Dave Doherty
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atomsnmolecules.bsky.social
Dave Doherty
@atomsnmolecules.bsky.social
Molecular Mechanic

I make Atomsmith, which helps you to understand atoms and molecules.

USA:MSP

Edumacated on College Hill in RI:PVD.
She will gradually realize that there is no strategy to remove that Musky stink.
July 9, 2025 at 3:06 PM
Reposted by Dave Doherty
Dr. Caroline Doherty @mouthpipette.bsky.social from Dr. Laird Lab at UCSF is telling us about oocyte quality and its role in fertility during maternal aging. (An aside: Dr. Doherty is our early leader for best BlueSky handle!) Dr. Doherty discovered that support granulosa cells deliver mRNAs 7/
May 8, 2025 at 2:45 PM
wrong link?
February 17, 2025 at 3:24 PM
I'm from Connecticut, geographically between New York and Boston.

...with neither a New York or Boston accent.

GF in college was from Manhattan and went to a very ex-[clusive, pensive] private school.

She used to tell me, "My father spent a shitload of money so that I would sound like you."
January 26, 2025 at 6:34 PM
Next: "bag".
January 26, 2025 at 6:27 PM
It took me about 25 years to teach my wife (from NW WI) how to fix that. For probably about 20 of those, I don't think that she could even hear any difference.
January 26, 2025 at 6:26 PM
"A new analysis reveals that there is far more money going into AI development than there is coming out..."

I'm not prognosticating, but name a single groundbreaking technology for which that statement was not true early in its development.
January 23, 2025 at 6:35 PM
Bravo.
December 6, 2024 at 6:15 PM
Expect a full report on the airport Walgreens.
December 5, 2024 at 2:35 AM
Join the queue waiting to cozy up to Elon; he will grease the skids w TSA.
December 4, 2024 at 5:27 PM
Won't work without drive-up windows.

And TSA might have something to say about that.
December 4, 2024 at 5:23 PM
This is a case of lazy textbook authors just copying each other. LDFs are very poorly explained in intro textbooks.

To wit: the transient dipoles that create LDFs are taught as existing across whole molecules, rather than as betw atoms.

Fritz London knew this in 1936:

bitwixt.com/blog/how-ldf...
How London Dispersion Forces Really Work
Eighty-seven years later, Fritz London would like a word with us.
bitwixt.com
December 3, 2024 at 6:58 PM
Not sure why the NIST site is down.

You can search for "Pentane" and "Propane, 2,2-dimethyl-) here:

web.archive.org/web/20241110...
CCCBDB list of experimental polarizabilites
web.archive.org
December 3, 2024 at 6:50 PM
The use of n-pentane and neopentane to illustrate a (false) correlation between surface area and polarizability is all over the place.

It's considered THE classic example.

And it is WRONG.

Has no one using this example ever considered actually looking up the data?
December 3, 2024 at 6:44 PM


Higher *contact* surface area between molecules DOES lead to greater LDFs, because there are more atom-to-atom contacts/interactions.

And LDFs are an atom-to-atom interactions, not molecule-to-molecule interactions.
December 3, 2024 at 6:23 PM
source (NIST table of experimental polarizabilities):

cccbdb.nist.gov/pollistx.asp

(appears to be down at the moment)

Atomic polarizabilities are correlated with atomic volumes, which are primarily determined by their principal quantum numbers.
cccbdb.nist.gov
December 3, 2024 at 6:23 PM
"The larger the surface area the more polarizable a molecule"

The polarizability of a molecule is not correlated with surface area.

For example, examining your examples, n-pentane and neopentane (2,2-dimethylpropane):

molecular polarizability (ų)

neopentane (gas) 10.24
n-pentane (liquid) 9.88
December 3, 2024 at 6:23 PM
Then I read this at Nature about efforts at CERN to transport antimatter in a van across its campus, which mentioned this:

"Antimatter is thought to be the most expensive substance on Earth-it would cost trillions of dollars to make a gram."

Now THAT's expensive!

www.nature.com/articles/d41...
Antimatter to be transported outside a lab for first time — in a van
The volatile substance will be driven across the CERN campus in trucks to different facilities, giving scientists greater opportunities to study it.
www.nature.com
November 27, 2024 at 4:00 PM