americium
noun
am·er·i·ci·um
ˌa-mə-ˈri-shē-əm 
-sē-
: a radioactive metallic element produced artificially by bombarding plutonium with high-energy neutrons see Chemical Elements Table
Examples of americium in a Sentence
Recent Examples on the Web
If successful, this process could deal with the americium that is the most dangerous and long-lived component of spent reactor fuel.
—
IEEE Spectrum, 25 Nov. 2024
The energy source is a small amount of the radioactive element americium, embedded in a polymer crystal that converts the radiation into a stable green glow, eerily similar to those old stars everyone had stuck to their childhood bedroom ceiling.
—Michael Irving, New Atlas, 19 Sep. 2024
Alternatively, Cotruvo suggests, captured americium and curium could be recycled back into nuclear fuel.
—Nikk Ogasa, Scientific American, 19 Nov. 2021
Along with americium, the discovery of curium was related to the top-secret Manhattan Project, so no announcement was made until WWII ended.
—Allison Futterman, Discover Magazine, 17 Sep. 2022
Some of those more obscure elements play fundamental roles in shaping modern-day society: lighter flints use cerium, smoke detectors have americium inside, and color televisions need Europium to function.
—Nathaniel Scharping, Discover Magazine, 7 Nov. 2016
The team created 30 atoms of element 115 by firing a beam of calcium atoms at a piece of americium foil.
—Shannon Palus, Discover Magazine, 19 Dec. 2013
The most stable isotopes of americium and curium decay faster than uranium’s most stable isotopes.
—Scientific American, 1 Apr. 2022
In Colorado, for instance, 27 buildings house scary-sounding elements such as cesium 137, cobalt 60, americium 241 and iridium 192.
—Sarah Scoles, Scientific American, 11 Mar. 2022
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IEEE Spectrum, 25 Nov. 2024
The energy source is a small amount of the radioactive element americium, embedded in a polymer crystal that converts the radiation into a stable green glow, eerily similar to those old stars everyone had stuck to their childhood bedroom ceiling.
—Michael Irving, New Atlas, 19 Sep. 2024
Alternatively, Cotruvo suggests, captured americium and curium could be recycled back into nuclear fuel.
—Nikk Ogasa, Scientific American, 19 Nov. 2021
Along with americium, the discovery of curium was related to the top-secret Manhattan Project, so no announcement was made until WWII ended.
—Allison Futterman, Discover Magazine, 17 Sep. 2022
Some of those more obscure elements play fundamental roles in shaping modern-day society: lighter flints use cerium, smoke detectors have americium inside, and color televisions need Europium to function.
—Nathaniel Scharping, Discover Magazine, 7 Nov. 2016
The team created 30 atoms of element 115 by firing a beam of calcium atoms at a piece of americium foil.
—Shannon Palus, Discover Magazine, 19 Dec. 2013
The most stable isotopes of americium and curium decay faster than uranium’s most stable isotopes.
—Scientific American, 1 Apr. 2022
In Colorado, for instance, 27 buildings house scary-sounding elements such as cesium 137, cobalt 60, americium 241 and iridium 192.
—Sarah Scoles, Scientific American, 11 Mar. 2022
Cite this Entry
“Americium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/americium. Accessed 19 Jul. 2025.
Copy CitationKids Definition
americium
noun
am·er·i·ci·um
ˌam-ə-ˈris-ē-əm
-ˈrish-
: a radioactive metallic element produced by bombardment of plutonium with high-energy neutrons see element
Medical Definition
americium
noun
am·er·i·ci·um
ˌam-ə-ˈris(h)-ē-əm
: a radioactive metallic element produced by bombardment of plutonium with high-energy neutrons
—symbol Am
see Chemical Elements Table
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