Americium
Americium is a radioactive chemical element with the symbol Am and the atomic number 95. In chemistry, it is placed in a group of metal elements named the actinides. Americium is a transuranic element (Transuranic means after uranium as all the elements used after uranium are man-made). Americium does not exist in nature and has to be made by people. It has a silver color. Americium is made by bombarding a plutonium target with neutrons.
It was the fourth transuranic element to be discovered. It was named for the Americas, like europium was named for Europe.[1][2]
The longest half life of any type of americium is 7370 years.[3]
How it's made
Americium is a synthetic element. It must be made by people and is not found in nature. Most americium is made as a byproduct of nuclear reactors, and can be separated out during nuclear reprocessing.
The two most stable isotopes of americium are 241
Am and 243
Am. They are made by beta decay of the same-weight plutonium isotopes, 241
Pu and 243
Pu, which are made from neutron capture in thermal reactors.
Most americium is 241
Am. 241
Pu has a 14 year half-life and large fission cross section, so decaying to americium is rare in active reactors. Most 241
Am is found in spent nuclear fuel, where plutonium is more likely to decay than go through fission. 241
Am is also a byproduct of nuclear weapons production, which needs to separate 241
Pu from 239
Pu to produce weapons-grade plutonium.
Uses
Americium is used in ionization-type smoke detectors. The level of radioactivity is not enough to cause cancer, and it cannot get through the smoke detector's plastic case, so it is safe to live in a place where smoke detectors with americium are used. This type of smoke detector is becoming obsolete, and is being replaced by optical smoke detectors, which have fewer false alarms and don't contain radioactive material.
Americium Media
The 60-inch cyclotron at the Lawrence Radiation Laboratory, University of California, Berkeley, in August 1939
Americium was detected in the fallout from the Ivy Mike nuclear test.
Chromatographic elution curves revealing the similarity between the lanthanides Tb, Gd, and Eu and the corresponding actinides Bk, Cm, and Am
Double-hexagonal close packing with the layer sequence ABAC in the crystal structure of α-americium (A: green, B: blue, C: red)
Predicted structure of amerocene [(η8-C8H8)2Am]
References
- ↑ Kostecka, Keith (2008). "Americium – From Discovery to the Smoke Detector and Beyond" (PDF). Bull. Hist. Chem. 33 (2): 89–93. Archived (PDF) from the original on 2022-10-09.
- ↑ "C&En: It's Elemental: The Periodic Table - Americium".
- ↑ "Americium Video - The Periodic Table of Videos - University of Nottingham". www.periodicvideos.com. Retrieved 2022-04-19.
