| From Wikipedia, the free encyclopediaAmericium is a radioactive transuranic chemical element with symbol Am and atomic number 95. This member of the actinide series is located in the periodic table under the lanthanide element europium, and thus by analogy was named after the Americas. Americium was first produced in 1944 by the group of Glenn T.Seaborg from Berkeley, California, at the metallurgical laboratory of University of Chicago. | |||||||||
Americium in the periodic table | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | Am | ||||||||
| Atomic number | 95 | ||||||||
| Group | 0 | ||||||||
| Period | 7 | ||||||||
| Block | f | ||||||||
| Element category | Actinide | ||||||||
Physical properties | |||||||||
| Phase at STP | Solid | ||||||||
| Density | 12 g/cm3 | ||||||||
| Atomic weight | 243 u | ||||||||
| Melting point | 1449 K 1175.85 °C 2148.53 °F | ||||||||
| Boiling point | 2880 K 2606.85 °C 4724.33 °F | ||||||||
Atomic properties | |||||||||
| Electronegativity (Pauling Scale) | 1.13 | ||||||||
| Electron affinity | 9.93 kJ/mol | ||||||||
| Oxidation states | +2, +3, +4, +5, +6, +7 (an amphoteric oxide) | ||||||||
| Ionization energies |
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Electron configuration | |||||||||
| Elektronkonfiguration (shorthand) | [Rn] 5f7 7s2 | ||||||||
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f7 6s2 6p6 7s2 | ||||||||
| Electrons per shell | 2, 8, 18, 32, 25, 8, 2 | ||||||||
History | |||||||||
| Discovered | 1944 | ||||||||
| Discovered by | Glenn T. Seaborg R. A. James Leon O. Morgan A. Ghiorso | ||||||||