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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
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General:
| Name: Americium | Symbol: Am |
| Type: Rare Earth, Actinoid, Transuranium. | Atomic weight: 243 |
| Density @ 293 K: 13.67 g/cm3 | Atomic volume: 17.78 cm3/mol |
| Discovered: 241Am was first identified in 1944 by Seaborg, James and Morgan at the metallurgical laboratory at the University of Chicago. It was produced by the beta-particle decay of plutonium-241, which had been produced in a nuclear reactor by neutron bombardment of plutonium-239. The researchers at first referred to americium as "pandemonium" owing to the difficulties they encountered trying to isolate it from another new element with which it was very closely associated, curium - or "delirium" as it was first called. Americium was first isolated as a pure compound by Cunningham in 1945. | |
States
| State (s, l, g): solid | |
| Melting point: 1449 K (1176 oC) | Boiling point: 2880 K (2607 oC) |
Energies
| Specific heat capacity: 0.11 J/gK | Heat of atomization: 266 kJ mol-1 |
| Heat of fusion: 14.40 kJ mol-1 | Heat of vaporization: 238.5 kJ mol-1 |
| 1st ionization energy: 578 kJ mol-1 | 2nd ionization energy: kJ mol-1 |
| 3rd ionization energy: kJ mol-1 | Electron affinity: kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,32,25,8,2 | Electron configuration: [Rn] 5f7 7s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 6 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 3 |
| Electronegativity (Pauling Scale): 1.3 | Polarizability volume: 23.3 Å3 |
Appearance & Characteristics
| Structure: hcp: hexagonal close-packed | Color: silvery-white |
| Uses: a source of ionization for smoke detectors and a portable source for gamma radiography. | Hardness: mohs |
| Harmful effects: strongly radioactive | |
| Characteristics: strongly radioactive alpha emitter. | |
Reactions
| Reaction with air: | Reaction with 6 M HCl: |
| Reaction with 15 M HNO3: | Reaction with 6 M NaOH: |
Compounds
| Oxide(s): AmO Am2O3 AmO2 | Chloride(s): AmCl2 AmCl3 |
| Hydride(s): AmH2 AmH3 |
Radius
| Atomic radius: 173 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 111.5 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 10 W m-1 K-1 | Electrical conductivity: mS cm-1 |
Abundance & Isotopes
| Abundance earth's crust: nil | |
| Abundance solar system: negligible | |
| Cost, pure: $ per 100g | |
| Cost, bulk: $ per 100g | |
| Source: Synthetic; neutron bombardment of Pu. | |
| Isotopes: 14 whose half-lives are known, mass numbers 232 to 247. Americium has no naturally occuring isotopes. Its longest lived isotopes are 243Am, with a half-life of 7370 years and 241Am with a half-life of 432.2 years. | |
