
The periodic table is 150 years old this week - jkuria
https://www.economist.com/science-and-technology/2019/02/28/the-periodic-table-is-150-years-old-this-week
======
apo
One of the most interesting controversies I've seen about periodic table
schemes is the placement of helium. It usually sits above neon as a noble gas.
However, not everyone agrees with that:

 _" Two things are surprising about Mendeleev’s classification of the chemical
elements according to the Periodic Law,” Bent writes. “One is how much of the
classification has not needed revision. The other is how long the scheme’s
second element has been misplaced, above neon, despite Mendeleev’s Rule of
Light-Element Distinctiveness; despite his statement that the Periodic System
is about atoms, not simple substances; despite classification by atomic
physics of helium atoms as s2 systems (not p6 systems); despite appearance of
the Left-Step Periodic Table nearly eight [now over nine] decades ago; and
despite numerous implications of the LSPT that require placement of helium
above beryllium.”_

[https://cen.acs.org/unassigned/Reactions/97/i3](https://cen.acs.org/unassigned/Reactions/97/i3)

How you view the placement of helium (and other more difficult elements) comes
down to what you believe the table represents:

\- empirically-derived reactive trends of elemental substances (in which case
helium above neon makes much more sense); or

\- a summary of theoretically-derived electronic configuration (in which case
helium above beryllium makes perfect sense).

You can see aspects of both views in the modern canonical table. It's weird
exceptional cases like this that can, among other things, make chemistry such
a difficult (and fun) subject to learn.

~~~
trophycase
Why does electronic configuration put it above Beryllium? Helium has a full
first shell of electrons, and other noble gases have their subsequent shells
filled with electrons, this is why they all have their property of being more
or less inert. The reactive trends of noble gases aren't "emperically derived"
as you say but as a result of being extremely energetically stable due to
having full electron orbital shells.

EDIT: Perhaps I misunderstood and you meant that its initial placement was due
to empirical data. But for good theoretical reason it has remained where it is
IMO.

~~~
gus_massa
Beryllium has 2 electrons and 6 holes in the last shell.

Neon has 8 electrons and 0 holes in the last shell.

Helium has 2 electrons and 0 holes in the last shell.

How do you align Helium, in the 2 electrons column over Beryllium or in the 0
holes column over Neon?

[I vote for aligning it over Neon.]

~~~
trophycase
If the number of holes tells you more about the reactivity and properties of
the element than the number of electrons in the outermost shell, then they
should be arranged that way. AFAIK there is no theoretical mandate that the
periodic table should be the way that it is, so just organize it in the way
that makes sense while also providing maximum utility.

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cr0sh
It's things like this that should serve as good reminders just how young our
"modern existence" is, how far we've come as a species in such a short time,
and (potentially) how easy it could all slip away if we let it.

Maybe that's not the best way to put it, but I hope my point comes across
anyhow...

Happy Birthday, Periodic Table. May you have 150+ more...

~~~
throway88989898
> reminder

Time
[https://www.youtube.com/watch?v=2XkV6IpV2Y0](https://www.youtube.com/watch?v=2XkV6IpV2Y0)

Space
[https://www.youtube.com/watch?v=0fKBhvDjuy0](https://www.youtube.com/watch?v=0fKBhvDjuy0)

It's like asking a 2 year old to count way... way past 10

~~~
amelius
(They should make a similar movie about wealth distribution, going from
someone who makes 1 dollar a month up until Jeff Bezos.)

~~~
hjk05
Look up dollar street by the same people who made gap minder. It’s a
wonderfully simple look into the differences in wealth and living, which shows
you things like “favorite thing” filtered along an axis of wealth.

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pradn
There are now attempts to create a "periodic table" for data structures. Such
a table would allow you to predict variations of data structures and the
behavior of such variants. You can see such an example in page 7 of the PDF
below.

[https://stratos.seas.harvard.edu/files/stratos/files/periodi...](https://stratos.seas.harvard.edu/files/stratos/files/periodictabledatastructures.pdf)

~~~
iaabtpbtpnn
I'm very interested to read this paper, but the grammar mistake in the first
sentence of the first section doesn't bode well...

~~~
killaken2000
Is it the is/are issue?

Maybe they are using it as a mass noun or speaking specifically about the the
phrase itself or the idea of data structures. Could stem from a cultural or
ESOL reason.

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lkbm
I'm pretty under-educated on chemistry, but I read Asimov's _Search For The
Elements_ a few years ago and loved it. It really demystified things.

In modern times it's easy for laymen to just wave our hands and say "yeah, we
use fancy technology to do this stuff, which pretty much just treats it as
magic. Asimov goes through the development of the periodic table and the
discover of individual elements using classic technology.

Scanning tunneling microscope is still opaquely magic in my brain, but reading
about discovering an element using technology I already understand makes even
modern chemistry feel more in the realm of stuff I can get a solid grip on.

~~~
xkcd-sucks
So I actually did a PhD in chemistry and just happen to work in software for
reasons [0]. A thing that totally blows my mind about the periodic table and
early materials chemistry is how it's in essence a derivation of "quantum
mechanical" electronic structure.

One which was achieved through top-down "black box" debugging of nature on a
scale too small for any human to see or touch!

[0]
[https://news.ycombinator.com/item?id=19266614](https://news.ycombinator.com/item?id=19266614)

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exochrono
Highly recommend reading Oliver Sacks' Uncle Tungsten - his tale of growing up
and discovering the beauty of the periodic table with his home chemistry set.
Made me appreciate chemistry and the periodic table and Oliver Sacks so much
more.

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wwarner
I think the coolest thing about the periodic table is that it's macroscopic
evidence of the discrete, particle nature of atoms and the rest of the sub-
atomic universe.

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readhn
Quote from Mendeleev himself:

"I saw in a dream a table where all the elements fell into place as required.
Awakening, I immediately wrote it down on a piece of paper."

This is fascinating to me -- Our brains continue working during our sleep on
problems we think about during our day!

~~~
cheerlessbog
The structure of Benzene was famously conceived in the same way.

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richardhod
Here's a bunch of other interesting subsequent designs
[https://en.m.wikipedia.org/wiki/Alternative_periodic_tables](https://en.m.wikipedia.org/wiki/Alternative_periodic_tables)

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doggydogs94
In the last fifty years or so, 15 elements have been added to the periodic
table.

~~~
ekun
I went to a talk at Oak Ridge National Lab soon after the discovery of
Ununseptium (element 117 that is now called Tennessine) and it was really
interesting the international collaboration needed to make the discovery
happen.

Basically, at Oak Ridge they produced radioactive isotopes with the
appropriate number of neutrons and protons to match the theoretical ratio of
the atom. Then, those isotopes needed to be shipped to Russia so they could be
smashed together in a particle accelerator to briefly create the atom which we
know existed from its specific decay and gamma ray emission.

But there was a lot of political hurdles in the way of shipping the isotopes
to Russia in the first place, and it almost didn't happen because the isotopes
were decaying while paperwork was floundering between state departments.

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acqq
The accessible (no registration/subscription required) article:

[https://www.newscientist.com/article/mg24132190-300-the-
true...](https://www.newscientist.com/article/mg24132190-300-the-true-story-
of-the-birth-of-the-periodic-table-150-years-ago/)

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dsteinman
One of the best documentaries I've seen on the subject is BBC's A Volatile
History : [https://youtu.be/g_2bo4abkPI](https://youtu.be/g_2bo4abkPI)

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tonymet
Mendeleevs Table

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Isamu
Hey, to celebrate this, everybody share your favorite "Periodic Table of X"
where X is something that is absolutely not periodic at all!

~~~
andrewflnr
The Periodic Table of Things Not On Any So-Called "Periodic Table of X".

~~~
chowells
Does it contain itself?

~~~
ordu
Periodic table of self?

