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WikiProject Elements (Rated B-class, High-importance)
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Article changed over to Wikipedia:WikiProject Elements format by User:maveric149. Elementbox converted 10:10, 15 July 2005 by Femto (previous revision was that of 18:51, 10 July 2005).

Information Sources[edit]

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Radium. Additional text was taken directly from (input radium into search field) and USGS Periodic Table - Radium. Other information was obtained from the sources listed on the main page but was reformatted and converted into SI units.


I'm a bit puzzled by the description "Transuranic is (SIC) character". It's not actually transuranic, as everyone who follows this link will know.

Can whatever this means be expressed more clearly, I wonder.Andrewa 18:18 Mar 5, 2003 (UTC)

The source of this error appears to be the online elements database which has now been corrected. I have deleted the reference to transuranics on this page. It's still not very elegant prose. Andrewa 05:55 Mar 10, 2003 (UTC)

Melting point[edit]

The article states that the melting point of radium is either 700°C or 960°C, and that there is no scientific consensus as to the correct melting point, and that both values are found in sources. I am unable to find any source later than 1926 (which was the International Critical Tables of Numerical Data, Physics, Chemistry and Technology, Volume I) which lists 960°C as being radium's melting point. Every other source I can find says that radium melts at 700°C (or 696°C, but that's splitting hairs a bit compared to the 260° difference between the values in the article). Would anyone disagree with editing the article to list radium's melting point solely as 700°C (and its equivalent in other units) and removing the reference to this apparently non-existent controversy? JMike93 (talk) 22:12, 5 May 2016 (UTC)

Agreed, the value given in the CRC Handbook of Chemistry and Physics (2009, 89th edition) is 696°C. I suggest we use that value.Polyamorph (talk) 14:14, 6 May 2016 (UTC)
I do not agree, where does the number in CRC come from? Kirby is has written a good review on radium which is quoted several times in our article and he doe s give both values for the melting point. I do not belive that any chemist after the glorious radium years were over had enough material to messure the melting point and so there is the 260°C difference. --Stone (talk) 12:12, 7 May 2016 (UTC)
Already for the stable elements there is a lot of disagreement on boiling point values (e.g. quoted values for Nb have varied from 3573 to 5017 K!). The paper linked has indeed brought down the errors from 900% to 10%, but they couldn't do the radioactive elements. Regulations keep tightening and I seriously doubt we will ever get much better data on the melting point of Ra. There is probably still a frozen controversy here, unseen solely because it froze with the regulations. Double sharp (talk) 13:26, 7 May 2016 (UTC)
The values that Kirby quotes are referenced to articles published in 1910 and 1926! CRC is a pretty rigorous compendium of known physical and chemical properties and they will have checked this! I will search for the actual sources but general references are given in CRC. I don't think it's ridiculous precision if that's the value someone has measured using modern methods, which is comparable to Curie's original 700 deg C value. In any case the CRC handbook is a recognised reliable source for use in chemical info boxes.Polyamorph (talk) 11:49, 9 May 2016 (UTC)
In Melting_points_of_the_elements_(data_page) we give the value 700 deg C from all three sources WEL, CRC and LNG - this is the recommended value to use. I don't then understand why you've chosen to use the higher value which doesn't seem to be reproduced in any other reference literature.Polyamorph (talk) 11:56, 9 May 2016 (UTC)
Also 700 deg C in Kaye and Laby. It would be nice to find the actual reference to the measured 696 value but in any case there is absolutely no mention anywhere in the literature for the higher value other than that ICTND source. I'll change the value to 700 deg C. Polyamorph (talk) 12:11, 9 May 2016 (UTC)

There's another discussion about the m.p. of radium, here. The Curies' write up of the behaviour of radium at around 700°C is interesting and seems to indicate it was volatizing rather than melting. I think changing the value to 700 deg C is rash, or this value at least deserves a qualifying note. Sandbh (talk) 13:32, 14 May 2016 (UTC)

In this 1955 paper, Stites et al. give a melting point of 960 deg C, citing Brewer L 1950, National Nuclear Energy Series, IV-19B, McGraw-Hill, New York pp. 28—32, 103–116, 193—207. They go on to say, "In general, the mp of the elements…decrease with increasing atomic number. However, this observation does not appear to be valid for Period 6. The reported mp of radium (960°) is higher than that of barium (717°). We observed a similar anomaly for actinium (1,050°) and lanthanum (887°). Since the mp of of the metals are related to their atomic volumes, the anomalies are probably due to the effect of the lanthanide contraction. The elements affected by the lanthanide contraction are those in Table III below the line [Fr, Ra, Ac, Hf, Th]. In Group IV, the effect of lanthanide contraction is observed in the fifth period. The mp of hafnium (2,327°) is higher than that of zirconium (1,860°). Therefore the mp for actinium shows both a horizontal and vertical relationship to the mp of its neighbouring elements [Ra, La, Th]. Sandbh (talk) 00:16, 15 May 2016 (UTC)
In her 1911 Noble lecture Marie Curie said, "The metal obtained melts at about 700°C, above which temperature it starts to volatilize."
— Preceding unsigned comment added by Sandbh (talkcontribs) 00:34, 15 May 2016(YBG (talk) 14:39, 15 May 2016 (UTC))
OK, but in general we are supposed to use the values given in reference data sources (like CRC, WEL, LNG - all of which give the value ~ 700 deg C). IF they're wrong, then fine but we need to prove it. Do you have access to the Brewer L 1950 reference? I wonder whether they actually measured it or if it all comes down to the one 1926 International Critical Tables of Numerical Data reference. There is a note to say that the value is disputed, I would be happy for this note to include the 960 value and its reference. Polyamorph (talk) 08:26, 20 May 2016 (UTC)

I still tend to distrust general reference books for rare radioactives. By definition they are not specialising in the element and therefore they would tend to parrot each other, just like how the statement that there are no perastatates still keeps going around. The reason why it makes sense to look at very old sources like this about radium is because due to tightening safety regulations, no one has enough radium metal to determine the melting and boiling points properly today, and so anybody quoting a value must be parroting one from elsewhere. Therefore I have reinstated the disagreement in the main body of the article. I suspect it will remain that way for a long time, because nobody really cares about radium today: all the applications are too dangerous, and it's not even chemically that interesting (just Ra2+, which behaves very similarly to Ba2+). Polonium is more interesting and is somewhat easier to make. Double sharp (talk) 05:32, 16 July 2016 (UTC)

P.S. Just to bring home the point about how little people care about most of these rare radioactives today: Greenwood and Earnshaw cordon off astatine and radon into their little brief sections after the main bodies of the halogen and noble gas chapters, stop mentioning francium and radium after the initial introductory pleasantries, and only make a single mention of actinium chemistry, the formation of the oxychloride, in the group 3 chapter. The actinides up till einsteinium are treated much better, and they really try to talk about polonium in as much detail as selenium and tellurium. Double sharp (talk) 05:39, 16 July 2016 (UTC)

OK, the note you added to the article is good, thanks. Polyamorph (talk) 09:27, 22 July 2016 (UTC)

BTW, the Ullmann source I have since added explains the sad state of affairs fairly well: "Due to decreasing interest in these rare and difficult-to-handle radioelements [Tc, Pm, Po, At, Rn, Fr, Ra, Ac, Pa], no more investigations of special importance – except of 99mTc for nuclear medicine – have been done in the last decade and, therefore, no review papers have been published recently." Double sharp (talk) 14:50, 24 April 2017 (UTC)

(P.S. As another example of this situation; the widely-quoted value of 202 K for the melting point of Rn dates from measurements made in 1909 by Ramsay and Gray (10.1002/anie.201803353), and apparently no future experiments were done ever since to confirm this value. Simulations suggest that it is nonetheless astonishingly accurate.) Double sharp (talk) 07:21, 28 May 2019 (UTC)

Horrible grammar[edit]

"When the mixed sulfate were pure enough they were once more converted to mixed chloride and barium and radium were separated [...]."

That's the kind of awful grammar/punctuation you'll get if you semi-protect articles, IMO, because most people who notice will be blocked from fixing it, but (unlike me?) won't think it merits a dedicated request on the Talk page.
—DIV ( (talk) 08:54, 9 July 2019 (UTC))