Einsteinium
Einsteinium (锿, symbol Es) is chemical element number 99, an Actinide in period 7 of the periodic table, with a standard atomic weight of about 252. Synthetic element discovered in the fallout of the first hydrogen bomb test.
Properties
| Atomic number | 99 |
|---|---|
| Symbol | Es |
| Atomic mass | 252 u |
| Category | Actinide |
| Period | 7 |
| Group | — |
| Electron configuration | [Rn] 5f¹¹ 7s² |
| Electronegativity | 1.3 |
| Covalent radius | — |
| Density | 8.84 g/cm³ |
| Melting point | 1133 K |
| Boiling point | 1269 K |
| Discovery | Ghiorso et al., 1952 |
Overview
Synthetic element discovered in the fallout of the first hydrogen bomb test. Einsteinium (Es) holds position 99 in the periodic table, an Actinide in period 7. As an actinide it is typically radioactive and closely tied to nuclear technology.
It has the configuration [Rn] 5f¹¹ 7s² and an electronegativity near 1.3; its 2 outer-shell electrons drive its bonding. Under standard conditions it exists as a solid; it melts near 1133 K (859.9 °C), boils near 1269 K (995.9 °C), has a density around 8.84 g/cm³.
It is widely used in Research. On the safety side, it carries a high hazard rating. It was first described by Ghiorso et al. in 1952. The periodic trends guide explains the underlying patterns.
Electron shells
Electrons per shell: 2 · 8 · 18 · 32 · 29 · 8 · 2
Main uses
- Research
Hazard
Compounds containing Einsteinium
No compounds in this knowledge base contain Einsteinium yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.