am

Americium (symbol Am) is a synthetic radioactive chemical element in the actinide series with atomic number 95. It is not found in appreciable quantities in nature and is produced in nuclear reactors as a byproduct of plutonium production. The name Americium comes from the Americas, following a naming convention for some actinides.

Physically, americium is a silvery metal that tarnishes in air, forming an oxide layer. It exhibits multiple oxidation states, commonly +3 and +4, with higher states such as +5 and +6 in some compounds. All isotopes are radioactive; the most important is americium-241, which decays by alpha emission with a half-life of 432.2 years to neptunium-237.

Isotopes and production: Am-241 is produced in reactors from plutonium-241 by beta decay and irradiation processes; Am-242m is a metastable isotope used mainly in research.

Applications: The best-known use is as a compact alpha source in ionization smoke detectors. It is also used in some industrial gauges and research laboratories as a neutron source when combined with beryllium (Am-Be sources).

Discovery and history: Americium was first synthesized in 1944 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso at the Metallurgical Laboratory, University of Chicago, during the Manhattan Project. It was named after the Americas.

Safety: Americium is highly radioactive and requires shielding and containment. Handling and disposal are regulated because of risks from ingestion, inhalation, and external exposure.