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Einstein's relativity rules chemical bonds in heavy elements, new research shows

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Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#161

Post by gweinberg »

Laforet wrote: post #134
sigmoid10 wrote: post #124

Earlier quoted context omitted.

I guess the more interesting question is why this doesn't happen for neighbouring elements in the periodic table?

Relativistic effects are observed with many other 6th and 7th period elements. For example, the yellow colour of gold and caesium comes from altered electron energy levels due to relativistic orbital contraction, so are the special catalytic and bonding properties of platinum. https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry

OP claimed relativistic effects explain why mercury is liquid at room temperature. That may be part of the story, but it isn't the whole thing, since other heavy elements are not liquid at room temperature.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#162

Post by gigatexal »

gcanyon wrote: post #123

> The increased nuclear mass causes orbiting electrons to speed up to a significant fraction of the speed of light, where the rules of Einstein’s theory of relativity are important. Fun fact: this is why mercury is liquid at room temperature. Its inner electrons move at close to 60% the speed of light, pulling in its outer electrons more tightly, making it harder for it to bond and be solid. (I am not a physicist, do…

This is the coolest fact I’ve learned in a long time. Thank you!

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#163

Post by ChrisClark »

prox wrote: post #160
moelf wrote: post #154

Earlier quoted context omitted.

well, 90%+ of the mass of a proton comes from moving stuff, rather than rest mass of the quarks. so the real world impact is, having anything at all

I think I recently learned that the Higgs is actually not that much part of imparting mass for atomic particles. I thought it imparted all mass.

just enough to keep electrons from staying at light speed like photons

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#164

Post by colechristensen »

alok-g wrote: post #155
colechristensen wrote: post #39

Earlier quoted context omitted.

The Dirac equation which is the equation for describing the wavelike behavior of electrons. It predicted the existence of antimatter and particle spin. You start with the Schrödinger equation, add relativity to get the Klein-Gordon equation which is a mess because it's second order in time involving negative probabilities, if you in ways "take the square root" of it you get the Dirac equation. Relativity has been par…

Thanks for the insights. I am interested in learning all this stuff. Am currently going through just Schrodinger's Equation. Do you have book recommendation(s) that include insights everywhere just like what you shared? Thanks.

These are books to train physicists, accessable-ish to a math heavy engineering undergraduate degree holder. The insights above are my own and extractable from this material but not necessarily stated out loud (unless I'm unconsciously plagiarizing which is entirely possible)

* David Griffiths - Introduction to Elementary Particles

* Chris Quigg - Gauge Theories of the Strong, Weak, and Electromagnetic Interactions

And the wonderful Richard Behiel's videos on YouTube https://www.youtube.com/watch?v=8Iu74b5iCuQ

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#165

Post by [deleted] »

marcosdumay wrote: post #18
nomel wrote: post #7

Earlier quoted context omitted.

I had incredible difficulties with Chemistry, more than any other subject, because most everything was hand waved away, requiring mostly rote memorization. I could never get an intuitive understanding, partly because my profs seemingly refusing to think about things from a physics perspective. My physics prof was able to help with some of it. It was very odd. If I would have stuck with it, would things have improved?

The physics that predicts chemistry is about 100 years old. Almost nothing people study up to high-school is that recent, and that modern physics tends to be really hard.

[deleted]

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#166

Post by zweifuss »

JumpCrisscross wrote: post #21
marcosdumay wrote: post #18

Earlier quoted context omitted.

The physics that predicts chemistry is about 100 years old. Almost nothing people study up to high-school is that recent, and that modern physics tends to be really hard.

> physics that predicts chemistry Do we have this?

As said before, the physics for chemistry is 100 years old (Schrödinger/Dirac), but the N-body Hamiltonian is an exponential beast. Scaling to just 1mg (~10¹⁹ particles) hits the "Exponential Wall."

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#167

Post by nyrikki »

gweinberg wrote: post #161
Laforet wrote: post #134

Earlier quoted context omitted.

Relativistic effects are observed with many other 6th and 7th period elements. For example, the yellow colour of gold and caesium comes from altered electron energy levels due to relativistic orbital contraction, so are the special catalytic and bonding properties of platinum. https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry

OP claimed relativistic effects explain why mercury is liquid at room temperature. That may be part of the story, but it isn't the whole thing, since other heavy elements are not liquid at room temperature.

Explaining relativistic effects in plain text forums to a general audience is a big ask, but here is a link to the first study[0] that gave evidence but it has long expected.

[0] https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.201302...

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#168

Post by dboreham »

nomel wrote: post #7
aaaronic wrote: post #5

Earlier quoted context omitted.

Sigma and Pi bonds are typically covered in AP Chemistry, even if the “why/how” is hand waved pretty heavily. The valence cloud shapes get wild for heavier atoms and bonds between two or more atoms add even more to the mix.

I had incredible difficulties with Chemistry, more than any other subject, because most everything was hand waved away, requiring mostly rote memorization. I could never get an intuitive understanding, partly because my profs seemingly refusing to think about things from a physics perspective. My physics prof was able to help with some of it. It was very odd. If I would have stuck with it, would things have improved?

The waving, and the resulting need to memorize a zillion special cases, put me off Chemistry for life.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#170

Post by gmueckl »

dolni wrote: post #152
gmueckl wrote: post #68

Earlier quoted context omitted.

Where is physics chock full pf exceptions?

I'm not a physicist but I've always seen physics as a bit hand-wavy myself. Dark matter is a great example. Our understanding of gravitation didn't cleanly apply at ultra-large scales so we had to add a massive fudge factor. You can't "go faster" than the speed of light, but space in between things can expand faster than the speed of light. It seems like things that are "settled" regularly get an "ope, but except for…

There is no handwaving involved. The layman explanations of these phenomena are not that good. The quantitative derivations that leads to those results are totally fine, but hard to follow without deep knowledge of the subject.

Physics education sometimes aligns with historical evolution of the theories, mostly because that builds intuition and because the mathematical founsations of the improved theories need to be taught first. That leads to the "but in this case..." moments, but you need to realize that what you get taught as a "fix" is practically always a careful evolution that also reproduces all predictions from the less complete earlier theory.

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