Talk:Curium

Article changed over to new Wikipedia:WikiProject Elements format by mav 04:07, 7 Apr 2004 (UTC). Elementbox converted 11:36, 17 July 2005 by Femto (previous revision was that of 13:45, 9 July 2005).

Information Sources

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Curium. Additional text was taken directly from the Elements database 20001107 (via dict.org) and WordNet (r) 1.7 (via dict.org). 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.

---

---

Curium-247 - ideal small reactor/nuke power source?

It said to have "bare sphere" critical mass of 7 kg (Pu-239 is 10 kg (or 16 kg - Wikipedia disagees with itself on this)), yet half-life is 15 million years. Should it be mentioned? Where mass and W/kg are very critical (e.g. nuclear propulsion in space), it may make it rather useful, I think. (closest contenders: Np-236: 7 kg, 154000 years; californium-249, californium-251: 5-6 kg, <1000 years).

---

Curium: watts per gram correction

From the research I see curium 242 gives off 120watts per gram not 2! [1] --BerserkerBen 03:14, 9 November 2005 (UTC)

Also http://aaa.nevada.edu/pdffiles/Microsoft%20Word%20-%20Task%2011%20QR%2001-2.pdf - more than I ever wanted to know about thermal effects in curium, but it's a nice reference and confirms the approx. 120 W/g for Cm-242, so I'll put it here. Femto 19:42, 10 November 2005 (UTC)

Natural occurance

Curium has some rather long-lived isotopes. I have read from several sources that it probably exists in trace amounts in natural uranium deposits. It makes sense, but I am not sure if it is true. --Ferocious Flying Ferrets 19:32, 9 April 2010 (UTC)

It is reasonable to assume that it exists in nature, but the long lived isotopes should be primordial, and more short lived ones trace elements in natural ore. However, I believe it will be very hard to detect its presence, partially because of the atomic bomb tests. I presume the rumors are just reasonable speculation. Rursus dixit. (^mbork³!) 12:12, 30 November 2010 (UTC)

It is interesting to note that the half lives of primordial Pu-244 (8.0 * 10⁷y) and Cm-247 (1.67 * 10⁷y) are comparable. So can we consider curium-247 to be primordial? Anoop.m (talk) 18:09, 6 March 2011 (UTC)

No, this factor-4 difference is still too large: primordial Pu-244 passed some 60 half-lives while Cm-247 had ~250 half-lives. So the ratio between present and original primordial Cm-247 would be of order 2^-250≈10^-80, much less than a single atom in the total Earth. OTOH, several atoms from each kg of original Pu-244 still remain.--Roentgenium111 (talk) 12:30, 3 June 2011 (UTC)

Correct – I missed that. And there's approx 1.33×10⁵⁰ atoms in earth (Atom#Earth), meaning that if all Earth originally was made of Curium, then only 9th decillion (9×10⁻³³) part of one Curium atom should remain. Almost zero, that is.

Primordial Curium is extremely improbable on Earth, unless a very improbable passers-by supernova got the improbable idea of improbably sprinkling it into the solar system some few million years ago. Rursus dixit. (^mbork³!) 10:18, 17 July 2011 (UTC)

Uhhhh… but ²⁴⁴Pu only emits alpha particles (99.88%) or goes under spontaneous fission (0.12%). Also, ²⁴⁴Pu, despite the key source, is a synthetic nuclide, so ²⁴⁴Cm, and thus the element curium, is synthetic. That concludes our discussion. --3.14159265358pi (talk) 23:38, 5 December 2011 (UTC)

References

• Rimshaw, S.J.; Ketchen, E.E. (1969). "Curium Data Sheets". doi:10.2172/4827212. {{cite journal}}: Cite journal requires |journal= (help)
• "The Fission Properties of Curium Separated from Spent Nuclear Fuel" (PDF). University of Nevada, Las Vegas.
• Nash, Kenneth; Choppin, Gregory (1997). "Separations Chemistry for Actinide Elements: Recent Developments and Historical Perspective". Separation Science and Technology. 32: 255. doi:10.1080/01496399708003198.

GA Review

This review is transcluded from Talk:Curium/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Casliber (talk · contribs) 13:23, 18 April 2011 (UTC)

Okay - will begin a review and jot queries below. I'll make straightforward copyedits as I go, so correct me if I inadvertently change the meaning. Casliber (talk · contribs) 13:23, 18 April 2011 (UTC)

Curium is a hard, dense silvery metal with relatively high for actinides melting and boiling points. - had to read this sentence twice. I think it'd be better as "Curium is a hard, dense silvery metal with a relatively high melting and boiling point for an actinide."

link or explain "ambient conditions"

ok, make sure all refs are formatted consistently - so Smith, J.; Jones, F. etc. for authors (I like to try and get as many full names as possible but that's just me :)) and completely. Will be back tomorrow.

About 20 radioisotopes and 7 nuclear isomer between - "isomers"?

Soil analysis revealed about 4,000 higher concentration of curium - 4,000 times higher?

the isotope with a halflife of millions of years, is it less radioactive then?

Fixed all the above. Sorry, I don't understand the "less radioactive" question. Materialscientist (talk) 01:10, 19 April 2011 (UTC)

I was wondering whether an isotope with a really long half life meant that it emitted radiation at a very slow rate (?) and was hence less dangerous (??) Nuclear energy and radioactivity were never my strong points :/ Casliber (talk · contribs) 13:48, 27 April 2011 (UTC)

same here :-), but we can always use common sense: in their decay chain, isotopes emit different types of radiation, which all pose different dangers. Also, our body accumulates isotopes very differently (say, it does need iodine, no matter the isotope, but not curium). Thus lifetime alone is not an indicator. If we ignore all that, then the issue is the accumulated dose (peak intensities are usually too small to kill). Isotopes with faster decay are easier to deactivate - just leave them alone for a while. Thus generally, slower ones are considered more dangerous. Materialscientist (talk) 01:07, 28 April 2011 (UTC)

D'oh! forgot about the decay chain! Casliber (talk · contribs) 01:21, 28 April 2011 (UTC)

• The article still has some 6 fact tags. Nergaal (talk) 17:44, 18 April 2011 (UTC)

Agree the fact tags will need to be addressed. I will revisit this once I see some action on the above and find some more stuff to fix. Ultimately as this is a core science article (an element), I am happy to leave this GAN open longer if we can get a better result and if I see movement along the way. Casliber (talk · contribs) 22:53, 18 April 2011 (UTC)

Resolved. Yes, some of it was reasonable WP:OR and the tags were rather appropriate. Materialscientist (talk) 01:10, 19 April 2011 (UTC)

Um, hello, everybody? This GA nomination seems to have sort of died (last post by Materialscientist 8 days ago). Lanthanum-138 (talk) 11:12, 27 April 2011 (UTC)

Oops, sorry. I'll look over it again and update anon. Casliber (talk · contribs) 12:06, 27 April 2011 (UTC)

Para 2 in the Occurrence section talks about where it is found - sentence 3 (" Even higher ratio of about 18,000 was measured in loam soils") presumably needs and "An" at the beginning.

All page range refs should have periods - some currently do and some don't.

refs 55, 61, 63, 67, 76 all have initials with periods missing after them. There might be others too. (I added this as I thought this might be heading to FAC at some time)

can other info be added to refs 80, 84, 85, 86 and 87 at all?

Thanks. I've added "an" and reference details where possible. References would need an upgrade for FAC, which was not my intention. Materialscientist (talk) 01:07, 28 April 2011 (UTC)

Okay, I won't let a few dots hold up a GA, so I think we're over the line here.

1. Well written?:

Prose quality: (could probably be tweaked a little more but no deal-breakers left)

Manual of Style compliance:

2. Factually accurate and verifiable?:

References to sources:

Citations to reliable sources, where required:

No original research:

3. Broad in coverage?:

Major aspects:

Focused:

4. Reflects a neutral point of view?:

Fair representation without bias:

5. Reasonably stable?

No edit wars, etc. (Vandalism does not count against GA):

6. Illustrated by images, when possible and appropriate?:

Images are copyright tagged, and non-free images have fair use rationales:

Images are provided where possible and appropriate, with suitable captions:

Overall:

Pass or Fail: - tricky as I am not an expert in the area but I think it looks pretty comprehensive etc. Anyway, pass now. Casliber (talk · contribs) 01:21, 28 April 2011 (UTC)

Natural?

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: http://encyclopedia.farlex.com/Americium-239 The above quote is reproduced in several other web sites, eg.: http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0009901.html 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: http://www.hps.org/publicinformation/ate/q650.html). 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:Americium. Lanthanum-138 (talk) 05:23, 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) 08:56, 30 January 2012 (UTC)

Stability characteristics

The isotope EO96Cu247 is reported to be the longest halflife isotope of this element. It would consist in 96 Deuterons plus 55 extra neutrons and a stability line characteristic of A = 3Z - 41. This atom could not have a balanced structure.WFPM (talk) 12:19, 28 May 2012 (UTC)