Atomic number 95
Americium
Actinide
No photo: here’s why
Americium is synthetic and radioactive - yet a microscopic sealed speck sits inside almost every smoke detector, quietly watching for smoke. You still never see the bare metal.
Quick facts
- Atomic mass
- 243.00
- Group
- –
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 1.13
- Common ox. states
- +3, +4, +5, +6
Properties
[Rn] 5f⁷ 7s²
- Ionization energy
- 578.0 kJ/mol
- Electron affinity
- –
- Melting point
- 1449.00 K (1175.8 °C)
- Boiling point
- 2284.00 K (2010.8 °C)
How dangerous is it?
A tiny, sealed speck of this man made metal sits inside many smoke detectors, where the amount is so small and so shielded it is safe in the home.
- RadioactiveImmediate and cumulative
It gives off alpha radiation that is easily blocked by a thin barrier but dangerous to cells if the sealed source is broken open and the material gets inside. (the smoke detector amount is minute and sealed; the risk is only from loose, unshielded material)
Used only as sealed sources, and larger amounts are handled in gloveboxes by licensed labs.
How it bonds· family overview
Americium (Am) is an actinide. Like the lanthanides it tends toward a +3 oxidation state, but the early actinides (Th–Am) routinely access +4, +5, +6, even +7 because the 5f electrons are easier to ionize. Most actinides are radioactive; their "bonding" in school is read off the periodic table, not measured in lab.
