ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: WhoTookMyUsername on April 23, 2011, 12:04:36 pm
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I'm a tad confused about the properties of Benzene.
Does anyone know chemicals / molecules with similar chemical propities to Benzene?
And also why is ethane etc. not similar in reactions, but similar in structure?
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Ethane isn't similar in structure to Benzene at all.
Benzene is cyclic in nature, ethane is a two carbon chain (I'm not sure what it is specifically called).
Another cyclic compound you may see in VCE is Cyclohexane; C6H12, except the carbons are bonded in a circular nature.
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This is ridiculous, you are only like 2 chapters behind me and are in year 11.
But yeah, they are completely different structurally. Similarities they have are... both are hydrocarbons and share the general properties of them?
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okay thanks, i'll have a look at aromatic hydrocarbons.
This is necessary for a project we're doing, we have to present about a molecule, and i chose Benzene not knowing its complexity :(
Yeah we figured. How would you show the double bonds? Benzene double bonds move. Your project just jumped from Styrofoam and toothpicks to needing a motor!
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Yeah we figured. How would you show the double bonds? Benzene double bonds move.
There are no double bonds... Look up resonance for more info.
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lol. I think i'll just do double bonds and single bonds and talk about the limitations of the model and cop a B
Dude, everyone cops at least an A...
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lol. I think i'll just do double bonds and single bonds and talk about the limitations of the model and cop a B
Dude, everyone cops at least an A...
Disappointed in you Bazza, B's not good enough.
Moderator action: removed real name, sorry for the inconvenience
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Yeah we figured. How would you show the double bonds? Benzene double bonds move.
There are no double bonds... Look up resonance for more info.
Aren't there alternating double bonds?
Moderator action: removed real name, sorry for the inconvenience
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Right yeah, delocalised electrons. I still think I've read in quite a few places that there are double bonds.
*waits for Mao*
EDIT: seriously if anyone knows what I am confusing, please let me know... CONFUS.
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Right yeah, delocalised electrons. I still think I've read in quite a few places that there are double bonds.
*waits for Mao*
EDIT: seriously if anyone knows what I am confusing, please let me know... CONFUS.
it's a ring of delocalised electrons, where the bonds are basically all equal in length with them being somewhere between a single and double bond.. so the benzene ring shares the double bonds.
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I thought it was alternating double bonds as well. :\
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
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Oh right, thanks man. Was confusing me.
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Oh right, thanks man. Was confusing me.
This website is fantastic for all things chem: http://www.chemguide.co.uk/
Here is their page on benzene, with lots of extra detail. Only if you're interested in learning a bit more... http://www.chemguide.co.uk/basicorg/bonding/benzene1.html
Yes - resonance is electron sharing where you find the 'real' structure / observed structure is a combination of two 'drawn' structures.
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
I don't agree with this. Electrons aren't confined to 'bonds'. Classical models only allow single and double bonds. The only way to explain the structure of benzene using classical models is that the bonds are alternating.
In more advanced theory (ones that treat electrons with quantum mechanics), you have delocalisation.
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wut, wut, wut, I always thought Benzene had alternating double bonds... =S
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
I don't agree with this. Electrons aren't confined to 'bonds'. Classical models only allow single and double bonds. The only way to explain the structure of benzene using classical models is that the bonds are alternating.
In more advanced theory (ones that treat electrons with quantum mechanics), you have delocalisation.
Yes, Mao is correct. Neither of the resonance structures of Benzene is strictly correct.
Rather, the electrons which are supposed to be involved in the double bonds are delocalised around the whole ring, which is what gives this molecule its stability.
This is why some people prefer the benzene structure with the ring drawn on the inside of the hexagon, however it has limitations, the biggest being it makes it difficult to keep track of electrons.
This is Uni level stuff, so don't worry about it too much.
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
I don't agree with this. Electrons aren't confined to 'bonds'. Classical models only allow single and double bonds. The only way to explain the structure of benzene using classical models is that the bonds are alternating.
In more advanced theory (ones that treat electrons with quantum mechanics), you have delocalisation.
Yah but the resonance structure shows all bonds are of equal length and strength, somewhere intermediate between a double and single bond, hence a partial double bond.
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This idea about resonance structures - think about benzene as an "average" of each of the resonance structures. When you "average" the resonance structures out, you find that the electrons are delocalised around the whole ring.
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
I don't agree with this. Electrons aren't confined to 'bonds'. Classical models only allow single and double bonds. The only way to explain the structure of benzene using classical models is that the bonds are alternating.
In more advanced theory (ones that treat electrons with quantum mechanics), you have delocalisation.
Yah but the resonance structure shows all bonds are of equal length and strength, somewhere intermediate between a double and single bond, hence a partial double bond.
Just watch this:
http://www.youtube.com/watch?v=-EFEfVDUp6M
Edit:
Don't worry about all the stuff about sp2 orbitials, p orbitals, sigma bonds and pi bonds. just take note that each carbon has 4 electrons. two which bond with the adjacent carbons electrons to form covelent bonds, another electron which binds with hydrogen to form a covelent bond, and a remaining electron which remains delocalised and contributes to the ring.
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This is resonance as someone mentioned above. It is where the theoretical molecule isn't the same as what we observe. To explain this discrepancy we say that the electron pairs are able to jump around between adjacent atoms to form partial double bonds.
I don't agree with this. Electrons aren't confined to 'bonds'. Classical models only allow single and double bonds. The only way to explain the structure of benzene using classical models is that the bonds are alternating.
In more advanced theory (ones that treat electrons with quantum mechanics), you have delocalisation.
Yah but the resonance structure shows all bonds are of equal length and strength, somewhere intermediate between a double and single bond, hence a partial double bond.
I think you are misunderstanding the term 'resonance structure'. A molecule can have several resonance structures, each of them contributing to the overall structure (i.e. the actual structure). Individual resonance structures follow the classical model. The method of 'averaging' these resonance structures is the attempt to explain the '1.5 bond' phenomenon.
Resonance structures are useful in organic chemistry, though most chemists don't agree with its premise.