Element 95
Americium (Am)
Americium (Am) is element 95 of the periodic table, a actinide in period 7 (f-block) with an atomic mass of 243 and is a solid at standard conditions.
At a glance
- Atomic number
- 95
- Symbol
- Am
- Atomic mass
- 243 u
- Category
- Actinides
- Period
- 7
- Block
- f-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f7 7s2
- Shorthand configuration
- [Rn] 5f7 7s2
- Electrons per shell
- 2, 8, 18, 32, 25, 8, 2
- Oxidation states
- +2, +3, +4, +5, +6, +7
Physical properties
- Melting point
- 1449 K
- Boiling point
- 2880 K
- Density
- 13.69 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.3
- Atomic radius
- 173 pm
- Covalent radius
- 180 pm
- First ionization energy
- 578 kJ/mol
- Electron affinity
- 10 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Am-243 | 243.06138 | — | Half-life 7370 years |
Common uses
- Smoke detectors
- Neutron sources
- Space missions
Discovery
- Year
- 1944
- Discovered by
- Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso
- Country
- USA