Americium
Definition and meaning of Americium in chemistry.
Americium is a synthetic radioactive chemical element with the symbol Am and atomic number 95. It is a member of the actinide series and is located just after plutonium on the periodic table.
In more detail
Americium is a relatively soft, silvery white metal that tarnishes slowly in dry air at room temperature. It does not occur naturally and is produced through multiple neutron captures by plutonium isotopes in nuclear reactors. The most common oxidation state for americium is +3, though it can also exist in states ranging from +2 to +7. Americium is positioned in the f-block, and its chemical behavior closely resembles that of the lanthanides, particularly its homologue europium. The high radioactivity of its isotopes, primarily alpha decay, causes the metal to glow in the dark and necessitates heavy shielding during handling.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Am |
| Atomic number | 95 |
| Atomic mass | [243] u |
| Category | Actinide |
| State at room temperature | Solid |
| Year discovered | 1944 |
| Melting point | 1176 degrees Celsius |
Americium-241 is widely used in commercial ionization chamber smoke detectors as a source of ionizing alpha particles.
Frequently asked questions
How is americium used in smoke detectors?
It emits alpha particles that ionize the air in a detection chamber, and the disruption of this current by smoke particles triggers the alarm.
What is the most stable isotope of americium?
Americium-243 is the most stable isotope, possessing a half-life of approximately 7370 years.