In the following sets of resonance forms, label the major and min...

Question

In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms. d.

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e.

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Accepted Answer

Hey everyone, let's do this problem. And says for these two sets of resonance forms determine the major and minor resonance structures also identify structures of equal energy and add any missing important resonance structures. So when we're trying to decide if there could be more resonance structures, we want to see if there could be any more electron movement within the structure. So in our first resident structure in set one, we have the lone pair on this tertiary carbon moving to form a pi bond and then the neighboring pi bond moving on to that carbon atom to form a lone pair. So, can these lone pair electrons or any other lone pair electrons move anywhere else to create a new structure? Yes, this lone pair on the carbon can move down to form a carbon nitrogen double bond and that will force these pi electrons onto the oxygen. So let's draw out this electron movement so that lone pair on the carbon moves down to form that carbon nitrogen double bond electrons go onto the oxygen, which makes both oxygen atoms have a negative formal charge. The nitrogen has a positive formal charge. I had. My charge is wrong in the first structure, that positive charge on the nitrogen. And now in our second structure, the nitrogen still has a positive charge. But now our oxygen's have those two negative formal charges. So we want to see which structures have our major or minor resonance structures. So, a good way to do this is to look at which atoms are holding the formal charges. So in our first structure we have carbon nitrogen, oxygen, our second structure also carbon nitrogen, oxygen. In our third structure we have oxygen, nitrogen and oxygen. So our third structure has both of the electro negative oxygen atoms stabilizing that negative charge. And those will stabilize the negative charge better then the carbon atom as it's shown in the first two structures. So that will make our third structure the major resonance structure. So let me redraw it up here next to the other ones. And this will be our major resonance form which will make these two are minor resonance structures structures. Alright, and that is it for set one. Oops. Alright. Moving on to set two. We have the lone pair on this nitrogen here swaying down to form a double bond. And can we have any other lone pair electrons movements to form another resonance structure? Yes, we can have an identical structure where this lone pair on the other nitrogen is moving down to form that carbon nitrogen double bond which will kick these electrons back onto the other nitrogen. So let's show that movement. So this nitrogen has a lone pair. Those electrons swing down to form the double bond, kicking the electrons onto the other nitrogen, giving us the identical structure and now that positive charges on the other nitrogen. So like we said, these are identical structures. So they're going to have the same energy. And do we have major or minor resonance structures here? Well, in the first resident structure that carbon has an incomplete octet. But in these two identical structures, all the atoms have complete octet, all atoms complete octet. So these will be our major resonance structures and the first structure will be our minor structure. So we have or minor resonance structure and let me redraw our other major resonance structure and label those major resonance structures. And again, those have equal energy because they are identical structures. Those are the answers for this problem, which makes a the correct choice for this one. That's it for this problem. I hope this video is helpful and thanks for watching.

In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms. d. ⇌ e. ⇌

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In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms. d.
⇌
e.
⇌