50 votes
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Do molecules with bridges through rings exist?

I'm not sure about the existence of molecules with bridges through rings. However, there are several publications of synthesis of molecules mimicking wheels and axles ([2]rotaxanes; The “[2]” refers ...
Mathew Mahindaratne's user avatar
49 votes
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What is the molecular structure of xenon hexafluoride?

TL;DR Xenon hexafluoride has a fluxional structure in the gas phase, with multiple rapidly interconverting conformers. The three most important conformers have $C_\mathrm{3v}$, $O_\mathrm{h}$, and $C_\...
orthocresol's user avatar
43 votes
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Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?

Yes. Researchers have been using atomic force microscopy (AFM) and scanning tunneling microscopy (STM) for some time for this purpose. Do note that these images are not photographs in the sense that ...
Todd Minehardt's user avatar
30 votes

Do molecules with bridges through rings exist?

A variation on this theme is Ice VII, in which two cubic ice structures are intertwined with hydrogen bonds from each component structure passing through the hydrogen-bonded rings formed by the other ...
Oscar Lanzi's user avatar
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27 votes
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Why do the atoms in molecular models have the colors they have?

There's an interesting article here - Illustrating Atoms and Molecules - that discusses atom colors: In 1865, the chemist August Hoffman gave a Friday Evening Discourse at London’s Royal ...
gilleain's user avatar
  • 1,735
27 votes
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How can you build a model of tetrahedral coordination from objects found at home?

Inflate balloons, and tie them «at their stem» like a bouquet of flowers. If you take four of them, not too much inflated, you well demonstrate a situation close to $sp^3$ hybridization. These models ...
Buttonwood's user avatar
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26 votes
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Why does the image of cyclo[18]carbon look like a nonagon?

The first thing to say is that I'm not sure where that image is taken from; it's neither in the original article nor in the supporting information to the article. Therefore, it appears to be more of ...
orthocresol's user avatar
25 votes

Does benzene structure stand for a single resonance form or the whole molecule?

The answer is you are referring to neither of them. That is because resonance structures don't actually exist in reality. We only use them to give us a rough idea what the actually molecule and bonds ...
Nanoputian's user avatar
  • 7,372
24 votes

Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?

In addition to the answer provided by Todd, there is also the very established technique of single crystal X-ray diffraction. The basic principle is sending X-rays through a single crystal of a ...
Jan's user avatar
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23 votes
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What are the important implications to the field of chemistry, if any, of the hexavalent carbon species confirmed in 2017?

The carbon is not hexavalent, it is hexacoordinated. A covalent bond does not equal to a total of two electrons between the bonding partners and the nature of the chemical bond may lie somewhere ...
Martin - マーチン's user avatar
23 votes
Accepted

Why is cyclooctateraene shaped like a "tub" rather than a "chair"?

It's all about the 3D structure of double bonds. If we look at the tub form we see that all dihedral C-C=C-C angles are 0°. the C=C-C angles are 125°, also pretty close to the optimal value. ...
DSVA's user avatar
  • 5,772
22 votes
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Structure of Br3O8

The electron didn't go anywhere. It's in an unhybridized p orbital on the central bromine, and yes, $\ce{Br3O8}$ is a free radical. That is why it decomposes above -80ºC.$^{[1]}$ $^{[1]}$ Cotton, F. ...
ringo's user avatar
  • 24k
22 votes

Aside from carbon, what other substances can be made "superhard"?

Interestingly, nobody addressed the reason why diamonds are hard in the first place. The pressure (and temperature) are not the reason why they're hard, only the reason why they are formed. The ...
David LUC's user avatar
  • 339
21 votes

Why does bond angle decrease in the order H2O, H2S, H2Se?

The question asks why water has a larger angle than other hydrides of the form $\ce{XH2}$ in particular $\ce{H2S}$ and $\ce{H2Se}$. There have been other similar questions, so an attempt at a general ...
porphyrin's user avatar
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21 votes

Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?

In 2005, a field ion microscope captured an image of a very sharp tungsten needle. The small round features are individual atoms. At even smaller scale than molecules, a quantum microscope has ...
Dan Dascalescu's user avatar
21 votes

Aside from carbon, what other substances can be made "superhard"?

Here are some compounds that have other structures, followed by their hardest structure (based on Moh's Scale). Titanium dioxide: Rutile structure or Cotunnite structure Aluminum oxide: Corundum ...
CoffeeIsLife's user avatar
  • 4,284
21 votes

What is this fluorinated organic substance?

The name of the compound is 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (CAS #: 140681-55-6), which is commonly known as Selectfluor, a trademark of Air Products ...
Mathew Mahindaratne's user avatar
20 votes
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Why do we not generally have "enneane"?

Perhaps not a complete answer, but this might put you on the right track. It looks as though a lot of the system we have today grew out of recommendations made by August Wilhelm von Hofmann in a paper ...
Tyberius's user avatar
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19 votes
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Why are the two CH2 groups in allene perpendicular to each other?

No, VSEPR theory does not allow for a coplanar arrangement. Let us consider allene and its orbitals: Source. Green indicates $\mathrm{p}$ orbitals; blue $\mathrm{sp^2}$; and red $\mathrm{s}$. ...
ringo's user avatar
  • 24k
19 votes
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Can Fe(CO)5 adopt both square pyramidal and trigonal bipyramidal geometries?

Your book was correct that a five coordinate metal complex is able to adopt both square pyramidal and trigonal bipyramidal geometries, and in both cases the sp3d hybridisation scheme applies (if you ...
NotEvans.'s user avatar
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19 votes

Is a compound composed out of gold, manganese, xenon, krypton, and oxalate possible?

No, this is not possible. Actually, if I would have to think of the most unlikely chemical conceivable, that would be it. Let's see why: Krypton is a noble gas that doesn't bond to anything. All of ...
Gimelist's user avatar
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18 votes
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Complex organic molecules

tl;dr: two different definitions. Astronomy: multiple carbon atoms in molecule. Chemistry: polymer Interestingly enough, after reading about COMs here, as well as reading the Wikipedia page and the ...
JSCoder says Reinstate Monica's user avatar
17 votes
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Help understanding how "steric effects" are distinct from "electronic effects"?

The normal distinction between "steric" and "electronic" is based on whether the effect is transmitted through space or through bonds All the normal physical interactions we ...
matt_black's user avatar
16 votes
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Why does the fructose monomer in sucrose appear different from isolated fructose?

Ah, a (fairly) common conundrum that assails us Chemistry students when we start Biochem. ;-) At first glance, the fructose molecule in your first picture, and that in the second picture appear to ...
paracetamol's user avatar
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16 votes
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What would the chemical name be for C13H8Cl3NO

Well, let's reconstruct that starting from the very right side, where it says a $\ce{C_6H_5}$. The ring and the $\ce{CO}$ group would be a benzaldehyde if it had an $\ce{H}$ instead of an $\ce{N}$, ...
Justanotherchemist's user avatar
16 votes
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What is quasi-aromaticity?

In general, we can describe a quasi aromatic compound as a compound, which is ionic in nature with a counter ion, and the $\pi$ electrons in such compounds follow Huckel's rule ($4n+2$). In other ...
Mathew Mahindaratne's user avatar
16 votes
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Caffeine molecule representation and orientation

Wondering if there are IUPAC rules or conventions about structure orientation. There are recommendations, which aren't really rules per se (in fact even the IUPAC nomenclature books are all ...
orthocresol's user avatar
15 votes
Accepted

How can AuCl3 exist?

Gold(III) chloride does not exist as $\ce{AuCl3}$. According to Wikipedia, the name gold trichloride is a simplification of the name, which is referring to the empirical formula, $\ce{AuCl3}$. The X-...
Mathew Mahindaratne's user avatar
15 votes

How can I determine the size of tropolone molecule?

You wanted to measure the distance "across tropolone" but you didn't specify from where to where. The distance from a remote hydrogen to each of the oxygens and to the hydroxyl hydrogen are ...
user55119's user avatar
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