71Lu174.97
Lutetium (Lu)
Element 71 · Lanthanide
Lutetium (Lu) is a chemical element with atomic number 71. It is classified as a lanthanide in period 6 of the periodic table (the f-block). Its standard atomic weight is 174.97 u and its ground-state electron configuration is [Xe] 4f¹⁴ 5d¹ 6s².
Lutetium facts
| Atomic number (Z) | 71 |
|---|---|
| Symbol | Lu |
| Standard atomic weight | 174.97 u |
| Category | Lanthanide |
| Group | — (f-block) |
| Period | 6 |
| Block | f-block |
| Electron configuration | [Xe] 4f¹⁴ 5d¹ 6s² |
| Electronegativity (Pauling) | 1.27 |
| State at 20 °C | Solid |
| Protons / electrons | 71 / 71 |
| Neutrons (most common isotope, approx.) | 104 |
| Molar mass | 174.97 g/mol |