Discovery date : 1944
Discovered by: Glenn Seaborg and colleagues
Origin of the name: Americium is named for America where it was first made.
Allotropes :
~>AMERICIUM is a synthetic chemical element with symbol Am and atomic number 95. It is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas.
| FACT BOX | |||
| Group | Actinides | Melting point | 1176°C, 2149°F, 1449 K |
| Period | 7 | Boiling point | 2011°C, 3652°F, 2284 K |
| Block | f | Density (g cm−3) | 12 |
| Atomic number | 95 | Relative atomic mass | [243] |
| State at 20°C | Solid | Key isotopes | 241Am,243Am |
| Electron configuration | [Rn] 5f77s2 | CAS number | 7440-35-9 |
| ChemSpider ID | 22405 | ChemSpider is a free chemical structure database | |
This element was in fact discovered after curium, the element which follows it in the periodic table. However, it did once exist on Earth having been produced for millions of years in natural nuclear reactors in Oklo, Gabon. These ceased to function a billion years ago, and as the longest lived isotope is americium-247, with a half-life of 7370 years, none has survived to the present day. Americium was first made late in 1944 at the University of Chicago by a team which included Glenn Seaborg, Ralph James, Leon Morgan, and Albert Ghiorso. The americium was produced by bombarding plutonium with neutrons in a nuclear reactor. This produced isotope americium-241, which has a half-life of this is 432 years.