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Article changed over to new Wikipedia:WikiProject Elements format by mav 05:55, 26 Apr 2004 (UTC). Elementbox converted 11:29, 17 July 2005 by Femto (previous revision was that of 23:35, 11 July 2005).

Information Sources

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Americium. Additional text was taken directly from the Elements database 20001107 (via and WordNet (r) 1.7 (via Data for the table were obtained from the sources listed on the subject page and Wikipedia:WikiProject Elements but were reformatted and converted into SI units.


I am not sure how to add titles to the references.




Ref 4 The coordination chemistry of 1,2,4-triazinyl bipyridines with lanthanide(III) elements – implications for the partitioning of americium(III)

Ref 5 Separation Studies of /f/-Elements


what is the hardness of americium? (

Sorry, no hard (pun intended) numbers. Expanded the article from CRC Handbook "It appears to be more malleable than uranium or neptunium [...]". Femto 12:04, 21 November 2005 (UTC)

Spoiler Suggestion

Americium 239 is used in Splinter Cell 1. But I am not going 2 add this as I do not know if this has any place in a science article. --The1exile 18:56, 12 December 2005 (UTC)

    I've seen these sorts of things in other articles, under the heading "Fictional Applications", in the Applications section.  —Preceding unsigned comment added by (talk) 01:54, 4 November 2008 (UTC) 

apparent inconsistency

The article says that americium-241 comes from plutonium-241 by beta decay, but when I look at the plutonium page, I am told that plutonium-241 decays to a uranium isotope.

--Publunch 23:53, 8 January 2006 (UTC)

Plutonium-241 has two decay modes. By far the dominant decay mode is beta decay, which yields americium-241. There is a tiny (0.002%) probability of alpha decay, which yields uranium-237. The statement on the plutonium page that you refer to has apparently since been removed. Piperh 21:07, 19 February 2007 (UTC)

'This element can be produced in kilogram amounts' - how? Do we have to thank our friends at Sellafield for our smoke detectors?

I think so, according to :
"n.Uses: Americium-241 is made in large quantities in nuclear reactors and is available to qualified users in the U.S. and the U.K. It is used as a portable source of X-rays, as a source of ionization for smoke detectors, and as a radioactive glass thickness gauge for the flat-glass industry." 01:18, 27 March 2006 (UTC) tygr007

There is another apparent inconsistency in which the text of the article claims that Am-241 emits gamma rays, but the table in the sidebar clearly indicates that it decays by Alpha emission. —Preceding unsigned comment added by (talk) 16:26, 7 December 2008 (UTC)

Most radiodecays also produces gamma, which isn't mentioned. Rursus dixit. (mbork3!) 20:02, 27 February 2011 (UTC)
Americium-241 α decay also produces numerous X-ray/gamma photons with the 13.9 Kev, 17.8 Kev and 59.5 Kev energies being the most probable. Delphwhite (talk) 00:30, 16 June 2011 (UTC)

Use in nuclear soil moisture gauges

It's use in said gauges might be a valid addition to this article

Ordosingularis 19:46, 9 September 2006 (UTC)

Amount in a smoke detector

Here is a proof that the mass of 0.9 μCi of 241Am (typical amount in a modern smoke detector) is closer to 0.2 μg than 0.2 mg.

The decay rate of a sample of a radionuclide is equal to , where t1/2 is the half-life and N is the number of atoms of that nuclide.

Here the decay rate is 0.9 x 10-6 x 3.7 x 1010 disintegrations per second and t1/2 = 432.2 x 365.25 x 24 x 60 x 60 seconds. So N = 6.55 x 1014 atoms of 241Am which is equivalent to a mass of N x 241.06 / (6.022 x 1023) = 0.26 x 10-6 g. Warut (talk) 07:47, 26 February 2008 (UTC)


I was concerned about the wording of "...and apparently has the consistency of..." This is supposed to be factual, not speculation. Is there any way to fix this and find a better source on its physical properties? ForestAngel (talk) 20:05, 19 August 2009 (UTC)

It's quite possible that scientists have only partial data, and that the wording may be trying to express this. However, this point is currently unsourced, so it's hard to tell. --JWB (talk) 21:18, 19 August 2009 (UTC)

For those new to radiochemistry

Nuclei that emit radiation typically also emit a "gamma" ray photon to conserve momentum. The only exception I can think of is Beryllium-8 where Alpha particles (Helium nuclei)are discharged 180 degrees from each other. Same holds true for Beta radiation (electrons or positrons) which also includes the energy of the neutrino particle emitted on conversion of neutron to proton and vice versa. When Alpha or Beta radiation is stopped by an atom (Alpha interact too strongly (charge +2) to penetrate skin, Beta (charge +1 or -1) stopped by Aluminum foil) they emit a photon, typically gamma ray. Mechanisms range from Cherenkov radiation, Bremstraulung, and others. Gamma ray energy is given as a maximum trailing off to zero energy depending on the angle of emmission from the other particle(s).

I use photon inre the reference to 59 KeV Gamma ray because that would be equivalent to ~55KeV X-ray emitted by television set CRT. Has been fatal to canaries. About low end of dental xray strength. Tritium xrays at 18Kev don't penetrate skin. Shjacks45 (talk) 00:45, 29 January 2010 (UTC)


Production method

Americium is produced in nuclear reactors by bombarding uranium or plutonium with neutrons not alpha particles. I suspect that the amount of Am in spent nuclear fuel would depend greatly on the reactor fuel - a reactor using Pu-239 should produce much more Am than a reactor using U-235 or U-233. (talk) 07:34, 25 January 2011 (UTC)


I've removed the following from the article on the grounds that it's unsourced and, I think, pretty questionable: "For instance in the UK it is permissible to dispose of an americium containing smoke detector by placing it in the dustbin with normal household rubbish, but each filled dustbin is limited to contain not more than one smoke detector." I haven't heard of such a rule, and the "one per dustbin" restriction doesn't sound like the kind of waste disposal regulation that you encounter in the UK. As an electronic device, smoke detectors would presumably be covered by the WEEE Directive in the UK, meaning that you're not meant to put them out with normal rubbish on the grounds that they are waste electronics, regardless of the presence of radioactive material. Does anyone know anything more about disposal regulations for americium smoke detectors? If so, it would be great to have this in the article, all properly sourced of course. Beorhtwulf (talk) 15:46, 28 February 2011 (UTC)


There is a discussion at Talk:Periodic table#Americium is also found in nature, reproduced below. Lanthanum-138 (talk) 05:06, 27 May 2011 (UTC)

<begin copied discussion>

Americium is also found in nature

I am aware that most sources state that the number of elements found in nature is 94 (those with atomic numbers 1-94). However, several other sources raise that number to 95, and include americium (atomic number 95) to those elements found in nature. I hold a copy of "HUTCHINSON GALLUP Info 95" (Hellicon Publishing Ltd., UK, 1994) that states: "Of the [109] known elements, 95 are known to occur in nature (those with atomic numbers 1-95)" (page 459). Another source that includes americium to the elements that are found in nature is "The Free Dictionary by Farlex" that states: "[Americium] 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". This source can be found online here: The above quote is reproduced in several other web sites, eg.: Perhaps the confusion arises from two facts: 1) Quantities of americium (and curium) have recently been found in nature as a by-product of the operation of nuclear reactors and nuclear explosions (ref: This, however, doesn't mean that americium cannot be found as a naturally occurring element as well. 2) Americium was first synthesized in 1944. The fact that it was synthesized before it was discovered as a naturally occurring element should not exclude it from the list of the elements that are found in nature. In fact, technetium and promethium are included in the list, even though they both have been artificially produced before they were found in nature. I would like to have some feedback on the topic. CostaDax (talk) 18:12, 15 February 2011 (UTC)

I can't access your "offline" sources, but the online one seems in order. So if you're certain of it, just be bold and change the table (Periodic table (standard)) to make Am's "natural occurrence" be "From decay". (Or maybe discuss it on the americium article's talk page as well.)--Roentgenium111 (talk) 15:35, 10 May 2011 (UTC)

<end copied discussion>

Thanks, Lanthanum-138 (talk) 05:06, 27 May 2011 (UTC)

Although I'm not sure about this because 239Pu (which is what's usually meant by "neutron-bombarded plutonium") decays to 235U, not 239Am (which in fact decays to 239Pu). If they meant 244Pu, the only other natural isotope of plutonium, it does not decay to Am either, but to 240U and (occasionally) 244Cm. That creates:

244Pu --> 244Cm --> 240Pu* --> 236U --> 232Th and the rest is the beaten track of the thorium (4n) series.

*Or 240Pu --> 206Hg --> 206Tl --> 206Pb.

So if these (doubtlessly extremely rare) chains do happen, then only curium (Z = 96) would be naturally produced, not americium (Z = 95) Lanthanum-138 (talk) 05:21, 27 May 2011 (UTC)

This has also been posted at Talk:Curium. Lanthanum-138 (talk) 05:22, 27 May 2011 (UTC)
R8R Gtrs points out that 239Pu + 2 n → 241Pu → 241Am is possible (see Wikipedia talk:WikiProject Elements/Archive 11#Americium and curium). However, "The Free Dictionary by Farlex" states that the naturally occuring isotope is 239Am and not 241Am. Double sharp (talk) 08:54, 30 January 2012 (UTC)