Comments on: Welcome to the table, Ununbium

By: physicsguy

physicsguy — Sun, 14 Jun 2009 12:36:09 +0000

Occam, the comment about elevating theory over observation is very important…. look what it’s got us into with respect to “global warming”.

Also, the comment that QM provides the ‘why’ of the Table is also right on… I’m just a bit awed with that ‘why’ on a daily basis 😉

However, I’m also eagerly awaiting the marriage of QM and Gen. Rel. which I think will have tremendous implications, OR a new theory which incorporates both in a completely new paradigm. That’s what makes science fun.

By: Occam's Beard

Occam's Beard — Sat, 13 Jun 2009 16:38:11 +0000

Physicsguy, I’d turn it the other way around, myself, particularly since Mendeleev antedated Pauli by 60 years, and say that the Periodic Table helped to stimulate and guide the development of quantum mechanics by raising the question of why the table had the structure it did.

Clearly there was some principle underlying the table that needed to be discovered and understood.
The Aufbau principle explained why, e.g., there were only eight elements in the short periods.

So I’d say the quantum mechanics provided an explanation for why the Periodic Table has its structure.

Also, it’s important not to elevate theory over observation. If quantum mechanics should fall tomorrow (don’t laugh – Newtonian mechanics did!), any new theory will still have to explain the observed periodicity of elemental properties that Mendeleev systematized in his table.

By: Gringo

Gringo — Sat, 13 Jun 2009 13:34:14 +0000

This discussion is reminding me of how much I have forgotten since my undergraduate days, especially considering the amount of chemistry I took.

By: physicsguy

physicsguy — Sat, 13 Jun 2009 12:55:49 +0000

I actually think the best discovery is that of Pauli and his exclusion prinicple. Without that, the Periodic Table loses its structure. Deep down, that chart on the wall really means no two spin-1/2 particles can ever occupy the same state.

That said, I really do appreciate the intellecual tour-du-force that Mendeleev accomplished without the backing theory of Quantum Mechanics to help him along.

By: neo-neocon

neo-neocon — Sat, 13 Jun 2009 04:25:17 +0000

Occam’s Beard: I’m with you on that. As I wrote in the essay, ever since I learned the way the Periodic Table worked I’ve thought it’s one of the most awesome things in the universe.

By: Occam's Beard

Occam's Beard — Sat, 13 Jun 2009 01:52:23 +0000

As a chemist, I consider the Periodic Table to be probably the single most important breakthrough in the subject, because it systematized chemistry. The Periodic Table provided a conceptual framework to understand, think about, and even predict what superficially appeared to be wildly disparate observations.

I used to ask prospective students what discovery they would want to have made. Most said the structure of DNA, but for my money, it’d be the Periodic Table. Imagine how Mendeleev must have felt when he saw the pattern, or how Moseley (who, critically, shifted the ordering principle from atomic weight to atomic number) when he realized that he’d just explained why it worked! Magical.

By: Good Ole Charlie

Good Ole Charlie — Sat, 13 Jun 2009 00:54:48 +0000

I do teach AP Chem and Honors Chem, in addition to plain vanilla Chemistry.
The explanation of the Periodic Table is a triumph for quantum mechanics…so the level of sophistication depends on the course.
AP Chem gets the full treatment, ending with a derivation of the molecular orbitals of simple diatomic molecules…pre calculus is handy. Nothing to be unlearned later.
Honors gets the same basic treatment, stopping with hybrid orbitals and VSEPR. They are bright enough, but lack the math background to sweat the mathematical details.
Chemistry has to settle for a “Take my word for it” treatment. Gross similarities and trends in the rows and groups are the best I can expect, although they try to learn about electrons in bonding.
I do NOT make students memorize the names and symbols of elements. To do so is the sign of a lazy teacher whose knowledge ended a few decades ago. Students can always consult a periodic table when in doubt…that’s what she’s for.

By: neo-neocon

neo-neocon — Fri, 12 Jun 2009 23:32:23 +0000

Gringo: Here's an old post of mine about Tom Lehrer. It contains, among other things, a little anecdote about how the song "The Elements" once came in very handy for me.

By: Gringo

Gringo — Fri, 12 Jun 2009 23:16:47 +0000

Here is an animated version of Tom Lehrer’s Elements Song. With a bow to Gilbert and Sullivan, of course.

Perhaps Mr. Lehrer will put out a new version of the song in accordance with what news has come to Harvard and other places.

http://www.youtube.com/watch?v=zGM-wSKFBpo

By: jon baker

jon baker — Fri, 12 Jun 2009 21:48:33 +0000

“planets” not “plantes” and “electron”, not “elctrons” I really need to start proof reading better. I scan, reading words often based on the first letters, and miss my many typos.