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Maks

What is wrong with the Kekulé structures for benzene?

Benzene molecule C6H6 is known as the most famous aromatic cyclic hydrocarbons.
Its molecular formula, C6H6 , was established in 1834, after the compound's discovery by Faraday.
The formula of benzene (C6H6) caused a mystery for many years after its discovery, as no explanation had been found that could account for all the bonds — carbon usually forms
four single bonds and hydrogen one.
The chemist Fredric Auguet Kekulé was the first to deduce the ring structure of benzene (1865).
The cyclic nature of benzene was confirmed by the crystallographer Kathleen Lonsdale.
Using X-ray diffraction, researchers discovered that all of the carbon-carbon bonds in benzene are of the same length, and it is known that a single bond is longer than a double
bond. In addition, the bond length, the distance between the two bonded atoms in benzene is greater than a double bond, but shorter than a single bond. There seemed to be in
effect, a bond and a half between each carbon.
The first people who proposed the benzene structure were chemist Archibald Scott Couper and chemist Josef Loschmidt but without scientific evidence.
There were several other structures proposed for benzene, but no sufficient model of the structure was provided until many years later.
Currently, chemists know very well about this molecule but since it was found for the first time, benzene was known has un-usual structure.
The current explanation for benzene's structure is that the bonds between the carbon atoms of benzene are all the same, with bond angles 120 degrees between them. Benzene
is also a planar molecule (all the atoms lie in one plane). Each carbon atom is bonded to its neighbor with one electron from each atom. Since each atom has two neighbors, this
uses two electrons from each atom. Another electron from each carbon is used to bond the hydrogen attached to it. The remaining six electrons orbit the atomic nuclei at right
angles to the plane of the ring and also overlap each other, consequently blurring their orbits both above and below the ring ( 3 electrons in upper ring and 3 electrons in down
ring). As a result, the electrons are shared equally between the carbon atoms and exist as two clouds, one above and one below the plane of the carbon ring. Since these latter
six electrons are not confined to specific carbon atoms, they are said to be delocalised. This is usually represented in structural formula as a hexagon with a circle in the centre
to represent the shared nature of the electrons.

Is it so?
Is this a correct structure of benzene?
So I ask scientific community?
Is anybody now the correct geometrical structure of benzene with all atoms ( 6 Carbon’s and 6 Hydrogen’s) and all electrons round them which
will satisfy all we know about Benzene molecule?

Maks,
Sapo
I can't imagine that anything is 'wrong' with it.

See this thread. http://forum.physorg.com/index.php?showtopic=18569&hl=

I hope that leads you to a better understanding.
Maks
Sapo,
I saw the link.
But, Do you really think that such sp hibrid orbitals and such attraction between pi electrons exist?
Please tell me where I can find Theory for attraction between electrons. They repulse each other do not attract. Please do not involve spin orientation.
And also, in every book of Chemistry you can find that visualitation of sp hibrid orbitals is almost impossible without clouds or circles.
Maybe sp orbitals are involved in theory only to cover our ignorance.
So, I ask again. Is it possible to show 3d geometrical picture of Benzene molecule (with all his attributes) and with all atoms and electrons (not in clouds or circles) round them.
Maks
El_Machinae
e- ARE best shown by probability clouds though
soundhertz
http://www.nanowerk.com/spotlight/spotid=2693.php

You might like this article about theoretically changing molecules into transistors. Benzene is the preferred hydrocarbon. Additional links.
rpenner
What is obviously the wrong way to think about intramolecular bonding is in terms of balls (atoms) and sticks (bonds). It just so happens that this approximation is useful in some circumstances. For benzene, the physical fact that all the C-C and C-H bonds are the same as the other C-C and C-H bonds remains best explained by quantum field theory of the electron, which means that hybridization (superposition) is inescapable when it comes to describing the system.

In benzene, the C-C bond is not a "single" or "double" bond, but part of an "aromatic ring" and is 0.1399 nm in length (the C-H bond is 0.1101 nm in length).

In contrast, the C-C single bond in cyclohexane (C6H12) is 0.1536 nm in length, which is similar to the C-C bond in ethane (C2H6) of 0.15351 nm, while the C-H bond stays in the 0.1094-0.1101 range.
C-C double bonds are typically closer to 0.130 nm.
C-C triple bonds are typically closer to 0.118 nm.

The above is based on the 1985 version of the Cambridge Structural Database (CSD) for average bond lengths in crystalline organic compounds and Kagaku Benran (Chemistry Handbook), 3rd Edition (1985) for specific bond lengths of named gaseous compounds as determined by electron diffraction and/or infrared spectroscopy. These values were also gathered and reprinted in such sources as newer volumes of the CRC Handbook of Chemistry and Physics.

// Edit:
Or maybe I'm over-thinking this because I actually did some advanced chemistry in college including quantum mechanics. Maybe this is just homework help. Maybe I didn't need to actually translate Japanese to English.

The Kekulé structure (alternating single and double bonds) would break the hexagonal symmetry of benzene -- making it impossible to have a planar shape of a regular hexagon and modern infrared studies of benzene indicate there is only one type of C~C bond. Not two types as in the in Kekulé (proposed) structure (C-C, C=C). Also, a lot of double bonds would lead to predictions that benzene is a compound which is more reactive than experience indicates.

http://www.chemguide.co.uk/basicorg/bonding/benzene1.html
Trippy
So here's the deal (I imagine that people have been wondering whether or not I've been going to find this thread)...

Actually, I'm not sure where to start. One of the things that becomes apparent to me reading the OP, and some of the responses to it is that first off, the paring of electrons hasn't been understood properly.

Basically, when electrons pair, they do so through spin-spin coupling. Basically, what it boils down to is that although electrons experience electrostatic repulsion, when their spins are opposed, they experience some attractive forces. It is these attractive forces that allow two electrons to overcome the electrostatic repulsion between them. I suppose the easiest way to understand this is to bare in mind that at all times, electrons behave like tiny little bar magnets (as can some nucleii) so when their spins are opposed, the 'bar magnets' are pointing in opposite directions, so the magnetic moments of the electrons exert a partially attractive force. The electron has a magnetic moment because it is a spinning electric charge.

So I hope that clears that up.
Electrons have spin.
Electrons have charge.
Because electrons have spin and charge, they have a magnetic moment.
Said magnetic moment enables a particaly attractive force to develop between to electrons with opposing spins.

Now onto Benzene.

Benzene has two resonance structures.
User posted image

Now. We all know that double bonds are shorter then single bonds. But which bonds are the single bonds, and which bonds are the single bonds are again?

You can't, because it's not that clear cut.

So, the easiest way of describing what happens next, is that if you consider the 'classical' interpretation of resonance structures, we find ourselves considering that bezene is continually 'switching' between the two configurations. Of course, this should give rise to vibration modes in the structure that simply aren't observed, and quantum mechanics us that the correct answer is that it exists in both states simultaneously.

What this tells us, essentially is that the bond angles should be consistent with sp2 hybridized carbon, but that the lengths should be intermediate between sp3 and sp2, an observation which we can also confirm experimentaly (as detailed in the original post).

What fronteir molecular orbital theory tells us, is that interpreting benzene as existing in an 'average' state is in fact completely accurate.

These are the Pi molecular orbitals for benzene:

User posted image

There are two significant features in the diagram.

The first of these is that the lowest energy molecular orbital is the simplest (hence being the lowest energy) it is what happens when we give all 6 Pi orbitals on the same side of the ring plane the same sign. The end result of this configuration is that both electrons are delocalized over the entire structure of the ring.

The next two orbitals are degenerate (that is have the same energy) and are formed by having pi orbitals with opposing signs on the same side of the ring plane - this effectively introduces a second node plane (the first being the ring plane). There are only two possible configurations for this (hence the two degenerate energy levels) the second nodal plane in both cases is orthogonal to teh first, the difference is that in one, the second nodal plane bisects a side, in the other it bisects an angle.

One of the points that you should note is that all six electrons fit in Benzene's bonding orbitals, this is (part of) what makes benzene so stable (and so toxic - it's toxic because the same stability still applies to radicals of bezene - this is why we use toluene as a solvent in place of benzene - for reasons I wont go into right now, the introduction of the methyl group to the ring destabilizes the ability of the ring to produce radicals).

the other thing that you should notice, that's pertinent to the discussion, is that all 6 pi electrons are, in essence, delocalized over all 6 carbon atoms. Based on this we are lead inexorably to the conclusion that each carbon atom shares 1.5 bonds with each of it's neighbouring carbon atoms, because there are only enough Pi electrons available to form 3 Pi bonds, but those 3 Pi bonds, as demonstrated by the resonance approach, and the fronteir molecular orbital approach, are smeared equally around 6 atoms, so each carbon shares half a Pi bond with each of it's neighbours.

I hope that helps clarify things. If not, feel free to ask further questions, I'll do my best to answer them.
Maks
Hi,
The Question Has Not Been Answered Yet. Again clouds and circles.

QUOTE from site about Benzene molecule:
Every now and then, someone announces that the "theory of chemistry" is complete, is wrong. One can only wonder what chemistry textbooks will look like 50 years from now. Alan Shusterman, - ROCO - REED ORGANIC CHEMISTRY ONLINE.


Spin-spin coupling das not make conection.
And in every Theory about covalent bonding (Molecular Bond Theory, Molecular orbital theory, Quantum field theory of the electron, …), at the end is conclusion, beside all is said before, that there are no other forces than electrostatic.
To involve in Theory attractive forces that allow two electrons to overcome the electrostatic repulsion between them, is without any foundation.
Maybe some formulas will help.
And how, only with 3 electrons up or 3 electrons down in Benzene molecule, can be made ring (circle)?

Maks,

Sapo
Maks, IMHO, rpenner and Trippy both gave succinct and cogent responses to your question, in the process enlightening even me. laugh.gif

What do you misunderstand? Try again...
Maks
My question is:
Is it possible to show 3d geometrical picture of Benzene molecule (with all his attributes) and with all atoms and electrons (not in clouds or circles) round them.

What do you misunderstand? Try again...
Trippy
QUOTE (Maks+Oct 19 2007, 09:26 AM)
Hi,
The Question Has Not Been Answered Yet. Again clouds and circles.

QUOTE from site about Benzene molecule:
Every now and then, someone announces that the "theory of chemistry" is complete, is wrong. One can only wonder what chemistry textbooks will look like 50 years from now. Alan Shusterman, - ROCO - REED ORGANIC CHEMISTRY ONLINE.


Spin-spin coupling das not make conection.
And in every Theory about covalent bonding (Molecular Bond Theory, Molecular orbital theory, Quantum field theory of the electron, …), at the end is conclusion, beside all is said before, that there are no other forces than electrostatic.
To involve in Theory attractive forces that allow two electrons to overcome the electrostatic repulsion between them, is without any foundation.
Maybe some formulas will help.
And how, only with 3 electrons up or 3 electrons down in Benzene molecule, can be made ring (circle)?

Maks,

You ever heard of a 2 electron 3 center bond?

It happens because of the way the s and p orbitals add together.

Atomic orbitals add, overlap, and change their shape.

Let me put it to you another way.

Take the simplest pi orbital.

You have 6 lobes sticking above the plain of the ring, and 6 below it.

Why would a p orbital only bond with the ones on either side of it, when there are three other orbitals that it could equally share some sort of a bond with.

If spin-spin coupling is a myth, then what holds together the covalent bonds that make up your body? Why do you not simply fly apart? Or for that matter, why do the first couple of rows of the periodic table have full shells at 2,8 rather then 1,4?

And again, we come back to the fact that an electron has a magnetic moment as well as an electrostatic charge (in fact it has a magnetic moment because it has angular momentum and an electrostatic charge).

Then there's the hyperfine splitting of Hydrogen, and the forbidden transition in Iron that gives glass it's green colour (when viewing a bulk sample) both of these are examples of spin-flip transitions.

The hyperfine splitting of hydrogen occurs because of - I think it can be coupling between the spin of the nucleus, and spin of the electron, with the transition being from a paralell state to an antiparalell state, which gives us an emission at 21cm.

The forbidden transition in Iron occurs because, IIRC, Fe(II) looses its 4s electrons before it looses it's 5d electrons (Fe(III) also represents a 'stable' electron configuration because it has a half full d-shell). This means that Fe(II) has 6 5d elecetrons to be distributed between 5 electrons.

In studying complexes we find that the 5 d orbitals are split in the presence of ligands into two groups, one which has a high energy, and one which has a low energy (e_g and t_2g). This is crucial because this is part of the observational evidence that we have that spin coupling occurs between electrons. What we find is that the same oxidation state can exist in two different electronic configurations, depending on the strength of the electroc field that it is in. In one configuration that electrons occupy the higher energy level orbitals, because doing so takes less energy then pairing the electrons together does. In the other configuration, we find that the electrons prefer to be paired together, because the energy taken to do this is less then the energy required to occupy the higher energy orbitals.

Back to the forbidden Fe(II) transition in glass.

Basically, what we find is that the Fe(II) in glass is in the confguration with upaired electrons (low field configuration) basically, what happens, is a transition is moving from a low energy state, to a high energy state. But, because the higher energy orbitals all have unpaired electrons in them, the electron must flip its spin to make this transition. Normally this transition is what is termed a "forbidden transition" but there are a bunch of factors which can allow it to happen occasionally (thus we now define things as being strongly forbidden or weakly forbidden).

Thus, in summary.
We have observational evidence that the Electron has spin.
We have observational evidence that the electron has charge.
We have observational evidence that the electron has a magnetic moment.
We have observational evidence that electrons pair up on the basis of opposing spins, although this requires some energy to do.
We also happen to have observational evidence that fronteir molecular orbital theory is at least on the right track - in otherwords if something better comes along to replace it then it must give the same correct results that FMO gives, and will probably look like FMO under (most) circumstances where FMO is correct.
I'm also aware that there are some things that (AFAIK) FMO has been the only thing to explain (IIRC, the action of mustard gas was one of them, and the diels-alder reaction was another, not to mention the bonding of oxygen in hemoglobin, the structure of benzene, and a slew of results in organo metallic, and transition metal chemistry).

I hope this helps clarify things?
Sapo
I'll just bet it doesn't. sad.gif

Where is his picture? blink.gif
Maks
Sapo, Trippy

There are two answers for my question: Yes or no

If ist yes, show me.

If is it no, I will show you.

Maks,
Trippy
QUOTE (Maks+Oct 19 2007, 10:00 AM)
My question is:
Is it possible to show 3d geometrical picture of Benzene molecule (with all his attributes) and with all atoms and electrons (not in clouds or circles) round them.

What do you misunderstand? Try again...

There's no simple yes or no answer to this question.

That's why Benzene is represented like this:

User posted image

The bond is drawn as a dashed line because each carbon behaves as if it has 1.5 bonds to the carbons on either side of it.

Or with a circle in the middle of it (as shown on the left)

User posted image

The reason why the circle is used is to illustrate the observed fact that Benzene behaves as if those 6 electrons are shared between all 6 carbon atoms in this manner:

user posted imageuser posted image *edit: Note, curly arrows indicate the movement of electron pairs.

As has been said, Bezene doesn't exist as one structure or the other, it exists as the average of the two structures.

You're going to come across this a lot, and you can thank quantum mechanics, and the wave-like properties of an electron for that.

The electrons don't exist in specific locations, they behave as if they occupy the entire orbital, and atoms, and electrons interact with each other as if the electrons occupied the whole orbital.

That really is the simplest way I can think of to explain it without going into quantum physics in depth.
Maks
Sapo,Trippy...

Here is 3d Benzene molecule image!

The tekst below is part of my site:
Universal Periodic table

s and p hybridization problem

As we can see from the table , Electron configuration 2 (according spectral data), and with the minimum energy principle and also with new postulates, another big problem or mystery in the Chemistry is solved. That is s and p orbital hybridization (6.Carbon and 16.Silicon). So for the Carbon atom, instead orbital filling 1s2 , 2s2 ,2p2 , new filling order is 1s2 , 2s2 ,3s2 (all four last electrons are s electrons, two per different orbital's). Same case is with 14.Silicon. Instead filling order 1s2 , 2s2 , 2p6, 3s2, 3p2, the filling order is 1s2, 2s2, 2p6, 3s2, 4s2. So there is no need for s and p hybridization of the orbital's, or clouds to cover the reality.

For example the molecule Benzene C6H6:

Benzene (C6H6) is one of the most fascinating molecule. The structure of benzene was for many years a problem for chemists, as problem of real nature of bonds in molecules. The real structure of this molecule is enigma until present days.

( QUOTE from site about Benzene:Every now and then, someone announces that the "theory of chemistry" is complete, is wrong. One can only wonder what chemistry textbooks will look like 50 years from now. Alan Shusterman, - ROCO - REED ORGANIC CHEMISTRY ONLINE ).

Benzene is a perfectly regular hexagon. Benzene is also a planar molecule (all the atoms lie in one plane), All bonds angles = 120 degrees. All the bonds are exactly the same.

So, in the geometrical structure in well know aromatic molecule Benzene C6H6, there is no need for s and p hybridization. All four Carbon electrons are s electrons. All angles in C atom are tetrahedral. In the molecule there are 30 electrons ( 24 Carbon and 6 Hydrogen ). There are 12 between Carbon and Hydrogen, 6 between Carbon atoms ( sigma electrons) and 6 in upper and 6 in down ring ( pi electrons).( Flying Saucer shape).

Connections between Carbon atoms are not with two (single connection with single bond's length C-C 0.154nm) or four electrons ( double connection with double bond's lenght C=C 0.134 nm) but with three electrons, ( one and a half connection). The lengths of all the bonds are 0.140 nm with new mark C- =C (one-half bond). The lenghts of C - H bonds are 0.110 nm.
User posted image
Notice: this image is no so good. All connection are same.

[Same type of bond (one-half bond) can be found in two isostructural forms of Butadiene molecule also ( H2C= =CH- -CH= = CH2 ) ( H2C= -CH= =CH- =CH2, or H2C= -CH= -CH= =CH2 ).

(There are also connections with five electrons, two-half bond. All molecules with so call resonances - CO2, O3 and so on).

The new geometrical structure ( with included position of the s electrons), is perfect example of extraordinary balance of the positive and negative fields or forces in the molecule C6H6. All atoms in molecule balance round their position without any chance to move anywhere.
This structure is shown in the images below, which are for the first time, in this site, shown on the internet. All dimension between atoms and electrons are in compatibility with their real dimensions in molecule.
User posted image
User posted image
User posted image
With this new geometrical structure of the Benzene molecule it's very easy to explain Electrophylic aromatic substitution. For example: attached electron in upper ring (one from six), together with Electrophyle (coming somewhere from the center of the ring), with rotation, took place of Hydrogen's atom at the outside Carbon electron. The rotation is made round electron between C atoms ( sigma electron) so the aromatic ring is not destroyed. Do not forget, all angles are tetrahedral. The electron in down ring go to position in upper ring. The outside electron go to position in down ring. Hydrogen's proton in this dynamic events lose the connection with his own electron, which electron stay in connection with Carbon atom, and go away. Hydrogen's proton is replaced with Electrophyle.

With this new geometrical structure it's also easy to join another Benzene molecule by replacing two Hydrogen atoms and form Napthalene C10H8, Anthracene C14H10, Phenathrene C14H10 and much moore bigger molecules. Bond between Benzene molecules are with single, one-half or double bond connection, depending of Carbon atoms orientation. This has direct implication for the type of the ring in Benzene molecules (aromatic or not aromatic), for angles and also for bond's length.

Et the end it must be sed that, in the nature of all bond connection between atoms in molecules, there is no mystery. They are only electrostatic in dynamic environment.

Maks,

Trippy
QUOTE (Maks+Oct 20 2007, 09:23 AM)
Sapo,Trippy...

Here is 3d Benzene molecule image!

The tekst below is part of my site:
Universal Periodic table

s and p hybridization problem

As we can see from the table , Electron configuration 2 (according spectral data), and with the minimum energy principle and also with new postulates, another big problem or mystery in the Chemistry is solved. That is s and p orbital hybridization (6.Carbon and 16.Silicon). So for the Carbon atom, instead orbital filling 1s2 , 2s2 ,2p2 , new filling order is 1s2 , 2s2 ,3s2 (all four last electrons are s electrons, two per different orbital's). Same case is with 14.Silicon. Instead filling order 1s2 , 2s2 , 2p6, 3s2, 3p2, the filling order is 1s2, 2s2, 2p6, 3s2, 4s2. So there is no need for s and p hybridization of the orbital's, or clouds to cover the reality.

For example the molecule Benzene C6H6:

Benzene (C6H6) is one of the most fascinating molecule. The structure of benzene was for many years a problem for chemists, as problem of real nature of bonds in molecules. The real structure of this molecule is enigma until present days.

( QUOTE from site about Benzene:Every now and then, someone announces that the "theory of chemistry" is complete, is wrong. One can only wonder what chemistry textbooks will look like 50 years from now. Alan Shusterman, - ROCO - REED ORGANIC CHEMISTRY ONLINE ).

Benzene is a perfectly regular hexagon. Benzene is also a planar molecule (all the atoms lie in one plane), All bonds angles = 120 degrees. All the bonds are exactly the same.

So, in the geometrical structure in well know aromatic molecule Benzene C6H6, there is no need for s and p hybridization. All four Carbon electrons are s electrons. All angles in C atom are tetrahedral. In the molecule there are 30 electrons ( 24 Carbon and 6 Hydrogen ). There are 12 between Carbon and Hydrogen, 6 between Carbon atoms ( sigma electrons) and 6 in upper and 6 in down ring ( pi electrons).( Flying Saucer shape).

Connections between Carbon atoms are not with two (single connection with single bond's length C-C 0.154nm) or four electrons ( double connection with double bond's lenght C=C 0.134 nm) but with three electrons, ( one and a half connection). The lengths of all the bonds are 0.140 nm with new mark C- =C (one-half bond). The lenghts of C - H bonds are 0.110 nm.
User posted image
Notice: this image is no so good. All connection are same.

[Same type of bond (one-half bond) can be found in two isostructural forms of Butadiene molecule also ( H2C= =CH- -CH= = CH2 ) ( H2C= -CH= =CH- =CH2, or H2C= -CH= -CH= =CH2 ).

(There are also connections with five electrons, two-half bond. All molecules with so call resonances - CO2, O3 and so on).

The new geometrical structure ( with included position of the s electrons), is perfect example of extraordinary balance of the positive and negative fields or forces in the molecule C6H6. All atoms in molecule balance round their position without any chance to move anywhere.
This structure is shown in the images below, which are for the first time, in this site, shown on the internet. All dimension between atoms and electrons are in compatibility with their real dimensions in molecule.
User posted image
User posted image
User posted image
With this new geometrical structure of the Benzene molecule it's very easy to explain Electrophylic aromatic substitution. For example: attached electron in upper ring (one from six), together with Electrophyle (coming somewhere from the center of the ring), with rotation, took place of Hydrogen's atom at the outside Carbon electron. The rotation is made round electron between C atoms ( sigma electron) so the aromatic ring is not destroyed. Do not forget, all angles are tetrahedral. The electron in down ring go to position in upper ring. The outside electron go to position in down ring. Hydrogen's proton in this dynamic events lose the connection with his own electron, which electron stay in connection with Carbon atom, and go away. Hydrogen's proton is replaced with Electrophyle.

With this new geometrical structure it's also easy to join another Benzene molecule by replacing two Hydrogen atoms and form Napthalene C10H8, Anthracene C14H10, Phenathrene C14H10 and much moore bigger molecules. Bond between Benzene molecules are with single, one-half or double bond connection, depending of Carbon atoms orientation. This has direct implication for the type of the ring in Benzene molecules (aromatic or not aromatic), for angles and also for bond's length.

Et the end it must be sed that, in the nature of all bond connection between atoms in molecules, there is no mystery. They are only electrostatic in dynamic environment.

Maks,

I'm on holiday at the m,oment, and staying with my inlaws, and given the way this thread has developed, I'm finding myself increasingly disinclined to go into any detail, but, there are a multitude of things wrong, or that aren't taken into account.

The most obvious thing that springs into my mind is that your model completely fails to take into account the observed symetry of Pi bonds.
Maks
There is no images in my preview post! I don't now why!

You have only site address.

Trippy, do not worry about Pi bond symmetry. Everything is OK

There is also unusual 3d image for C2H4 also.

Maks,
Trippy
QUOTE (Maks+Oct 23 2007, 07:50 AM)
There is no images in my preview post! I don't now why!

You have only site address.

Trippy, do not worry about Pi bond symmetry. Everything is OK

There is also unusual 3d image for C2H4 also.

Maks,

No, everything is not okay. Your theory adds to things with sigma symmetry together and some how magically produces something with Pi symmetry, and you have not explained how this works. Let alone how your theory accounts for the unusual stability of some TM ions.
Maks
First,
there is new 3d images of Napthalene - C10H8 somewhere at the middle of the site

Universal Periodic Table

Second: what is new with this images and Theory?

The new is: the electrons. When they lose their energy with atoms impact, they
became slow motion electrons and with their big negative electromagnetic field (same as proton) they act like extra light elements. So they also balance about their positions same as six Hydrogen protons. They differ from electrons in atom orbitals. The question is do we really need s and p orbitals.

Maks,



Trippy
QUOTE (Maks+Oct 24 2007, 10:20 AM)
First,
there is new 3d images of Napthalene - C10H8 somewhere at the middle of the site

Universal Periodic Table

Second: what is new with this images and Theory?

The new is: the electrons. When they lose their energy with atoms impact, they
became slow motion electrons and with their big negative electromagnetic field (same as proton) they act like extra light elements. So they also balance about their positions same as six Hydrogen protons. They differ from electrons in atom orbitals. The question is do we really need s and p orbitals.

Maks,

The answer is yes, we do, and there's too many observations that your conjecture doesn't account for, for example. THE SYMMETRY OF PI BONDS.
Maks
Hi, Trippy

If our intention is better understanding of molecule bonding nature, we must agree that any geometric structural model of molecule bonding or molecule orbital is not complete without positions of the electrons.

Historically, the hybridisation theory was promoted by chemist Linus Pauling in order to explain the structure of molecules such as methane (CH4). This concept was developed for such simple chemical systems but the approach was later applied more widely.

But what if hi was wrong. What if all our knolling about hybridization, delocalizations, resonance’s structures and so on, is not complete. This dilemma is n't new?

Professor William F. Coleman from Dept. of Chemistry, Wellesley College in his Chemistry internet site “ Rethinking Hybridization” sed:
For more than 60 years, one of the most used concepts to come out of the valence bond model developed by L. Pauling was that of hybrid orbitals. The ideas of hybridization seemed to be consistent with many experimental observations. Hybrid orbitals were simple to envision, they predicted geometries most of the time for simple p-block compounds and they made the distinction between sigma and pi bonding easy to understand. However, it has always been true that when molecular structures and properties are probed more deeply, the hybrid orbital model – particularly the extreme limits of the model presented in introductory and organic chemistry texts – presents many difficulties.

So what are we to do? One option is to abandon the hybrid orbital model completely and to make descriptions based solely on the molecular orbital coefficients. Another, and perhaps one that is more palatable to many chemists, is to rethink what we mean by hybridization, and realize that all it really means is that orbitals of the same symmetry have been involved in forming a molecular wavefunction.

Also Feng Wang, from Centre for Molecular Simulation, Swinburne University of Technology, Internal Mail Box H39, Hawthorn, Melbourne, Vic. 3122, Australia in his site Abstract: Molecular orbitals of methane: symmetry or hybridization? hase conclusion: There are no any quantitative evidences of hybridization for the MOs of methane in either coordinate space or momentum space.

About Benzene's Symmetry: (somewhere from internet)

One i, Center of inversion
One C6 rotation axis perpendicular to the molecular plane
One C3 rotation axis perpendicular to the molecular plane.
One C2 rotation axis perpendicular to the molecular plane.
Three C2' rotation axes in the molecular plane.
Three C2" rotation axes in the molecular plane.
One sh reflection plane corresponding to the molecular plane.
Three sv reflection planes containing the principal axis (C6).
Three sd reflection planes containing the principal axis (C6)
One S6 improper axis coincident with the C6 axis.
One S3 improper axis coincident with the C3 axis.


Also, Carbon atoms in Benzene molecule have local tetrahedral symmetry. Carbon atoms, in molecules, always have tetrahedral orientations of his four electrons. So the electrons in benzene molecule are same (except spin) and there is no pi electrons. They are only with his own different energy stages or levels. They act, as I said before, like extra light elements.
The analysis of positive and negative fields in Bezene molecule show that, moving of any electrons from his position in molecule is almost impossible without external energy disturbance (with another electrons, ions, radicals, atoms or molecules, or maybe physical propetries of environment).
So there is no need for pi symmetry.
The Hydrogen and electrons round Carbon atom in Benzene molecule (one from six), can rotate about all four tetrahedral axes. That is the key for transporting atoms or electrons thru or between molecules, not clouds of the electrons. That is the key for so many differences between so many molecules in Organic and Inorganic Chemistry, and key for polymerization and bigger molecules or crystals.
So this Theory, Hypothesis or model, cover old facts and gave something new, which is not in big collision with that old facts. With three electron bonding and the new notation, with one and two dashes ( 1,5) bond order, and with new approach for bonding between atoms in molecules, can be solved another “weird” molecules or some molecules that can't quite completely satify all of the requirements that Lewis thought all molecules wanted to have.

Maks,

Trippy
Your theory also fails to properly account for bond angles.

Accorind to your theory the angle between two hydrogen atoms on the same carbon should be 109.5 (or was it 107.5) but we in fact measure it to be 120
Maks
Nothing false with my Theory!
All angles fit very well.
Benzene is a perfectly regular hexagon. Benzene is also a planar molecule (all the atoms lie in one plane), All bonds angles = 120 degrees. All the bonds are exactly the same. All angles in Carbon atoms are 109,5 degrees Tetrahedral).
As I said before, with this new geometrical structure it's also easy to join another Benzene molecule by replacing two Hydrogen atoms and form Napthalene C10H8
And again all angles and distances fit very well.
Here is image for Napthalene

User posted image
User posted image
User posted image

and for Ethylene

User posted image
User posted image
User posted image

Ethylene molecule C2 H4 is example for double bonding of Carbon atoms and planar positions of the Hydrogen molecules. Angle between Hydrogen atoms is 117 degrees. All angles in Carbon atoms are 109,5 degrees (Tetrahedral). Bond length between Carbon atoms is 134 pm.
Covalent bonding between carbon atoms are same as between H2 molecule, but with four electrons.

Maks,
Trippy
You're missing the point.

We observe the angles in Benzene, Napthalene, and Ethylene to be 120 degrees, not 117 or 109.5
Maks
Hi Trippy,

You are missing the point.

All angles between Carbon and Hydrogen atoms in Benzene and Napthalene are 120 degrees.
That is obvious from the images.

For Ethylene experimental angle between Hydrogen atoms at first was 118, than 117 degrees.

But electrons in Carbon atoms always have 109, 5 degrees, not Hydrogen.

Even in cyclopropan C3H6 they have 109,5 degrees, not 60 degrees.

In B, N or O, electrons have different angles between them round central atom.

Maks,
Maks
Once again Benzene molecule with angles!

User posted image

If there is no image go to link Universal Periodic Table

Maks,
Trippy
QUOTE (Maks+Nov 10 2007, 07:12 AM)
Hi Trippy,

You are missing the point.

All angles between Carbon and Hydrogen atoms in Benzene and Napthalene are 120 degrees.
That is obvious from the images.

For Ethylene experimental angle between Hydrogen atoms at first was 118, than 117 degrees.

But electrons in Carbon atoms always have 109, 5 degrees, not Hydrogen.

Even in cyclopropan C3H6 they have 109,5 degrees, not 60 degrees.

In B, N or O, electrons have different angles between them round central atom.

Maks,

I think you're the one missing the point.

Electrons in Carbon atoms only have 109.5 degrees if they're sp3 hybridized.

The difference in bond angles between B, N, and O, even when compared to C is purely accountable for by the fact that non-bonding electrons (aka lone pairs) sit closer to the atom then bonding electrons - this is just common sense, when you bare in mind that bonding orbitals are between two atoms.

There's no mysteries in anything you're talking about.
Maks
Hi,
Besides that the Benzene problem discussion sink deep in Puzzling question pages , the interest for this discussion is still very high.
So to purport my 1,5 bonding type in Benzene molecule I made pictures of aromatic and non aromatic compounds.
Here are some examples of DNA bases.
User posted image: User posted image
User posted image: User posted image
User posted image: User posted image
User posted image: User posted image

This pictures and many others are part of my site Universal Periodic System.
In this site You can find also the new quantum shell number ns with new shell and subshell scheme. The big difference with old scheme is that now there is no more s,p,d,f ..... order (2,8,18,32),.or (2, 2 6, 2 6 10, 2 6 10 14,...), but ss,pp,dd,ff ... order (2-2,8-8,18-18, 32-32), (2,2, 6 2, 6 2, 10 6 2, 10 6 2, 14 10 6 2, 14 10 6 2,...), same as the new shape table. This has the big implication in spectroscopic analysis.You can also find new Diborane bond connection, new Metallocene sandwich compound pictures, new aromaticity rules and many other interesting things.

Maks,
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