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In rings in general, how do I determine how many unique carbons there are? In this example, I am thinking that there are 2 unique carbons (one on top and one with a double bond) since this molecule is symmetrical. Any feedback is appreciated.

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Yes, one would try to find points or lines of symmetry in general to check for equivalent ring atoms. It immensely helps to have a model and a lot of practice.

In your specific example, notice that you have two lines of symmetry in your (idealized) diagram: one passing through the sp3 carbons, and one crossing the two double bonds. You can thus "fold" the diagram into "quarters", leaving you with two non-equivalent atoms.

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  • $\begingroup$ Don't think "fold" is the right word. The symmetry would be better expressed as rotations, reflections and inversion. $\endgroup$ – MaxW Sep 10 '18 at 7:38
  • $\begingroup$ indeed that's the formal, mathematical way to put it, as reflections and other symmetry operations. I have a geometric mindset, so I always visualize things being literally sliced by planes, or being folded into equivalent halves or quarters $\endgroup$ – derek correa Sep 10 '18 at 7:50
  • $\begingroup$ so based on this, how many unique carbons would benzene have? would it be 1? $\endgroup$ – Jon Sep 10 '18 at 18:59
  • $\begingroup$ yes $\phantom{}$ $\endgroup$ – derek correa Sep 10 '18 at 19:12

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