What element has the symbol 'Lu'?

The story behind the answer

Lu is Lutetium, element 71. Lithium is Li; Lead uses its Latin name plumbum, symbol Pb; and “Lutetronic” isn’t an element. So only Lutetium matches Lu.

Lutetium is the last lanthanide (“ultimate” rare earth), a dense, silvery metal named after Lutetia, the ancient Roman name for Paris. That Paris link shows up in memory and tech: lutetium-based crystals (LSO) are used in PET scanners as fast scintillators, and Lu compounds serve as catalysts in refining and polymerization. Memory tip: think “Lu = Louvre in Paris” → Lutetium from Lutetia; or “Lu is the last lanthanide”—U for “ultimate.”