I miss almost every one of these questions on practice tests and I don't remember chad being too explicit about this, but when they ask for a possible resonance structure of a certain molecule what exactly am I looking for? Is there an order of things to look for like when ranking acids and bases? Anyone have any good resources for this? Thanks
Organic resonance structures!
- Thread starter jwan14
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In resonance structures you are only going to be looking at the bonds in a molecule. Most resonance structures come about because of the presence of one or more double or triple bonds in a molecule that allow for the drawing of more than one possible structure. The best example to follow would be the carbonate ion (CO3[2-]) in which the central carbon is double bonded to one oxygen and single bonded to the other two. There are 3 total resonance structures for this molecule in which the double bond is switched from one oxygen molecule to the next (i.e. C double bonded to O number 1, C double bonded to O number 2, and C double bonded to O number 3). So, when you are looking for possible resonance structures for a given molecule you are basically trying to see where you can move a double or triple bond in order to create another structure for that particular molecule. A couple of things to keep in mind when drawing resonance structures:
1) You do NOT want to change the position of atoms in the molecule. You are ONLY going to be rearranging bonds.
2) The charge on the molecule must stay the same. For instance in example above each resonance structure has a -2 charge.
That may be a little more information than you wanted but I hope that helps. If you still have trouble with resonance structures you probably want to review Lewis structures. Knowing how to calculate formal charge is also a helpful thing when drawing resonance structures as well just to make sure you are not over or undercharging the molecule you are drawing structures for. 👍
1) You do NOT want to change the position of atoms in the molecule. You are ONLY going to be rearranging bonds.
2) The charge on the molecule must stay the same. For instance in example above each resonance structure has a -2 charge.
That may be a little more information than you wanted but I hope that helps. If you still have trouble with resonance structures you probably want to review Lewis structures. Knowing how to calculate formal charge is also a helpful thing when drawing resonance structures as well just to make sure you are not over or undercharging the molecule you are drawing structures for. 👍
