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Yeah definitely it does. It would be great if you had a specific example so I could show you and clear it up for you. But if not, I can come up with some examples of my own.
I had one but I can't seem to find it...
That's fine, are you looking at an uncharged molecule, and what kinds of elements are you comfortable with like carbon, nitrogen, oxygen, all being in resonance? Like specifically what functional groups or types of things would you like to see in whatever example I make up, I don't wanna freak you out too bad with some weird stuff haha
I honestly can't remember. All I know is that it was an aromatic hydrocarbon. Most likely benzene, but I don't remember anything else
I will look for the paper one more time...
Ahh alright perfect example for me to play with, also sorry I was away for a few minutes. Now I'll go ahead and write out some resonance structures and then I'll explain them. |dw:1442723355192:dw| The most important rule of drawing these arrows is that you MUST start your arrow at electrons. So in this case I am starting them from a bond, and a bond is just electrons between atoms, so I'm allowed! Other than bonds, the only other place you'll find electrons are in lone pairs. Here I moved electrons from the double bond to shift the 2 electrons over to the other bond. Since electrons are negative, they canceled out the positive charge from the new place they moved to, but they left a positive charge behind. We can reverse this back and forth if we like. Perhaps this Lewis structure will help to show where the electrons moved. |dw:1442723693384:dw| Generally speaking you won't break a sigma bond, only pi-bonds which are what make up double and triple bonds. So you won't be breaking any single bonds this way, well at least not at the moment, but it is possible. I feel like I might be saying quite a bit too much so I'll try to make it a little less complicated, and end with drawing out how to get to the last resonance form and then you can ask some questions. |dw:1442723899977:dw|
One little extra thing I want to highlight is how come the charges look the way they are. Even though we're moving two electrons, at the end of the day the middle atom of these 3 has the same formal charge as before! I circled the electrons to help you see which electrons contribute to the formal charges of the atoms: |dw:1442724050737:dw|
Ok so depending on what level of organic chemistry you're at you'll either feel kind of comfortable or possibly overwhelmed. If you have a more basic or fundamental question I can help you learn that so you can fill in the gaps to grasp this, since this is pretty essential to understanding organic chemistry-- but after you understand this, the rest of organic chemistry becomes open to you, and much simpler!
so if I were to do the excersise below ( which I hope i did correctly) All I have tod do is move the electrons? But based on the one below, why do the number of double bonds change from 3 to 2 to 3?
Hell yeah awesome, since you clearly did it right on the right-most two, don't forget to write in the positive charge and double bond attaching aniline's nitrogen to the ring on the left two! Other than that, it's perfect. One other thing is it's a good idea to not just write a negative charge but also put in the electron pairs, so something like this would be good: |dw:1442728116041:dw| I guess it's not too big of a deal though, so maybe that's just my personal preference talking, depends on your teacher too I guess haha.
Also I noticed the picture is mirrored so when I say the ones on the right are correct I mean in your real life drawing the ones on the left are correct... lol
How about some more resonance practice: |dw:1443588958720:dw|