Talk:Californium

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Article changed over to new Wikipedia:WikiProject Elements format by mav 08:17, 31 Mar 2004 (UTC). Elementbox converted 11:47, 17 July 2005 by Femto (previous revision was that of 23:40, 10 July 2005). 10 July 2005

Natural Occurrence

This article states that californium is the heaviest element to occur naturally on Earth. What is the source for that statement and is it reliable? Every source I have seen states that plutonium is the last known naturally occurring element on Earth/in the Earth's crust. — Preceding unsigned comment added by 72.84.185.135 (talk) 16:31, 27 October 2012 (UTC)

Emsley, John (2011). Nature's Building Blocks: An A-Z Guide to the Elements (New ed.). New York, NY: Oxford University Press. ISBN 978-0-19-960563-7. Double sharp (talk) 02:35, 28 October 2012 (UTC)

This source is available on Google Books: https://books.google.com/books?id=4BAg769RfKoC&pg=PA109&lpg=PA109&dq=natural+californium&source=bl&ots=k13oE1PMtL&sig=aQ7r-ojSQDF7Dv-kc4rfgdeJOVw&hl=en&sa=X&ei=4ckxVcLqEoXSoATdiYCQAQ&ved=0CEsQ6AEwCDgK#v=onepage&q=natural%20californium&f=false

That is the only source I've ever seen make that claim, and it doesn't cite any outside source nor does it state that any natural californium has ever been detected. It's not implausible that it might occur, but has there ever actually been any detection of it, or any other transplutonium element? If not, should Wikipedia be making this claim? - Bootstoots (talk) 18:01, 6 May 2015 (UTC)

I am extremely doubtful of the claim that californium occurs naturally in the Earth's crust. The book says that 5 isotopes exist naturally, including Cf-253, which has a half-life of only 17.8 days. That seems really far-fetched, even with neutron capture. There is only one source, it is a rather non-technical book, and it doesn't cite any sources for its claims. The claim that californium is natural should be removed from Wikipedia, in my opinion, but I am not sure enough to remove it myself.Fluoborate (talk) 07:32, 15 August 2015 (UTC)

Article discussion

Excuse me, some questions were discussed on Chinese Wikipedia:

• "Californium metal starts to vaporize above 300 °C (570 °F) when exposed to a vacuum."
  • Anything will be vaporized when exposed to a vacuum, so what's the condition of this discription?
• "melting point of 900 ± 30 °C (1,650 ± 50 °F) and an estimated boiling point of 1,745 K (1,470 °C; 2,680 °F)."....
  • Which kind of isotope? The way of estimate?
    • ²⁵²Cf. Estimated by extrapolated vapour pressure, probably. Double sharp (talk) 11:59, 19 August 2016 (UTC)
• "Below 51 K (−220 °C) californium metal is either ferromagnetic or ferrimagnetic (it acts like a magnet), between 48 and 66 K it is antiferromagnetic (an intermediate state), and above 160 K (−113 °C; −172 °F)"
  • What about 66 K to 160 K? Curie point?
• "A double-hexagonal close-packed form dubbed alpha (α) and a face-centered cubic form designated beta (β).[b] The α form exists below 900 °C (1,650 °F) with a density of 15.10 g/cm3 and the β form exists above 900 °C with a density of 8.74 g/cm3.[15] At 48 GPa of pressure the β form changes into an orthorhombic crystal system due to delocalization of the atom's 5f electrons, which frees them to bond.[16][c]"
  • Which kind of isotope? 15.10 possesses four effective digit, what is it's measurement uncertainty? What's the condition of "8.74 g/cm"?---Koala0090 (talk) 09:57, 8 July 2015 (UTC)
    • • If the quoted statement is true, then β-californium is a crystal that exists only above the melting point. How can that be?
      • Solo Owl 04:14, 23 November 2016 (UTC)
        • The transition temperature is very poorly established, as is very common for elements like this: after all in 1974 two purported Cf allotropes turned out to really be hexagonal Cf₂O₂S and fcc CfS. The α-β transition temperature is probably somewhere around 600–800 °C. The melting point is not really known very well either anyway, as it was measured for very small particles, and similarly the crystal structures were determined from microgram quantities of Cf. There is a good reason why knowledge of the detailed chemistry of the actinides is mostly concentrated on the long-lived elements from Th to Pu! (These five and Tc are really the only radioactive elements that have been chemically investigated to a level on par with the stable elements.) Double sharp (talk) 04:30, 23 November 2016 (UTC)
      • Thanks for your quick response. I thought it was like that. Solo Owl 13:49, 23 November 2016 (UTC)

Chemistry

http://www.osti.gov/scitech/servlets/purl/1225199/ Double sharp (talk) 11:59, 19 August 2016 (UTC)

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