All practice pages/Interatomic theory/Elements
Element 63, a lanthanide
The red glow of old color televisions, and part of the hidden glow that protects euro banknotes from counterfeiters.
Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.
Europium has 63 electrons, one for every proton, so the atom carries no charge. Below are the same 63 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 6s²
Short form: [Xe] 4f⁷ 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 4f⁷, 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 4f⁷, and 2 + 6 + 10 + 7 is 25.
Europium sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones europium 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 Eu³⁺ ion in most of its compounds.
One of the less common rare earths, found in bastnäsite and monazite, mostly mined in China.
Eugène-Anatole Demarçay separated it in 1901 after noticing unexplained lines in the spectra of samarium samples, and named it after Europe.
Europium phosphors glow red and blue in fluorescent lamps, LEDs and old tube televisions, whose red dots contained europium. Europium compounds that glow under ultraviolet light are used as security marks, including on euro banknotes.