Question

I am not sure if I answered the question below correctly and if I need all the information in my answer. Do I need all of this information?

Why does the simplest ketone have 3 carbon atoms and no less?
The simplest ketone has three carbon atoms and no less because of the carbon-oxygen double bond and it has a dipole as well. The oxygen atoms and two single pairs of electrons are much more electronegative than the carbon atom. With this it means it has a strong dipole with a partial negative charge on the oxygen and a partial positive charge on the carbon. The polarity of the ketone has a strong influence of its chemical and physical properties. A ketone also is bonded to two alkyl groups (also known as aromatic rings).

Answer 1

I just know that in order to be a ketone, this functional group looks like this C-C(O)-C so it must have at least 3 carbons to be a ketone... I don't know if you have to explain using eletronegativity or dipole...

Answer 2

Personally, I think you have given a lot of detail, which, although correct, is not needed for it doesn't address the question. For example, I don't think the fact that the simplest ketone has three C atoms has anything to do with the polarity of the molecule, although I think what you wrote is correct. Also, although the carbonyl group has a great influence on the chemical and physical properties, again, I don't think that has anything to do with the fact that the simplest ketone has three C atoms. Think along the lines of the definition of a ketone. A ketone has a C=O group with TWO groups attached to the C atom. NEITHER of those two groups can be a hydrogen atom (then you would have an aldehyde). Ergo, three C atoms is the simplest. I'm not an organic chemist; I'm sure you can write that in much more esoteric terms than I have written.