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Praseodymium (Pr)

QUICK REFERENCE

  • Symbol: Pr
  • Atomic Number: 59
  • Atomic Weight: 140.90766
  • Element Classification: Lanthanide
  • Discovered By: Carl Auer von Welsbach
  • Discovery Date: 1885
  • Name Origin: Greek: ‘prasios didymos’ (green twin), for its green salts
  • Density(g/cc): 6.773
  • Melting Point: 931°C
  • Boiling Point: 3520°C
  • Appearance: Silvery, soft, malleable, and ductile metal
  • Atomic Radius(pm): 182

Discovery

Praseodymium was discovered by Austrian chemist Carl Auer von Welsbach in 1885. Von Welsbach separated praseodymium, along with neodymium, from a substance called didymium through fractional crystallization of their double ammonium nitrate salts. His work corrected the misconception that didymium was a single element, revealing it instead to be a mixture of two elements with similar properties. Praseodymium was named for the green color of its salts, from the Greek words ‘prasios’, meaning green, and ‘didymos’, meaning twin.

Relation to Other Elements

Praseodymium is a member of the lanthanide series, a group of fifteen chemically similar elements from lanthanum to lutetium, plus scandium and yttrium. These elements are characterized by their variable electronic configurations, which contribute to their complex chemistry and magnetic properties. Praseodymium has a single stable oxidation state of +3 in most of its compounds, similar to other lanthanides, but it can also exhibit a +4 state under certain conditions.

Natural Occurrence

Praseodymium is never found in nature as a free element but is quite abundant in the Earth’s crust for a rare earth metal, occurring in minerals such as monazite and bastnasite. These minerals contain a mixture of lanthanides, including praseodymium, and are the primary sources of rare earth elements. Praseodymium is extracted through a complex series of metallurgical processes involving solvent extraction and ion exchange techniques.

Uses

Praseodymium has a range of applications that take advantage of its unique properties:

  • Alloys: Praseodymium is used in alloys for aircraft engines and to make high-strength metals used in motors and turbines.
  • Magnets: Along with neodymium, praseodymium is used to create strong permanent magnets known as neodymium-iron-boron (NdFeB) magnets. These magnets are essential for wind turbines, hard disk drives, and electric vehicle motors.
  • Glass and Ceramics: Praseodymium oxide is used to color glasses and enamels, including yellow glass for protective goggles that filter out UV and infrared radiation.
  • Catalysts: It serves as a catalyst in carbon-arc lighting, especially in the motion picture industry, and in the catalytic cracking of petroleum.
  • Others: Praseodymium is used in the making of specialized optical fibers and in various applications requiring its luminescent properties.

The discovery of praseodymium marked an important development in the study of rare earth elements, contributing to the technological advances in materials science, electronics, and green energy solutions. Its applications demonstrate the critical role of lanthanides in modern technology and industry.

Cerium (Ce)

Neodymium (Nd)