Praseodymium

Praseodymium(III) hydroxide

Auer von Welsbach

Monazite acid cracking process

Praseodymium is a chemical element with the symbol Pr and atomic number 59. It is the third member of the lanthanide series, a group of 15 metals in the periodic table that are known for their similar properties. Praseodymium is a soft, silvery, malleable, and ductile metal in its pure form. It was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. Praseodymium is not found free in nature, but it is contained in various minerals, including monazite and bastnäsite, which are important sources of rare earth elements.

Properties

Praseodymium has several physical and chemical properties that are characteristic of the lanthanide series. It has a melting point of 931°C (1708°F) and a boiling point of 3520°C (6368°F). The element exhibits a hexagonal close-packed crystal structure at room temperature. Praseodymium is more resistant to corrosion in air than some other rare earth metals, but it still tarnishes slowly and reacts with water to form praseodymium(III) hydroxide.

Applications

Praseodymium is used in various applications due to its unique properties. One of its most significant uses is in the creation of high-strength alloys used in aircraft engines. Praseodymium is also a component in neodymium magnets, which are powerful permanent magnets made from an alloy of neodymium, iron, and boron. These magnets are used in numerous devices such as headphones, electric motors, and hard disk drives.

In addition to its use in magnets and alloys, praseodymium is used in the manufacturing of glasses and ceramics to create a yellow color. It is also used in carbon arc lights for the film industry and in the production of fiber optics and lasers.

Occurrence

Praseodymium is not a particularly abundant element, but it is not rare either. It is the 37th most abundant element in the Earth's crust. Praseodymium is usually mined from rare earth mineral deposits, with the largest concentrations found in China, the United States, Brazil, India, Sri Lanka, and Australia. The extraction and separation of praseodymium from other rare earth elements are complex processes that involve various chemical reactions and separations.

Health and Environmental Effects

Praseodymium compounds, if ingested or inhaled, can be considered moderately toxic. Like other rare earth elements, the impact of praseodymium on human health and the environment is not fully understood, but it is known that the dust and salts of praseodymium can be irritating to the skin and eyes. In the workplace, precautions are necessary to avoid exposure to praseodymium dust.

See Also

• Lanthanide series
• Rare earth element
• Carl Auer von Welsbach
• Monazite
• Bastnäsite