Most people associate aromatic compounds with the word aroma. They think that all aromatic compounds smell nice instead of knowing the specific criteria that makes terms them as aromatic. To understand these characteristics properly, I will define them in terms that everyone can understand not just people with a background in chemistry.
First, the compound must be cyclic. But what does that mean? To understand this, think of a ring. A ring is a circle and for a compound to be aromatic it must be shaped like this. This is the easiest way to comprehend the first rule.
Second, the molecule must be planar. Think of a piece of cardboard with rubber balls attached to each side. All of the balls on the top side should be equivalent. For example, the balls should all be the same color, shape, and size. The same goes for the underside. The piece of cardboard represents the molecule and the balls represent the orbital. All of these aspects are on the same plane, which makes the molecule planar.
Third, the molecule should be completely conjugated. What does it mean to be completely conjugate? To understand this, think of a group of girls who are holding hands to form a circle. This represents the molecule and each girl represents an atom. Aromatic molecules must have a p orbital on every atom. So think of every girl as having the same hat on, this could represent the p orbital.
Fourth, the molecule must satisfy Huckel’s rule and contain a particular number of pi electrons. An aromatic compound must contain 4n + 2 pi electrons. This rule is the hardest to understand. Pi refers to the p orbital as explained above. The electrons in pi bonds are referred to as pi electrons. To understand this, relate the pi electrons that are needed to make a compound aromatic with the p orbital analogy in rule three.
You did a pretty good job on explaining aromaticity. You covered each criteria thoroughly, but I felt like a few things were missing. When talking about the molecule being cyclic, you did not explain that aromaticity can also occur if you have numerous rings fused together. Also I found your analogies for rules #2 and #3 a bit confusing. Being planar just means that the compounds is flat. Talking about balls being different might confuse the layperson because you did not explain what the color has to do with anything. For the third rule, you did not include anything about resonance. I don't think you need to include what resonance is, but mentioning that the electrons of pi bonds do not stay in one place would be good. Thats all I have =)
ReplyDelete-The High School Chemist
I'm sorry you found some of my analogies confusing. I tried to think of simple ones but it was really hard to explain chemistry to a person who has no knowledge of the subject. For rule #2 I meant for the cardboard to represent the molecule being flat but the balls are supposed to represent the orbitals. Like each ball must be the same in every aspect(color, shape, size, etc.) just like the p orbitals. I hope that helps you understand it a little better. I chose not to include resonance in my explaination because to the layperson that might be too confusing. Especially since it's not a rule for aromaticity itself. If I was explaining it to a fellow chemistry student I probably would have included that detail. Thank you for your feedback!
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