Lutetium (symbol Lu, atomic number 71) is the heaviest and hardest rare-earth metal, used in PET-scan detectors. It is classified as a lanthanide and sits in the lanthanide series (f-block), period 6 of the periodic table.
Overview
Lutetium is the chemical element with atomic number 71 and the symbol Lu. With a standard atomic weight of 174.97, it is a lanthanide. In the periodic table it occupies the lanthanide series (f-block) and period 6, and under standard conditions it is normally a solid. Lutetium is the heaviest and hardest rare-earth metal, used in PET-scan detectors.
Atomic structure
An atom of Lutetium has 71 protons in its nucleus and, when neutral, 71 electrons arranged in the configuration [Xe] 4f14 5d1 6s2. Its standard atomic weight of 174.97 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Lutetium was discovered in 1907 by Georges Urbain, Carl Auer von Welsbach. It follows Ytterbium (Yb) and precedes Hafnium (Hf) in order of atomic number.
| Atomic number | 71 |
|---|---|
| Symbol | Lu |
| Atomic mass | 174.97 |
| Category | Lanthanide |
| Group | — |
| Period | 6 |
| Electron configuration | [Xe] 4f14 5d1 6s2 |
| Phase at STP | Solid |
| Discovered | 1907 (Georges Urbain, Carl Auer von Welsbach) |