Am
Americium
AMERICIUM
TRANSITION ELEMENT: ACTINIDE
| Atomic number: | 95 |
| Group numbers: | 3 |
| Period: | 7 |
| Electronic configuration: | [Rn] 5f7 7s2 |
| Formal oxidation number: | +3 +4 +5 +6 |
| Electronegativities: | - |
| Atomic radius / pm: | 173 |
| Relative atomic mass: | - |
Americium was discovered by Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, and Albert Ghiorso (US) in 1944. Named for the American continent. It is a silvery-white, artificially produced radioactive metal. Americium was produced by bombarding plutonium with neutrons. Americium-241 is currently used in smoke detectors.
| Density / g dm-3: | 13670 | (293 K) |
| Molar volume / cm3mol-1: | 17.78 | (293 K) |
| Electrical resistivity / µΩcm: | 68 | (20 °C) |
| Thermal conductivity / W m-1K-1: | 10 |
| Melting point / °C: | 1176 |
| Boiling point / °C: | 2011 |
| Heat of fusion / kJ mol-1: | 14.4 |
| Heat of vaporization / kJ mol-1: | 238.5 |
| Heat of atomization / kJ mol-1: | 266 |
| First ionization energy / kJ mol-1: | 576.39 |
| Second ionization energy / kJ mol-1: | - |
| Third ionization energy / kJ mol-1: | - |
| in the atmosphere / ppm: | - |
| in the Earth's crust / ppm: | - |
| in the oceans / ppm: | - |
| Crystal structure: | hexagonal |
| Unit-cell dimensions / pm: | a=346.80, c=1124.0 |
| Space group: | P63/mmc |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 241Am | 241.056 83(2) | * |
| 243Am | 243.061 38(2) | * |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| 94 Plutonium | ← | 95 Americium | → | 96 Curium |
Citing this page:
Generalic, Eni. "Americium." EniG. Periodic Table of the Elements. KTF-Split, 13 Feb. 2025. Web. {Date of access}. <https://www.periodni.com/am.html>.
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