Americium

Artificial element (No. 95), made by bombarding uranium or plutonium with helium ions.
A radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms; SYN. Am, atomic number 95.
Radioactive metallic element of the actinide series, symbol Am, atomic number 95, atomic weight 243.13; it was first synthesized 1944. It occurs in nature in minute quantities in pitchblende and other uranium ores, where it is produced from the decay of neutron-bombarded plutonium, and is the element with the highest atomic number that occurs in nature. It is synthesized in quantity only in nuclear reactors by the bombardment of plutonium with neutrons. Its longest-lived isotope is Am-243, with a half-life of 7,650 years.
The element was named by Glenn Seaborg, one of the team who first synthesized it in 1944, after the United States of America. Ten isotopes are known. + prikaži više