
The seventh row of the periodic table is now full - srikar
http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html
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NelsonMinar
See also the hypothetical Island of Stability.
[https://en.wikipedia.org/wiki/Island_of_stability](https://en.wikipedia.org/wiki/Island_of_stability)

~~~
NelsonMinar
One of the scientists working on these elements commented on the Island of
Stability on Reddit. "While the next "magic" number of protons is predicted to
be 114, 120 or 126, we are still too far away from the next extra stable
configuration of neutrons."

[https://www.reddit.com/r/science/comments/400w7k/science_ama...](https://www.reddit.com/r/science/comments/400w7k/science_ama_series_im_dawn_shaughnessy_from_the/cyqu7or)

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mikemaccana
Here's the current full table (with the seventh row complete):

[https://upload.wikimedia.org/wikipedia/commons/3/3d/Discover...](https://upload.wikimedia.org/wikipedia/commons/3/3d/Discovery_of_chemical_elements.svg)

~~~
JumpCrisscross
Why are elements 57 and 89 shaded white?

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gnoway
Those are placeholders for the two rows (lanthanide and actinide series) below
the main table.

~~~
derefr
To be clear—it's because the periodic table is actually shaped like this:
[http://www.chemistryland.com/CHM130W/03-BuildingBlocks/Chaos...](http://www.chemistryland.com/CHM130W/03-BuildingBlocks/Chaos/PeriodicInnerTrans.jpg)

I think folding the periodic table like we do makes it much harder for
children to understand valence levels. To quote Wikipedia
([https://en.wikipedia.org/wiki/Atomic_orbital](https://en.wikipedia.org/wiki/Atomic_orbital)):

> The "periodic" nature of the filling of orbitals, as well as emergence of
> the s, p, d and f "blocks", is more obvious if this order of filling is
> given in matrix form, with increasing principal quantum numbers starting the
> new rows ("periods") in the matrix. Then, each subshell (composed of the
> first two quantum numbers) is repeated as many times as required for each
> pair of electrons it may contain. The result is a compressed periodic table,
> with each entry representing two successive elements:
    
    
       1s
       2s                                                  2p  2p  2p
       3s                                                  3p  3p  3p
       4s                              3d  3d  3d  3d  3d  4p  4p  4p
       5s                              4d  4d  4d  4d  4d  5p  5p  5p
       6s  4f  4f  4f  4f  4f  4f  4f  5d  5d  5d  5d  5d  6p  6p  6p
       7s  5f  5f  5f  5f  5f  5f  5f  6d  6d  6d  6d  6d  7p  7p  7p
    

_That 's_ a table that lets you _understand_ things.

\---

...though, taking it absurdly literally, imagine a world where our taxonomy of
"elements" was constructed like this, rather than by proton-counting. Hydrogen
and Helium would be different isotopes (prototopes?) of the same element.
Fluorine and Neon would be the same "element", too. We'd get a strong
intuitive sense, even from first hearing about chemicals as children, that
certain "elements" have volatile behaviors that can be explained by what
they're paired with—Fluorine being so reactive because it's the -1 "prototope"
of Neon and really wants to oxidize something so it can have Neon's full
valence shell, etc.

Or, to go further, imagine we divided our chemical taxonomy by _entire
subshell_ —that we just had elements called "1s", "4f", etc. with "prototopes"
for uranium, actinium, etc., with their distance from an empty/full subshell
represented in their names. It'd be immediately clear what makes certain
elements semiconductors: silicon's name would be "3p±4" and, well, that's all
you need to know about silicon.

~~~
s_henry_paulson
I think some would say that the "actual" shape (and possibly easier to learn)
is more of a spiral than a table format.

[http://i.imgur.com/QOoKC1a.jpg](http://i.imgur.com/QOoKC1a.jpg)

~~~
dietrichepp
The periodic table is a human construct, so its "actual shape" is not in
dispute.

(And why is iron below helium, neon, and argon? That makes no sense at all.)

~~~
jacquesm
That may be true, but even models can have a closer or less close relationship
to the thing they model and modeling 3D orbits around a central nucleus is
quite hard in a rectangular mapping, the spiral (even if this one may be
flawed) seems to show more clearly that the space in orbits further out will
accommodate more electrons.

~~~
dietrichepp
What do you mean by "modeling 3D orbits"? Because that's not what the periodic
table is doing. It's telling you which quantum numbers are in use. The
rectangle is extremely good at that (with a couple minor simplifications). The
problem with the spiral is that it will have the same discontinuities as the
rectangle, because each angular momentum number has two more magnetic quantum
numbers than the previous.

Or, in other words, the disadvantage of putting more space farther out is that
you lose the most important property of the periodic table, which is the
groups.

~~~
jacquesm
2n^2, that the underlying reason for that equation is a quantum effect is not
required for the basic understanding that 'further out' means 'more room'.
That in the end the equations are about energy levels rather than space does
not matter when you're trying to remember what the periodic table looks like,
it's a useful mental construct, even if it is fundamentally in-accurate.

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jacquesm
What are the chances of any more non-radio active elements to be found? Is the
current knowledge sufficient to state this will never happen or is there still
a very small chance?

~~~
ajuc
[https://en.wikipedia.org/wiki/Island_of_stability](https://en.wikipedia.org/wiki/Island_of_stability)

> Although predictions of the exact location differ somewhat, Klaus Blaum
> expects the island of stability to occur in the region near the isotope
> 300Ubn.

> Estimates about the amount of stability on the island are usually around a
> half-life of minutes or days, with "some optimists" expecting half-lives of
> millions of years.

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majke
Element 115 just _must_ be called Elerium!

[http://www.ufopaedia.org/index.php?title=Elerium-115](http://www.ufopaedia.org/index.php?title=Elerium-115)

~~~
rspeer
In other names that are unlikely to happen, ununoctium would be a pretty good
candidate to be named "unobtainium".

Qualifications include the kind of similar name, its half-life of less than a
millisecond, and the bizarre properties it's hypothesized to have if you
somehow put enough of it together to have physical properties.

~~~
rdancer
Isn't that about on the level of calling an actual piece of software "Foobar"?

~~~
Kortaggio
That piece of software exists, it's a popular audio player called foobar2000
[https://www.foobar2000.org/](https://www.foobar2000.org/)

~~~
rdancer
That's why I asked that. Their's a crap name.

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troels
What's the in-joke with the temporary names? (ununtrium, ununpentium ...)

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Macha
Pretty sure they're just sort-of-latin for 113-ium, 115-ium etc.

~~~
troels
I was mostly thinking of the unun part?

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pdpi
One is "unum" in latin.

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troels
Thanks, that was what I was missing. I figured it was the un- prefix, which
means something like non-existing.
([https://en.wiktionary.org/wiki/un-#Prefix](https://en.wiktionary.org/wiki/un-#Prefix))

