Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

brown.edu

Post reply on HN
Print view View original

21–30 of 207 posts

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

#21

Post by JumpCrisscross »

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.

> physics that predicts chemistry

Do we have this?

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

#22

Post by asdff »

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?

Not in undergraduate chemistry at least. Maybe chem majors had it different. Organic chemistry 1 was basically rote memorization of various reactions and catalysts and their required conditions. Exam questions would be some organic molecule start and some organic molecule end result and you'd have to draw out each and every intermediary step to get to that end result. Organic chemistry 2 was exactly the same just more reactions to memorize. Biochem was a little easier since the exams didn't ask for full pathways but still pretty much pure memorization.

I hated these sorts off classes, where if you had your notes with you, you'd ace the exam and be able to explain everything. Passing or failing depended not on understanding, but simply whether you cram all the specifics and covered edge cases all into your head at once, given the rest of your present courseload preventing you from actually digging in to the best you could. Wrong answers didn't come from not knowing how to solve something, but not remembering exactly how to solve something.

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

#23

Post by marcosdumay »

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?

You know that people simulate chemistry on computers, right?

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

#24

Post by SlightlyLeftPad »

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?

I think this lines up with my experience. The way chemistry is often taught its very abstract, borderline magical.

I also had an amazing physics professor who was able to tie literally everything we learned back to real practical and observable events. There is an art to teaching these subjects. This is all undergrad level though, and it wasn’t my major.

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

#25

Post by zem »

asdff wrote: post #22
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?

Not in undergraduate chemistry at least. Maybe chem majors had it different. Organic chemistry 1 was basically rote memorization of various reactions and catalysts and their required conditions. Exam questions would be some organic molecule start and some organic molecule end result and you'd have to draw out each and every intermediary step to get to that end result. Organic chemistry 2 was exactly the same just mor…

I was lucky enough to have Morrison and Boyd as my undergrad ochem textbook. they built the material up really well from first principles.

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

#26

Post by timcobb »

loeg wrote: post #16
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.

Granted I took AP Chem 20 years ago, but I don't remember those names (sigma and pi bonds) being covered at all. (I got a 5 on the test, for what it's worth.)

They are not covered in AP chemistry this is just your typical "when I studied differential geometry in high school" HN comment

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

#27

Post by compass_copium »

asdff wrote: post #22
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?

Not in undergraduate chemistry at least. Maybe chem majors had it different. Organic chemistry 1 was basically rote memorization of various reactions and catalysts and their required conditions. Exam questions would be some organic molecule start and some organic molecule end result and you'd have to draw out each and every intermediary step to get to that end result. Organic chemistry 2 was exactly the same just mor…

You had a poor organic course. Even orgo 1 should have you thinking about resonance + electron-rich or -deficient areas of molecules and how those lead to reactions.

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

#28

Post by JumpCrisscross »

marcosdumay wrote: post #23
JumpCrisscross wrote: post #21

Earlier quoted context omitted.

> physics that predicts chemistry Do we have this?

You know that people simulate chemistry on computers, right?

Yes. We also simulate cosmology and quantum systems and play Sims.

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

#29

Post by compass_copium »

nerdsniper wrote: post #12
aaaronic wrote: post #11

Earlier quoted context omitted.

Yes and no. It depends which branch of chemistry you world have chosen to go down. Physical Chemistry certainly improves a fair amount of the hand waving, but even there the underlying physics is simplified fairly often (as I understand it — I went straight Physics and dabbled in Chemistry from the other side).

As a chemical engineer, one of the signs of maturity was myself and each of my classmates individually coming to accept and embrace the inevitable “magic coefficient”. The curious always wanted to know why some magic coefficient was there. Where did it come from? How is it measured / calculated? How to derive the magic coefficient? Eventually you learn that it’s turtles all the down. You can pick apart the magic coef…

Are "magic coefficients" not just a result of the units you are using? Like how h-bar is 1 if you are using natural units

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

#30

Post by scheme271 »

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?

At upper undergrad and grad levels, it probably would have improved a lot. The issue is that a lot of the why requires quantum mechanics to really explain and even that becomes intractable extremely quickly. Like you can probably do the analytic solutions for hydrogen atoms and electrons but once you get to helium or past that, you basically need to use a computer to do numeric calculations and even there, you are very quickly using approximations instead of solving the quantum equations directly.
Post reply on HN