All practice pages/Interatomic theory/Elements
Element 59, a lanthanide
The green twin, split from its sister element in 1885, now found in strong magnets and glassblowers' goggles.
Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.
Praseodymium has 59 electrons, one for every proton, so the atom carries no charge. Below are the same 59 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f³ 5s² 5p⁶ 6s²
Short form: [Xe] 4f³ 6s², where [Xe] stands for the 54 electrons xenon already has.
That list runs by shell. In the order the subshells fill it reads [Xe] 6s² 4f³, because a subshell fills by its energy, not by its shell number.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14. Shell 4 here is 4s² 4p⁶ 4d¹⁰ 4f³, and 2 + 6 + 10 + 3 is 21.
Praseodymium sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones praseodymium can lose, gain or share, so they are the ones that decide what it bonds with.
Like the other lanthanides, it gives up three electrons to form the Pr³⁺ ion in most of its compounds.
Found with the other light rare earths in bastnäsite and monazite, mostly mined in China.
In 1841 Carl Gustaf Mosander thought he had found an element he called didymium, twin. In 1885 Carl Auer von Welsbach showed it was really two elements and named them praseodymium, green twin, and neodymium, new twin.
Mixed with neodymium in powerful magnets for motors and wind turbines, alloyed with magnesium for aircraft engines, and added to glass and enamels for a yellow-green color. Didymium glass, containing praseodymium and neodymium, protects the eyes of glassblowers by filtering out the yellow glare of hot sodium.