Einsteinium (Es)
Einsteinium (Es) is element 99 of the periodic table, an actinide in period 7, in the f-block. It has no stable isotope and no standard atomic weight; 252 is the mass number of its longest-lived isotope. At room temperature it is a solid.
| Atomic number | 99 |
|---|---|
| Symbol | Es |
| Standard atomic weight | [252] (mass number of the longest-lived isotope) |
| Molar mass | [252] g/mol |
| Category | Actinide |
| Group | f-block (actinide series) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 7s2 5f11 |
| Oxidation states | +3 |
| Electronegativity (Pauling) | 1.3 |
| Atomic radius (van der Waals) | 245 pm |
| First ionisation energy | 6.42 eV (619.4 kJ/mol) |
| Electron affinity | — |
| State at room temperature | Solid |
| Melting point | 1133 K (859.85 °C) |
| Boiling point | — |
| Density | — |
| Discovered | 1952 |
Actinides
Ac · ActiniumTh · ThoriumPa · ProtactiniumU · UraniumNp · NeptuniumPu · PlutoniumAm · AmericiumCm · CuriumBk · BerkeliumCf · CaliforniumFm · FermiumMd · MendeleviumNo · Nobelium
Calculate with Einsteinium
Atomic weight: IUPAC CIAAW — no standard atomic weight; mass number in brackets. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.