Element Einsteinium
Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein.
Its most common isotope einsteinium-253 (half-life 20.47 days) is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year.
Einsteinium is a synthetic element with the symbol Es and atomic number 99. As a member of the actinide series, it is the seventh transuranic element.
Names and Identifiers
| Chemical Formula: | Es |
| CAS: | 7429-92-7 |
| Molecular Weight: | 252.08000g/mol |
| EC Number : | n/a |
| MDL Number: | n/a |
| Color: | unknown (presumably metallic/ silvery white/ gray) |
| Other Names: | Einstenio, Einstânio |
| PubChem CID: | 23913 |
| IUPAC Name: | Einsteinium |
| Inchl: | InChI=1S/Es |
| InChI Key: | CKBRQZNRCSJHFT-UHFFFAOYSA-N |
| Canonical SMILES: | [Es] |
| ICSC Number: | n/a |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 8.84 g/cm³ |
| Boiling Point: | 1269 K (996 °C, 1825 °F) |
| Melting Point: | 1133 K (860 °C, 1580 °F) |
| Molecular Formula: | Es |
| Flash Point: | n/a |
| Exact Mass: | 252.08300 |
Eighteen nuclides and three nuclear isomers are known for einsteinium, with atomic weights ranging from 240 to 257.
All are radioactive and the most stable nuclide, 252Es, has a half-life of 471.7 days.
The next most stable isotopes are 254Es (half-life 275.7 days), 255Es (39.8 days), and 253Es (20.47 days).
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 249Es | 249.07640 | 1.70 h | EC to 249Cf; α to 245Bk | 7/2 | |
| 250Es | 250.0787 | 8.6 h | EC to 250Cf; α to 246Bk | 6 | |
| 251Es | 251.07998 | 1.38 d | EC to 251Cf; α to 247Bk | 3/2 | |
| 252Es | 252.082944 (23) | 1.29 y | EC to 252Cf; α to 248Bk; β– to 252Fm | 5 | |
| 253Es | 253.08482 | 20.47 d | α to 249Bk; SF | 7/2 | 4.10 |
| 254Es | 254.08802 | 276 d | EC to 254Cf; α to 250Bk; β– to 254Fm; SF | 7 | |
| 255Es | 255.09027 | 40 d | α to 251Bk; β– to 255Fm; SF | 7/2 |