Lutetium is a chemical element with symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry, but not in moist air. It is considered the first element of the 6th-period transition metals and the last element in the lanthanide series, and is traditionally counted among the rare earths.
Three reasons Lutetium stands out
- 1
Used in PET scans.
- 2
Its radioactive isotope is used in targeted therapy that delivers radiation directly to cancer cells while sparing healthy tissue.
- 3
It is the densest and hardest of all the lanthanide elements.
The dense finale of the lanthanides
Lutetium is the heaviest, hardest, and densest lanthanide. Crystals containing lutetium detect gamma rays in PET scanners, while radioactive lutetium-177 carries therapeutic radiation to selected tumors. Its position at the series boundary has prompted long-running debates about periodic-table layout.