Hey Grandma,
I know how badly you want to learn about aromaticity, so I thought I would help you out and give you the high points. There are four main criteria that determine if a compound is aromatic or not.
The first of these is that the compound must be cyclic. This means exactly what it sounds like; the compound must continue in a ring or cycle.
The second criteria is the compound must be planar (flat). If there are more than six carbons forming the cycle of the compound, then it must take on a shape other than a ring to remain planar. An aromatic compound can also remain planar by fusing rings, which means that two or more rings will be attached to each other.
The third requirement is the molecule must be completely conjugated; meaning every carbon in the compound must have a double bond on it. This can become complicated when looking at 3D models because the double bonds do not stay between the same two carbons, but for 2D models, each carbon will have a double bond on it.
The final requirement is the molecule must follow what is called Huckel’s rule. This rule states that to be aromatic, a compound must have 4n+2 pi electrons, the electrons that make up the second bond of a double bond. To figure this, count the number of double bonds and multiply by 2. If the result follows the 4n+2, then you are good to go. Anyways good luck with your search for new knowledge.
Your Favorite Grandson,
Don Kelly (The High School Chemist)
Good job on explaining a difficult topic concisely. The only spots that might be difficult for a non-science student to understand would be the last point, 4n+2 pi electrons. Although you did explain that pi electrons were "the electrons that make up the second bond of a double bond," it might be helpful to add a picture of what that looks like. I know that for myself pictures always help explaining difficult topics. As the say "as picture says a thousand words."
ReplyDeleteAlso to be specific I'm not sure conjugated rings have a double bond on every carbon but instead have 1.5 bond angle length, since they are all sharing 3 double bonds.
I'm sure your grandma is proud of her "favorite grandson."