HomeLatest ThreadsGreatest ThreadsForums & GroupsMy SubscriptionsMy Posts
DU Home » Latest Threads » Forums & Groups » Main » Editorials & Other Articles (Forum) » The seventh row of the pe...

Sun Jan 3, 2016, 09:09 AM

 

The seventh row of the periodic table is officially full.



On December 30, the International Union of Pure and Applied Chemistry announced that a Russian-U.S. collaboration had attained sufficient evidence to claim the discovery of elements 115, 117 and 118. IUPAC awarded credit for the discovery of element 113 to scientists at RIKEN in Wako, Japan (SN Online: 9/27/12). Both groups synthesized the elements by slamming lighter nuclei into each other and tracking the decay of the radioactive superheavy elements that followed.

Researchers at the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in California, which are among the institutions credited with elements 115, 117 and 118, had also laid claim to element 113 after experiments in 2004 (SN: 2/7/04, p. 84) and 2007. But garnering recognition for the three other elements softened the blow, says Dawn Shaughnessy, who leads the experimental nuclear and radiochemistry group at Livermore. ďIím personally very happy with IUPACís decision,Ē she says.

Published reports on the newly recognized elements will appear in early 2016, says IUPAC executive director Lynn Soby. Official recognition of the elements means that their discoverers earn the right to suggest names and symbols. Element 113 will be the first element discovered and named by researchers in Asia.


https://www.sciencenews.org/article/four-elements-earn-permanent-seats-periodic-table

9 replies, 2104 views

Reply to this thread

Back to top Alert abuse

Always highlight: 10 newest replies | Replies posted after I mark a forum
Replies to this discussion thread
Arrow 9 replies Author Time Post
Reply The seventh row of the periodic table is officially full. (Original post)
Proserpina Jan 2016 OP
lastlib Jan 2016 #1
mindwalker_i Jan 2016 #2
Proserpina Jan 2016 #3
mindwalker_i Jan 2016 #4
Proserpina Jan 2016 #5
muriel_volestrangler Jan 2016 #7
eppur_se_muova Jan 2016 #8
Festivito Jan 2016 #6
eppur_se_muova Jan 2016 #9

Response to Proserpina (Original post)

Sun Jan 3, 2016, 12:50 PM

1. Sure glad we have these people playing with subatomic particles,

and not Sarah Palin! . . .

Reply to this post

Back to top Alert abuse Link here Permalink


Response to Proserpina (Original post)

Sun Jan 3, 2016, 01:21 PM

2. That begs the question...

What will elements be like when more electrons start filling the next shell? I imagine there will be some crazy orbitals.

Reply to this post

Back to top Alert abuse Link here Permalink


Response to mindwalker_i (Reply #2)

Sun Jan 3, 2016, 01:29 PM

3. I'm not convinced it's possible, under quantum mechanics

 

to create a real element at a higher shell level than the rare earths. At some point, quantum mechanics cannot support any more and Newton's mechanics take over...

Reply to this post

Back to top Alert abuse Link here Permalink


Response to Proserpina (Reply #3)

Sun Jan 3, 2016, 02:47 PM

4. That's possibly the case

I wonder how far out the orbitals would be, and whether that forces the electrons to behave classically. It might be an interesting case in between quantum and classical, which would make it extremely useful to study. However, the energy required for the electron to escape the nucleus might be very small, on the order of thermal energy.

Reply to this post

Back to top Alert abuse Link here Permalink


Response to mindwalker_i (Reply #4)

Sun Jan 3, 2016, 03:25 PM

5. The discussion indicates two problems with larger atoms

 

The first is stability of the nucleus of any larger size. The second is the ability to hold stable another electron in a new shell. Interesting idea of a kind of tandem-nuclei, two strongly stable nuclei (apparently there are certain configurations that are better at holding together than most) in a stable bond that creates a "double-strength" nucleus....

quantum physics is only a hobby for me...I claim no expertise.

Reply to this post

Back to top Alert abuse Link here Permalink


Response to Proserpina (Reply #5)

Mon Jan 4, 2016, 06:28 AM

7. Some physicists put the hoped-for 'island of stability' at atomic number 120

https://en.wikipedia.org/wiki/Island_of_stability

which would be the next element down from radium in the table.

Reply to this post

Back to top Alert abuse Link here Permalink


Response to Proserpina (Reply #3)

Mon Jan 4, 2016, 06:16 PM

8. Ummmm no, nothing wrong with QM in that sense ...

there is, however, a real question whether any nucleus larger than Z=137 can exist. The electric field gradient is so steep at a nucleus of that charge that positron-electron pairs could be created spontaneously with no further input of energy. The electron would then be absorbed by the nucleus and the positron ejected at high velocity. Thus any nucleus beyond Z=137 is likely to decompose immediately on creation, having no finite lifetime at all.

Some interesting effects do arise because of relativity in such high-Z atoms; in fact there was some debate over whether the 7p orbitals would fill up normally because the energy of spin-alpha and spin-beta electrons is not the same under a fully relativistic treatment, although this is ingnored in most chemistry textbooks. By the time the seventh row was reached, there was a very real possibility that, say, the p-alpha orbitals would be filled, but the p-beta would be higher in energy than the 8s-alpha (I'm not using the standard relativistic notation, which is too unfamiliar even to chemists), so that the row would 'break' in a different location. This promises to make assignments of orbitals for heavier atoms problematic; from a chemist's point of view, we may have run out of stable nuclei just barely in time.

While it's true that some properties of atoms with electrons in very high quantum number orbitals do approach their classical properties, QM is still needed to model them properly -- see Rydberg Atoms.

Reply to this post

Back to top Alert abuse Link here Permalink


Response to Proserpina (Original post)

Sun Jan 3, 2016, 04:16 PM

6. Finished being mindful of their p's and U's.

Reply to this post

Back to top Alert abuse Link here Permalink


Reply to this thread