Americium (Am)
Americium (Am) is element 95 of the periodic table, an actinide in period 7, in the f-block. It has no stable isotope and no standard atomic weight; 243 is the mass number of its longest-lived isotope. At room temperature it is a solid; it melts at 1175.85 °C and boils at 2010.85 °C.
| Atomic number | 95 |
|---|---|
| Symbol | Am |
| Standard atomic weight | [243] (mass number of the longest-lived isotope) |
| Molar mass | [243] g/mol |
| Category | Actinide |
| Group | f-block (actinide series) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 7s2 5f7 |
| Oxidation states | +6, +5, +4, +3 |
| Electronegativity (Pauling) | 1.3 |
| Atomic radius (van der Waals) | 244 pm |
| First ionisation energy | 5.993 eV (578.2 kJ/mol) |
| Electron affinity | — |
| State at room temperature | Solid |
| Melting point | 1449 K (1175.85 °C) |
| Boiling point | 2284 K (2010.85 °C) |
| Density | 13.69 g/cm³ |
| Discovered | 1944 |
Actinides
Ac · ActiniumTh · ThoriumPa · ProtactiniumU · UraniumNp · NeptuniumPu · PlutoniumCm · CuriumBk · BerkeliumCf · CaliforniumEs · EinsteiniumFm · FermiumMd · MendeleviumNo · Nobelium
Calculate with Americium
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.