Here’s The Mind-Boggling Reason The Periodic Table Doesn’t Seem to Have an End
As researchers around the globe race to create the next element on the periodic table – an atom that contains 119 protons – one scientist from Michigan State University is looking into where the table might end.
more…
Tau.Neutrino said:
Here’s The Mind-Boggling Reason The Periodic Table Doesn’t Seem to Have an EndAs researchers around the globe race to create the next element on the periodic table – an atom that contains 119 protons – one scientist from Michigan State University is looking into where the table might end.
more…
This article opens up a whole raft of thoughts.
According to this graph, we don’t know if we’re already close to the end of the periodic table.
Element 118 already has 176 neutrons in the most stable form, which is close to the magic number of 184 neutrons.
> is there a way to improve the method that is being used now to extend the periodic table?
Superheavy elements created so far have the problem of having the wrong ratio of protons to neutrons – not enough neutrons.
Two possibilities occur to me. One is to immerse isotopes created using traditional methods in the highest possible flux of neutrons, to get them to absorb enough neutrons to get closer to the line of stability.
A second is to detune the LCH to collide lead nuclei head on (which it now does) at lower and lower energies until they merge together rather than flying apart.
mollwollfumble said:
> is there a way to improve the method that is being used now to extend the periodic table?Superheavy elements created so far have the problem of having the wrong ratio of protons to neutrons – not enough neutrons.
Two possibilities occur to me. One is to immerse isotopes created using traditional methods in the highest possible flux of neutrons, to get them to absorb enough neutrons to get closer to the line of stability.
A second is to detune the LCH to collide lead nuclei head on (which it now does) at lower and lower energies until they merge together rather than flying apart.
The high neutron flux would have to be of thermal neutrons I think, that imposes some severe limitations. As far back as 1986, a flux of thermal neutrons of 10^16 per cm^2 per s was a theoretical possibility. But by 2009, the highest actually achieved in a reactor had no significant improvement since about 1983 and was actually more like 3*10^15 per cm^2 per s.
Is that enough? Yes, or very close to it. At the very least, 10^14 per cm^2 per s would be needed.
For the nuclear blast, fast neutrons, exposure of people was up to somewhere between 250 and 500 Grays. I don’t know offhand how to convert that to a flux. Surround the core with a moderator (such as water) and slower neutrons become a possibility.
For lead-lead collisions we want to start with an isotope with a lot of neutrons like 210Pb with a half life of 22 years. Other options come to mind. Double that and it would be an isotope with 164 protons, way above the 118 protons that is the best created so far.
> is there a theory that explains what has already been observed
I’m not finding the right articles – everything I’ve found so far was written in, for example, 1957.
mollwollfumble said:
> is there a theory that explains what has already been observedI’m not finding the right articles – everything I’ve found so far was written in, for example, 1957.
Perhaps this will help:
“From Heavy to Superheavy nuclei, Systematic Study, A.R.H. Subber and H. Abdul Hassan, 2009”.
Nope, totally empirical, an exercise in curve fitting. Perhaps there isn’t any theory of nuclear physics !
“There are so many ideas about the synthesis of SHN and the most important one which says that the structure of SHN is due to the shell effect. Classically, the best model to be applied on the SHN is the modified Liquid Drop Model which includes the shell correction. Yan et al. used the triaxial projected shell model to find a good application about the vibrational mode in SHN for two Z=100 and Z=102 nuclei.”
I hope I live long enough to see some elements created that are in the 2nd island of stability. Can we predict what properties that they will have? Apart from being rather dense & heavy, of course.
Spiny Norman said:
I hope I live long enough to see some elements created that are in the 2nd island of stability. Can we predict what properties that they will have? Apart from being rather dense & heavy, of course.
Their nucleus will be bigger than normal.
sibeen said:
Spiny Norman said:
I hope I live long enough to see some elements created that are in the 2nd island of stability. Can we predict what properties that they will have? Apart from being rather dense & heavy, of course.
Their nucleus will be bigger than normal.
Oh for sure. But how or what will they react with? How will they accept strong neutron blasts? Can they be integrated with the lesser type of elements that we currently use?
Spiny Norman said:
I hope I live long enough to see some elements created that are in the 2nd island of stability. Can we predict what properties that they will have? Apart from being rather dense & heavy, of course.
Depending on how you define “2nd island of stability” we may already be there. The original definition of second island was for an element near 116 to 118 protons. We’re there, but haven’t been able to give it enough neutrons to stabilise it.
There is a problem in finding an island of stability, too. It’s an annoying truth that the method used to find superheavy elements always relies on their decay products for identification. If we ever find a real stable element up there then we’d never know, because we’ll never be able to observe the decay products.
But now I see that Wikipedia has shifted the “2nd island of stability” up to 164 protons, and 318 neutrons. That’s not the original definition, but comes from a paper in 2008. Lead is element 82, so colliding two of them in a device like the LHC could theoretically give 164 protons, but a maximum of only 264 neutrons, nowhere near enough.
Oh this is funny.
Ages ago I added a wikipedia section called “semi-empirical formula” for binding energy. Wikipedia didn’t have an entry for that before mollwollfumble.
Someone since updated that and moved it to a page on its own. And it’s now considered the best theoretical model for nuclear physics. LOL
mollwollfumble said:
Oh this is funny.Ages ago I added a wikipedia section called “semi-empirical formula” for binding energy. Wikipedia didn’t have an entry for that before mollwollfumble.
Someone since updated that and moved it to a page on its own. And it’s now considered the best theoretical model for nuclear physics. LOL
Congratulations to you and your colleague.
Spiny Norman said:
sibeen said:
Spiny Norman said:
I hope I live long enough to see some elements created that are in the 2nd island of stability. Can we predict what properties that they will have? Apart from being rather dense & heavy, of course.
Their nucleus will be bigger than normal.
Oh for sure. But how or what will they react with? How will they accept strong neutron blasts? Can they be integrated with the lesser type of elements that we currently use?
On the last question, see https://www.sciencealert.com/detailed-simulation-of-worlds-heaviest-oganesson-atom-show-its-weirdness
Even element 118 doesn’t fit in chemically with the periodic table. From the periodic table it ought to be a noble gas. But the electron configuration is computed to be different to all the other noble gases. It may even be a solid.
mollwollfumble said:
Oh this is funny.Ages ago I added a wikipedia section called “semi-empirical formula” for binding energy. Wikipedia didn’t have an entry for that before mollwollfumble.
Someone since updated that and moved it to a page on its own. And it’s now considered the best theoretical model for nuclear physics. LOL
Well done you.
Tau.Neutrino said:
Here’s The Mind-Boggling Reason The Periodic Table Doesn’t Seem to Have an EndAs researchers around the globe race to create the next element on the periodic table – an atom that contains 119 protons – one scientist from Michigan State University is looking into where the table might end.
more…
https://sci-hub.tw/https://www.nature.com/articles/s41567-018-0163-3
The use of ‘hot-fusion’ reactions with neutron-rich 48Ca beams and actinide targets has resulted in measurements of over fifty isotopes of new elements with Z= 114-118 in between 1998 and 2008.
The un-accessed region marked “beta-stable” is what used to be called the second island of stability. This graph is new in that it continues even past N=258.
I see that the gap between the “proton drip line” and “neutron dip line” continues to grow as nuclei get heavier.
“Coming back to Coulomb frustration, one cannot exclude a possibility that there exist isolated islands of nuclear stability, associated with very exotic topologies of nuclear density, stabilized by shell effects. However, it is difficult to say at present whether such exotic topologies can occur as metastable states and what is their stability to various decay modes, especially fission.”
“The pattern of nucleonic shells undergoes significant changes in the superheavy region. The main factors driving these changes are Coulomb frustration effects and the large density of single-particle levels, which grows faster than expected from the A^1/3 scaling. The latter implies that differences in theoretical models can impact the order of nucleonic shells significantly when extrapolating mass and atomic number. From this point of view, it is entirely possible that the nucleus 208Pb is the last ‘proper’ doubly-magic nucleus”.
“Unlike in the case of α-decay, there is no theoretical consensus about spontaneous fission lifetimes of superheavy nuclei. This is because predictions are very sensitive to both input (forces, functionals, treatment of collective inertia) and theoretical framework used. Consequently, theoretical lifetime estimates often differ by many orders of magnitude.”
Um, what is “density functional theory” in this context?
References 19 and 21 seem important.
19. Tolokonnikov, S. V., Borzov, I. N., Kortelainen, M., Lutostansky, Y. S. & Saperstein, E. E. Alpha-decay energies of superheavy nuclei for the Fayans functional. Eur. Phys. J. A53, 33 (2017). 21. Giuliani, S. A., Martnez-Pinedo, G. & Robledo, L. M. Fission properties of superheavy nuclei for r-process calculations. Phys. Rev. C.97, 034323 (2018).Now back to the circling electrons and chemical properties.
“Since atomic relativistic effects scale approximately with Z^2, chemical properties of superheavy atoms cannot be properly described by non-relativistic quantum mechanics. Quantum electrodynamic corrections become substantial. The experimental chemical tests are extremely difficult because one-atom-at-a-time chemistry requires half-lives of the order of 1–2 s and production rates of at least a few atoms per day. There has been major progress in the chemical characterization of transactinides, with the element Fl (Z=114) marking the limit of chemistry today.”
What does Caution No Binding mean?
AwesomeO said:
What does Caution No Binding mean?
Underage girls.
PermeateFree said:
AwesomeO said:
What does Caution No Binding mean?
Underage girls.
IDGI
Could we look for these elements outside of particle colliders and what we’ve created ourselves and look to the universe for example say byproducts of stellar phenomenon
AwesomeO said:
PermeateFree said:
AwesomeO said:
What does Caution No Binding mean?
Underage girls.
IDGI
Not going there.
AwesomeO said:
What does Caution No Binding mean?
I think it is a joke. Above or the below the line the nucleons wont bind. Illustrating it by a caution sign is the joke.
I think.
party_pants said:
AwesomeO said:
What does Caution No Binding mean?
I think it is a joke. Above or the below the line the nucleons wont bind. Illustrating it by a caution sign is the joke.
I think.
Ahh, nerd humour.
I came across this equation. N = 192 tan (0.007(Z-1)). That’s a curve fit to the line of most stable isotopes. If that’s actually true, then the periodic table is limited. The equation crashes when Z >=226.
> The use of ‘hot-fusion’ reactions with neutron-rich 48Ca beams and actinide targets has resulted in measurements of over fifty isotopes of new elements with Z= 114-118 in between 1998 and 2008.
Calcium-48 eh. 20 protons & 28 neutrons makes it doubly magic. Half life near 6*10^19 years.
Next high neutron doubly magic isotope is 28 proton, 50 neutron. What’s that? Nickel-78. Interestingly, Nickel-78 was only confirmed to be doubly magic last year! https://phys.org/news/2017-11-nickel-doubly-magic.html. It has a half life near 110 milliseconds, which would make it too difficult to use. Even nickel-77 has a bigger half life of 300 milliseconds. The take-home-lesson here is that being doubly magic does not guarantee a long half life.
Then 50 proton, 82 neutron. That’s, um, Tin-132. Lifetime 40 seconds. That’s not impossible if it is made on the spot where it is used.
Then 82 proton, 126 neutron – the famous stable Lead 208. See what I said about this above.
OK, rather than limit the search to doubly magic nuclei, what if I look for highest neutron/proton ratio at given half life. I mean with at least 48 protons (so free neutrons and tritium don’t count).
Half life (L) more than 1 day.
Calcium-48, L=10^19 years, N/P=1.4
Iron-60, L=10^6 years, N/P=1.31
Nickel-66, L=54 hours, N/P=1.36
Zinc-72, L=46 hours, N/P=1.4
Germanium-78, L=10^21 years, N/P=1.375
Selenium-82, L=10^20 years, N/P=1.41
party_pants said:
AwesomeO said:
What does Caution No Binding mean?
I think it is a joke. Above or the below the line the nucleons wont bind. Illustrating it by a caution sign is the joke.
I think.
Agree. Yes, nerd humour. Easiest to say that you won’t find any isotopes there.
I came across this equation. N = 192 tan (0.007(Z-1)). That’s a curve fit to the line of most stable isotopes. If that’s actually true, then the periodic table is limited. The equation crashes when Z >=226.
Can/could you artificially stabilise elements say for example with a magnetic field but not just than any sort of method
Cymek said:
I came across this equation. N = 192 tan (0.007(Z-1)). That’s a curve fit to the line of most stable isotopes. If that’s actually true, then the periodic table is limited. The equation crashes when Z >=226.Can/could you artificially stabilise elements say for example with a magnetic field but not just than any sort of method
Some isotopes can be stabilised – it’s rare, but sometimes a higher quantum state can be more stable than the lowest quantum state. The best way to do that is make the isotopes in a way that generates the higher quantum state. The most famous example of a higher quantum state is Technetium-99m, but that’s less stable than the base quantum state of Technetium-99.
Now to look into reference 21. Fission properties of superheavy nuclei for r-process calculations https://arxiv.org/pdf/1704.00554.pdf
Ah, finally, this may be some real theoretical nuclear physics, not the empirical rubbish I put on Wiklipedia.
“The potential energy surfaces and collective inertias of 3640 nuclei in the superheavy region are obtained from Self-Consistent Mean-Field calculations using the Barcelona-Catania-Paris-Madrid energy density functional. We start defining the fission tunneling probability …”
Not much sign of an island of stability there. Higher contour numbers are more stable against spontaneous fission. Between the dashed and dash-dotted lines is more stable with respect to beta decay and inverse beta decay.
The best chance for an island of stability then would be near 100 protons and 220 neutrons … nope … reading further, that’s below the r-process path so could never be made. Nearly everything above the r-process path is unstable.
Oops. I was wrong in my understanding of beta decay.
> The best chance for an island of stability then would be near 100 protons and 220 neutrons … nope … reading further, that’s below the r-process path so could never be made. Nearly everything above the r-process path is unstable.
Trying another source of information, wikipedia, “120 protons and 180 neutrons”. Compare with chart above and chart below.
Trying another source of information Yuri Oganessian “Nuclei in the “Island of Stability” of Superheavy Elements”
http://iopscience.iop.org/article/10.1088/1742-6596/337/1/012005/pdf
This article is written for the non-specialist, is very easy to read, and is well worth a read. It is more a historically important document than a highly accurate one. This is the leader of the successful Russian search for superheavy elements.
Here Oganessian predicted first island centred at 106 protons 162 neutrons.
And second island centred at 110 protons and 180 neutrons.
“In 1962, in our Laboratory in Dubna,
an unexpected effect was observed, which
caused great doubts in the analogy of nuclear
fission and a liquid drop. The isotope of 242Am,
obtained in a nuclear reaction, experienced
spontaneous fission with two, very different
half-lives: 10^14 yr, and 0.014 s. Subsequently,
a similar phenomenon was observed in more
than 31 nuclei with Z = 92-97. Definitely,
fission in these nuclei occurs from two states -
the ground and isomeric states.”
This is what I referred to above for Technetium=99m, same isotope but multiple quantum states.
“Neutron-rich superheavy nuclei can in principle be synthesized if the heaviest actinides: 244Pu, 243Am,
248Cm, 249Bk and 251Cf, obtained in powerful nuclear reactors, were used as targets. As the projectile, we
have chosen the rare isotope of calcium with mass number 48. As a result of two years work using an
ECR-source and the U-400 accelerator, a stable beam of 48Ca ions was obtained with high intensity. 10^12 to
10^13 particles per second. This allowed conducting long-term experiments (6000 hours/year) over the past 10
years. The registration of rare events of formation and decay of superheavy atoms was performed by
a gas-filled recoil separator.”
The figure below is a prediction of the original second island of stability (with respect to spontaneous fission) near Z=112, N=184.
> Now to look into reference 21. Fission properties of superheavy nuclei for r-process calculations https://arxiv.org/pdf/1704.00554.pdf . Ah, finally, this may be some real theoretical nuclear physics, not the empirical rubbish I put on Wikipedia.
All six theoretical (including two semi-empirical) models of atomic nuclei get the half life of uranium (all isotopes) and thorium wrong.
How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49. A decillion is only 10^33.
And quantum mechanics is frequently called “The Most Precisely Tested Theory in the History of Science”.
Yeah, right.
mollwollfumble said:
> Now to look into reference 21. Fission properties of superheavy nuclei for r-process calculations https://arxiv.org/pdf/1704.00554.pdf . Ah, finally, this may be some real theoretical nuclear physics, not the empirical rubbish I put on Wikipedia.All six theoretical (including two semi-empirical) models of atomic nuclei get the half life of uranium (all isotopes) and thorium wrong.
How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49. A decillion is only 10^33.
And quantum mechanics is frequently called “The Most Precisely Tested Theory in the History of Science”.
Yeah, right.
https://www.quora.com/Why-is-quantum-mechanics-called-the-most-precisely-tested-theory-in-the-history-of-science-when-its-predictions-are-inherently-based-on-probabilities-due-to-the-uncertainty-principle-Is-it-purely-statistical-precision
ChrispenEvan said:
mollwollfumble said:
> Now to look into reference 21. Fission properties of superheavy nuclei for r-process calculations https://arxiv.org/pdf/1704.00554.pdf . Ah, finally, this may be some real theoretical nuclear physics, not the empirical rubbish I put on Wikipedia.All six theoretical (including two semi-empirical) models of atomic nuclei get the half life of uranium (all isotopes) and thorium wrong.
How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49. A decillion is only 10^33.
And quantum mechanics is frequently called “The Most Precisely Tested Theory in the History of Science”.
Yeah, right.
https://www.quora.com/Why-is-quantum-mechanics-called-the-most-precisely-tested-theory-in-the-history-of-science-when-its-predictions-are-inherently-based-on-probabilities-due-to-the-uncertainty-principle-Is-it-purely-statistical-precision
https://en.wikipedia.org/wiki/Precision_tests_of_QED
ChrispenEvan said:
ChrispenEvan said:
mollwollfumble said:
> Now to look into reference 21. Fission properties of superheavy nuclei for r-process calculations https://arxiv.org/pdf/1704.00554.pdf . Ah, finally, this may be some real theoretical nuclear physics, not the empirical rubbish I put on Wikipedia.All six theoretical (including two semi-empirical) models of atomic nuclei get the half life of uranium (all isotopes) and thorium wrong.
How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49. A decillion is only 10^33.
And quantum mechanics is frequently called “The Most Precisely Tested Theory in the History of Science”.
Yeah, right.
https://www.quora.com/Why-is-quantum-mechanics-called-the-most-precisely-tested-theory-in-the-history-of-science-when-its-predictions-are-inherently-based-on-probabilities-due-to-the-uncertainty-principle-Is-it-purely-statistical-precision
https://en.wikipedia.org/wiki/Precision_tests_of_QED
I note that prediction of isotope half lives is not among them.
mollwollfumble said:
ChrispenEvan said:
ChrispenEvan said:https://www.quora.com/Why-is-quantum-mechanics-called-the-most-precisely-tested-theory-in-the-history-of-science-when-its-predictions-are-inherently-based-on-probabilities-due-to-the-uncertainty-principle-Is-it-purely-statistical-precision
https://en.wikipedia.org/wiki/Precision_tests_of_QED
I note that prediction of isotope half lives is not among them.
so? that is statistical surely.
> How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49
The ratio of the diameter of the observable universe to the radius of the nucleus of a hydrogen atom is still only 10^42. So the magnitude of the error is twenty million times that.
mollwollfumble said:
> How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49The ratio of the diameter of the observable universe to the radius of the nucleus of a hydrogen atom is still only 10^42. So the magnitude of the error is twenty million times that.
Back to the blackboard.
Michael V said:
mollwollfumble said:
> How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49The ratio of the diameter of the observable universe to the radius of the nucleus of a hydrogen atom is still only 10^42. So the magnitude of the error is twenty million times that.
Back to the blackboard.
At least an engineer is generally only out by one order of magnitude :)
sibeen said:
Michael V said:
mollwollfumble said:
> How wrong? The closest of the six theoretical models for the half life of thorium-232 gets the half life wrong by a factor of 100,000,000,000, a hundred billion. The furthest of the six theoretical models gets it wrong by a factor of 10^49The ratio of the diameter of the observable universe to the radius of the nucleus of a hydrogen atom is still only 10^42. So the magnitude of the error is twenty million times that.
Back to the blackboard.
At least an engineer is generally only out by one order of magnitude :)
Heh.
