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Speed of light
I thought the speed-of-light barrier made "atoms" of elements above 137 impossible, although ions may be possible further. And there is some level where the nucleus would be seriously unstable with respect to spontaneous beta decay or virtual electron capture. Still, this table doesn't require the element to be physically possible, only to be named. —
Arthur Rubin(talk)12:40, 29 October 2012 (UTC)reply
The speed of light isn't actually a limit on the periodic table: see
this discussion. Beta decay is probably somewhat suppressed for superheavy elements: the heaviest element known to undergo beta decay is
Db (element 105), and superheavy elements have an extremely dense electron cloud near the nucleus (due to both relativistic effects and very high atomic number); since electrons must obey the Pauli exclusion principle, beta decay is probably somewhat suppressed (see
Talk:Ununpentium#Stable E115). Such heavy nuclei should be, however, very unstable to
spontaneous fission. If the spontaneous fission half-life of such a nuclide is definitely able to be observed currently, then we need Z2/A ≥ 47. This value is 32.3 for 208Pb (the heaviest known stable doubly-magic nucleus) and 35.5 for 238U, but these values are much higher for the next predicted doubly-magic nuclei: 43.6 for 298Fl, 47.4 for 304120 and 51.2 for 310126.
Double sharp (
talk)
13:59, 29 October 2012 (UTC)reply
Elements 211-218 notice
They should not be re-added untill there's a sourse that carries the idea that these elements can ever exist. Even the 210 limit has be dismissed by most, higher than 210 is unheard of.
Robo37 (
talk)
19:42, 1 November 2012 (UTC)reply
I can still not see a source whereas professional scientists have said that there any chance of these elements being possible. "They've been wrong before!" is not a source.
Robo37 (
talk)
22:27, 1 November 2012 (UTC)reply
We're changing consensus on the template based on a quote from the 1970s? I think we need a little more discussion than that. —
kwami (
talk)
06:07, 7 December 2012 (UTC)reply
It also says that Z = 173 does not constitute an end for neutral atoms: "The bound-state energy then 'dives' into what is called the negative continuum: a vacuum 'sea' of negative-energy electrons predicted by the Dirac equation. Then the 1s states mix with those in the continuum to create a bound 'resonance' state - but the atom remains stable." (from the same site, stated by Ball (not Greiner)). Reverted back. (But we should really change to a relativistic periodic table everywhere – it's what scientists actually use, and is, well, actual science.)
Double sharp (
talk)
07:30, 7 December 2012 (UTC)reply
Then we should use a relativistic table. Meanwhile, you have not provided any ref that these elements are claimed to exist. 173 may be stable, but the article says nothing of higher #s, and we have several refs which do not allow more. Since this is a contentious area, please reach consensus rather than edit warring. —
kwami (
talk)
07:34, 7 December 2012 (UTC)reply
Want a ref for those elements?
Here's Fricke writing in 1971 (p. 480), speculating on the properties of some early period 10 elements (Z ≥ 173), going to Z = 184. He completely ignores the Z=173 limit (though he does mention it in an earlier paper).
Double sharp (
talk)
07:40, 7 December 2012 (UTC)reply
Why are we ref'ing a 1971 paper in 2012? Has our understanding of nuclear physics not advanced in the last 40 years? I doubt anything more than 10 yrs old would be acceptable to many people. —
kwami (
talk)
07:42, 7 December 2012 (UTC)reply
Nobody seems to have done much with elements beyond 172 (the end of period 9) for some time (Pyykkö goes no further, but he does cite Fricke's paper). I think we should just switch to a relativistic table (but then we must get rid of the blocks' colours in favour of something like our colour scheme for the unextended PT).
Double sharp (
talk)
07:44, 7 December 2012 (UTC)reply
Quite simply, because after Z = 173 the 1s shell dives into the negative continuum. The details of what happens after that are not entirely sure, but from what I understand they result in rapid disintegration of the atom so that it cannot be considered an element per IUPAC's 10−14-second-lifetime limit.
Double sharp (
talk)
15:43, 7 November 2016 (UTC)reply
Actually it may not be a bad idea, given that Seaborg's extended table only went to eight periods. I don't think anyone at the time seriously thought about a ninth period, since the second island was supposed to only be at Z = 164.
Double sharp (
talk)
13:55, 15 November 2016 (UTC)reply
Restored the second IP's version to 168 per Seaborg (10.1021/ar00054a003), who stopped there. (It also has the beneficial side effect of halting the first IP's trolling.)
Double sharp (
talk)
13:58, 15 November 2016 (UTC)reply
This template is supported by WikiProject Elements, which gives a central approach to the
chemical elements and their
isotopes on Wikipedia. Please participate by editing this template, or visit the
project page for more details.ElementsWikipedia:WikiProject ElementsTemplate:WikiProject Elementschemical elements articles
This template has been rated as Low-importance on the
importance scale.
This template was considered for
deletion on 2018 May 29. The result of the discussion was "keep".
Speed of light
I thought the speed-of-light barrier made "atoms" of elements above 137 impossible, although ions may be possible further. And there is some level where the nucleus would be seriously unstable with respect to spontaneous beta decay or virtual electron capture. Still, this table doesn't require the element to be physically possible, only to be named. —
Arthur Rubin(talk)12:40, 29 October 2012 (UTC)reply
The speed of light isn't actually a limit on the periodic table: see
this discussion. Beta decay is probably somewhat suppressed for superheavy elements: the heaviest element known to undergo beta decay is
Db (element 105), and superheavy elements have an extremely dense electron cloud near the nucleus (due to both relativistic effects and very high atomic number); since electrons must obey the Pauli exclusion principle, beta decay is probably somewhat suppressed (see
Talk:Ununpentium#Stable E115). Such heavy nuclei should be, however, very unstable to
spontaneous fission. If the spontaneous fission half-life of such a nuclide is definitely able to be observed currently, then we need Z2/A ≥ 47. This value is 32.3 for 208Pb (the heaviest known stable doubly-magic nucleus) and 35.5 for 238U, but these values are much higher for the next predicted doubly-magic nuclei: 43.6 for 298Fl, 47.4 for 304120 and 51.2 for 310126.
Double sharp (
talk)
13:59, 29 October 2012 (UTC)reply
Elements 211-218 notice
They should not be re-added untill there's a sourse that carries the idea that these elements can ever exist. Even the 210 limit has be dismissed by most, higher than 210 is unheard of.
Robo37 (
talk)
19:42, 1 November 2012 (UTC)reply
I can still not see a source whereas professional scientists have said that there any chance of these elements being possible. "They've been wrong before!" is not a source.
Robo37 (
talk)
22:27, 1 November 2012 (UTC)reply
We're changing consensus on the template based on a quote from the 1970s? I think we need a little more discussion than that. —
kwami (
talk)
06:07, 7 December 2012 (UTC)reply
It also says that Z = 173 does not constitute an end for neutral atoms: "The bound-state energy then 'dives' into what is called the negative continuum: a vacuum 'sea' of negative-energy electrons predicted by the Dirac equation. Then the 1s states mix with those in the continuum to create a bound 'resonance' state - but the atom remains stable." (from the same site, stated by Ball (not Greiner)). Reverted back. (But we should really change to a relativistic periodic table everywhere – it's what scientists actually use, and is, well, actual science.)
Double sharp (
talk)
07:30, 7 December 2012 (UTC)reply
Then we should use a relativistic table. Meanwhile, you have not provided any ref that these elements are claimed to exist. 173 may be stable, but the article says nothing of higher #s, and we have several refs which do not allow more. Since this is a contentious area, please reach consensus rather than edit warring. —
kwami (
talk)
07:34, 7 December 2012 (UTC)reply
Want a ref for those elements?
Here's Fricke writing in 1971 (p. 480), speculating on the properties of some early period 10 elements (Z ≥ 173), going to Z = 184. He completely ignores the Z=173 limit (though he does mention it in an earlier paper).
Double sharp (
talk)
07:40, 7 December 2012 (UTC)reply
Why are we ref'ing a 1971 paper in 2012? Has our understanding of nuclear physics not advanced in the last 40 years? I doubt anything more than 10 yrs old would be acceptable to many people. —
kwami (
talk)
07:42, 7 December 2012 (UTC)reply
Nobody seems to have done much with elements beyond 172 (the end of period 9) for some time (Pyykkö goes no further, but he does cite Fricke's paper). I think we should just switch to a relativistic table (but then we must get rid of the blocks' colours in favour of something like our colour scheme for the unextended PT).
Double sharp (
talk)
07:44, 7 December 2012 (UTC)reply
Quite simply, because after Z = 173 the 1s shell dives into the negative continuum. The details of what happens after that are not entirely sure, but from what I understand they result in rapid disintegration of the atom so that it cannot be considered an element per IUPAC's 10−14-second-lifetime limit.
Double sharp (
talk)
15:43, 7 November 2016 (UTC)reply
Actually it may not be a bad idea, given that Seaborg's extended table only went to eight periods. I don't think anyone at the time seriously thought about a ninth period, since the second island was supposed to only be at Z = 164.
Double sharp (
talk)
13:55, 15 November 2016 (UTC)reply
Restored the second IP's version to 168 per Seaborg (10.1021/ar00054a003), who stopped there. (It also has the beneficial side effect of halting the first IP's trolling.)
Double sharp (
talk)
13:58, 15 November 2016 (UTC)reply