Einsteinium (Es)
Einsteinium (Es) is element 99, an actinide. Atomic mass 252, configuration [Rn] 5f¹¹ 7s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 99 |
|---|---|
| Symbol | Es |
| Standard atomic weight | 252 |
| Category | Actinide |
| Period | 7 |
| State at room temperature | Solid |
| Electron configuration | [Rn] 5f¹¹ 7s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +3 |
| Common ions | No common ions |
| First ionization energy | 619 kJ/mol |
| Melting point | 860°C |
Common uses
- Research only
Where it matters
- Cold War Science (Discovered in "Ivy Mike" H-bomb debris)
Hazards
- Highly radioactive
History
| Discovered | 1952 |
|---|---|
| Discovered by | Albert Ghiorso et al. |
| Name | Albert Einstein |