Element record / Actinide
Americium
MetalPrimarily synthetic supply- Atomic number
- 95
- Atomic mass (u)
- 243.061380
- Category
- Actinide
- Standard state
- Solid
- Melting point
- 1175.85 °C (1449 K)
- Boiling point
- 2010.85 °C (2284 K)
- Density (g/cm³)
- 13.69
- Electronegativity (Pauling)
- 1.3
- Electron configuration
- [Rn]7s2 5f7
- Oxidation states
- +6, +5, +4, +3
- Atomic radius (pm)
- 244
- First ionization energy (eV)
- 5.993
Discovery & recognition
- Discovery year / period (PubChem)
- 1944
- Discovery credited to (RSC)
- Glenn Seaborg and colleagues
- Date or period recorded by RSC
- 1944
- Discovery place
- Chicago, Illinois, United States
An ancient date does not identify a first human discovery. Different references may date observation, isolation and formal recognition differently.
Natural occurrence & production
This transuranium element is primarily produced through nuclear reactions in reactors or particle accelerators. Some transuranium elements also occur naturally in extremely small traces; that is different from a mineable deposit.
“Americium occurs naturally in uranium minerals, but only in trace amounts.”
Royal Society of Chemistry · occurrence excerpt ↗
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PubChem · properties and references ↗
Royal Society of Chemistry · occurrence, uses and discovery history ↗
Reference values are not product specifications. Blank values have not been estimated. For superheavy elements, some properties and family assignments are theoretical or incompletely measured.