Talk:Promethium/Archive 1

Information Sources
Some of the text in this entry was rewritten from Los Alamos National Laboratory - Promethium. Data for the table was obtained from the sources listed on the subject page and WikiProject Elements but was reformatted and converted into SI units.

Similarly, does it occur naturally or not? Current article says "Promethium does not naturally occur on Earth" (in Occurence section), but also mentions that "promethium is still recovered from the byproducts of uranium fission." Since uranium undergoes spontaneous fission, does it follow that promethium is produced spontanously as a product of uranium? Jeneralist 22:07, 10 September 2006 (UTC)


 * Yes. It's a tiny amount because only a tiny fraction of the uranium atoms undergo spontaneous fission (as opposed to alpha decay), and only a tiny fraction of those fission events form relatively long-lived isotopes of promethium, but it is produced spontaneously that way. —Keenan Pepper 22:37, 10 September 2006 (UTC)


 * Found a reference in the literature to that effect and updated the "Occurence" section accordingly. Jeneralist 04:59, 17 September 2006 (UTC)

Isotopes
What does this mean?

The isotopes of promethium range in atomic weight from 127.9482600 u (128Pm) to 162.9535200 u (163Pm).

I thought isotopes were in whole numbers and a fractional designation represented a mix of isotopes?


 * An isotope is represented by whole number (total number of neutrons and protons), but the atomic mass of a specific isotope is not due to nuclear binding energy. DMacks 19:08, 10 October 2006 (UTC)

So where this Promethium page says "Promethium's longest lived isotope (atomic weight 145 u)", should that parenthesis really be (mass number 145) ? The actual atomic weight of Pm-145 is 144.912 u or thereabouts. Fathead99 08:12, 10 May 2007 (UTC)
 * Rewritten. Femto 14:19, 10 May 2007 (UTC)

Why is it radioactive?
Why are the elements technetium and promethium radioactive? It is because they are syntheticized? They seem like just two random spots on the periodic table that have no stable isotopes. They are usually artficial, but they can be both found naturally on Earth and in Space. They don't emmit alpha particles, but they do emit beta particles, and some emit gamma particles. Beta particles usually indicate that the isotope has too many or not enough neutrons. However, almost all elements have radioactive isotopes, but these two don't have any stable isotopes. Is there any particular reason why these elements have no known existing isotopes that are non-radioactive, besides the fact that they are usually syntheticated? AstroHurricane001 13:32, 5 December 2006 (UTC)

Just a nit to pick, but all elements have radioactive isotopes. Not all are found naturally, though. Jokem 04:55, 23 June 2007 (UTC)

Since we're nitpicking, is it not true that no isotope is truly stable (with the conceivable exception of Fe), but rather "stable" is a completely arbitrary line across the continuous domain of long half-lives? 150.203.48.127 (talk) 01:37, 8 April 2008 (UTC)


 * I am not enough of a Nuclear Physicist to talk about this, maybe someone else here can comment? My understanding is an isotope is stable if it does not spontaneously emit.  Jokem (talk) 19:15, 15 April 2008 (UTC)


 * I know I'm a year late, but just to let you know, Tc and Pm are not stable because the valley of beta stability lies in an area where both elements around it (Mo and Ru; Nd and Sm) have stable isotopes for each mass number. So Tc and Pm will always undergo beta decay, as they can't find stable configurations. It's a rare effect of the liquid drop model.--121.7.203.206 (talk) 06:39, 22 May 2009 (UTC)


 * And I am a year later, but what I have always been curious about is both are the same number of elements from the left edge of the periodic table. Promethium would appear right under Technetium if the Transition Elements were not shifted right.  There has to be a story there.  Jokem (talk) 04:21, 30 December 2010 (UTC)

Venom?
Has anyone else noticed that one of the listed applications is housing a villian from the Spiderman series? Look, I realise Pm is a pretty useless element and all, but does that excuse including fictional uses for it? (Not that I didn't laugh when I saw it...) —Preceding unsigned comment added by 130.216.91.218 (talk) 23:03, 3 August 2010 (UTC)

This reader notes under subject "Promethium", subsection "True Promethium", last sentence, a statement made that 147Pm has a Half-life of "11 days" whereas assorted adjacents/relateds state a half-life of some 2.6 y. (Trust this isn't a play on there being 6 active/2inactive reactors at Pickering Nuclear station east of Toronto, Canada, and any number witching politics possibly related to it - not wanting to be a rectifying harpist player on this!?)174.117.180.82 (talk) 15:31, 10 April 2011 (UTC)

A few Google Books links just in case anyone wants to "finish" the article (with preview)
Describes how one uses Pm for checking the width of a metal layer

Contains a few physical properties (figures), scroll up

Popular science journal; describes how an atomic battery is organized

a PS journal, too; says the batteries are safe

[http://books.google.ru/books?id=DC0DAAAAMBAJ&pg=PA258&dq=promethium+spelling&hl=ru&sa=X&ei=15kNT876DYud-wa59qiaBw&ved=0CDsQ6AEwAQ#v=onepage&q=promethium%20spelling&f=false a PS journal (again!); reports confirmation of a few chemical elements' names (Pm, Tc, Be, Nd, etc.). Also says that element 74 will be called Wolfram in English (a 1950 article). Well...]

this one is for me: grouping in the group 3 and other nice notes on REE

usage of PmCl3/ZnS in watches --R8R Gtrs (talk) 18:32, 12 January 2012 (UTC)

Predestined Primordial Promethium
It essentially says 2.8×10−9 of all Pm-145 nuclei are predestined to &alpha; decay with a half life of 6.3×109 years, so many of those nuclei are still around from the beginning of the universe and all of them will eventually undergo &alpha; decay only.

This just doesn't sound right to me. First, I thought that the big bang at the start of the universe only formed hydrogen, helium and a little lithium. All other isotopes, including heavy radioactive ones with short half lives, are still regularly formed in supernovae.

Second, I know that certain isotopes can decay in more than one way, but I did not know that individual atoms of the same isotope were predestined to decay in a specific way. I thought that individual nuclei not in different metastable states are indistinguishable and memoryless; any given Pm-145 nucleus will usually &beta; decay, but very rarely one will &alpha; decay instead. I'd like to have someone who knows far more about it than me check out this section. Karn (talk) 06:37, 1 February 2012 (UTC)


 * I was the one to write it. Maybe you want to hear it from me as well.


 * You're right about the element formation thing. I just don't know it much and didn't sweat to find out (turned out surprisingly harder than I thought to find an exact period for Pm or just Z around 61 in any borders, and then a ref). That's why I wrote there wrote "Considering even." If you can fix it, you're really welcome.


 * (WP:V says whatever your source says from the point of view of WP, it's right for WP (not actually, but you get my point, that's exactly what the source writes. A real scientific book...they don't seem to lie.)). Just for you (do not consider the real explanation, but it should be helpful): It also took me days to realize it how it works. If you have the probability of alpha decays, then you can calculate the alpha half-life (Tα=T/log2(2b/2b-a), where a/b is the probability of alpha decay and T is the whole thing half-life... if you very want, I can give you the mathematical proof, but it's unlikely it'll help you; it is also complicated). If you build the curves of decays, they'll be almost identifical, except for going down on different speeds compared to each other but will share the same character (losing a half after an alpha/beta half-life). Therefore, you can conclude that at every moment of time, the ratio of alpha decayed atoms and the number of beta decayed atoms is constant. The mathematical model is not tied to such things as countable atoms. In it you can have 0.37 atoms or as much as you want (just >0). And in it, you still have some atoms that will beta decay (0.0000000000000001, say). And some alpha decaying atoms. Just at present, the number of beta decaying atoms fell way below 1, therefore there is no Pm beta atoms (there MAY BE some actually, the the law of large numbers says that's so unlikely (way below 10-2.5M). Also, no atom is predestined to alpha or beta decay. But we have the alpha probability, the fact that at during any period, alpha and beta decays ratio will be constant. Since the above, and the law of large numbers, the situation described is likely to be true. (Again, very very very very extremely small probability for the reverse). No way it'll happen. At least, that's the theory.--R8R Gtrs (talk) 13:07, 2 February 2012 (UTC)
 * Sorry, but this is absolutely wrong. If you have 103 atoms of Pm-145 with partial half-lives of 17.7 yr for beta decay and 6.3 yr for alpha decay, you will lost all your atoms after about 10 * 17.7 yr (10 half-lives decrease the initial number of atoms by 210≈1000 times). Then, 106 atoms would disappear after 2*10*17.7 yr, 1024 atoms (about one mol) -- after 8*10*17.7 yr etc. Even if you take ~one Earth mass of Pm-145 (about 1045 atoms) it would totally decay after 15*10*17.7 yr≈2700 yr. Additional mode of decay can only speed up the decay but cannot slow down it. You can check this by a thought experiment, changing the partial half-life of the additional mode from infinity to zero: the total half-life will decrease from 17.7 yr to 0. The book referenced by you says other thing: the authors meant that the long half-life of alpha decay of 145Pm can give a hope that the beta decaying 145Pm is actually a metastable excited state of this nucleus. In this case, the alpha decaying 145Pm could be a beta-stable ground state and therefore could be naturally occurring. However, this book had been printed in 1966, and since that time, careful studying of level structures and masses of nuclei discarded this possibility. So, I have removed the part about "primordial Pm" as it is not supported by any sources. --V1adis1av (talk) 22:18, 14 February 2012 (UTC)