Name: praseodymium
Symbol: Pr
Atomic number: 59
Atomic weight: 140.90765 (2)
Group in periodic table:
Group name: Lanthanoid
Period in periodic table: 6 (lanthanoid)
Block in periodic table: f-block
CAS registry ID: 7440-10-0
Praseodymium is soft, silvery, malleable, and ductile. It was prepared in relatively pure form in 1931. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that "spalls" away when exposed to air. The metal should be stored under an inert atmosphere or under mineral oil or petroleum.
The rare-earth oxides, including Pr2O3, are among the most refractory substances known. It is a component of misch metal, used for lighter flints, and of the glass in welders' goggles.