All practice pages/Interatomic theory/Elements
Element 71, a lanthanide
The last and densest of the lanthanides, named after Paris, and now a targeted cancer treatment.
Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.
Lutetium has 71 electrons, one for every proton, so the atom carries no charge. Below are the same 71 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹ 6s²
Short form: [Xe] 4f¹⁴ 5d¹ 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 4f¹⁴ 5d¹, 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 4f¹⁴, and 2 + 6 + 10 + 14 is 32.
Lutetium sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones lutetium 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 Lu³⁺ ion in most of its compounds.
One of the rarest and most expensive rare earths, recovered from monazite and xenotime.
Georges Urbain in Paris, Carl Auer von Welsbach in Austria and Charles James in the United States each separated it from ytterbia around 1907. Urbain published first and named it after Lutetia, the Roman name for Paris.
Lutetium-177 is attached to molecules that seek out certain prostate and neuroendocrine cancers and destroys them with radiation from inside. Lutetium crystals detect gamma rays in PET scanners, lutetium catalysts help refine oil, and the slow decay of lutetium-176 dates meteorites and ancient rocks.