68Er167.26
Erbium (Er)
Element 68 · Lanthanide
Erbium (Er) is a chemical element with atomic number 68. It is classified as a lanthanide in period 6 of the periodic table (the f-block). Its standard atomic weight is 167.26 u and its ground-state electron configuration is [Xe] 4f¹² 6s².
Erbium facts
| Atomic number (Z) | 68 |
|---|---|
| Symbol | Er |
| Standard atomic weight | 167.26 u |
| Category | Lanthanide |
| Group | — (f-block) |
| Period | 6 |
| Block | f-block |
| Electron configuration | [Xe] 4f¹² 6s² |
| Electronegativity (Pauling) | 1.24 |
| State at 20 °C | Solid |
| Protons / electrons | 68 / 68 |
| Neutrons (most common isotope, approx.) | 99 |
| Molar mass | 167.26 g/mol |