:  527  kJ/mol2nd:  1020  kJ/mol3rd:  2086  kJ/mol Atomic Radius: 182 picometers Crystal Structure: double hexagonal close-packed or DHCP References Weast, Robert (1984).  CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp.  E110.Emsley, John (2011). Natures Building Blocks: An A-Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-960563-7.Gschneidner, K.A., and Eyring, L., Handbook on the Physics and Chemistry of Rare Earths, North Holland Publishing Co., Amsterdam, 1978.Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.R. J. Callow,  The Industrial Chemistry of the Lanthanons, Yttrium, Thorium and Uranium, Pergamon Press, 1967.