Great post, enjoyed it!
A technical mistake here: “Fat is made of fatty acids—chains of carbon atoms linked via hydrogen bonds”. They are linked via covalent bonds, not hydrogen bonds.
For those who don’t know: covalent bond is a strong chemical bond that forms when two atoms provide one electron each to form an electron pair. These are normal bonds that hold molecules together. They are shown as sticks when one draws a molecule. Hydrogen bond is a much weaker intermolecular bond that forms when one molecule has an atom with an unshared electron pair and the other has a hydrogen atom that sort-of has an orbital to fit this electron pair.
And also having a chain of carbon atoms is about “fatty” part, and the “acid” part means that at the end of this chain there is a carboxyl group. I know that’s not the point of this post, it just hurts a little, I’m sorry.
Well, EB article you linked doesn’t state directly that fatty acids are made out of carbon atoms linked via hydrogen bonds. It has two sentences relevant to the topic, and I am not entirely sure how to parse them:
The first sentence is (almost)[1] correct.
The second sentence, if viewed without the first one, may technically also be correct, but for what I know it’s not and also it’s not what they meant. See, fatty acids are capable of forming actual hydrogen bonds with each other with their “acid” parts (attached the picture from my organic chem course). On the left covalent bonds are shown with solid lines and hydrogen bonds are shown with dashed lines. The “fatty” part of the molecule is hidden under the letter R. On the right there is methyl instead of R (ie it’s vinegar) and hydrogen bonds are not shown—molecules are just oriented in the right way. (I’m really sorry if I’m overexplaining, I just want to make it understandable for people with different backgrounds).
So, if interpreted literally, the second sentence states that unsaturated fatty acids form less hydrogen bonds with each other for whatever reason, and that’s why they are liquid instead of solid. The explanation I’ve heard many times is different, it says that they are liquid because their “fatty” part is bent because double bonds have different geometry, so it is harder for them to form a crystal. I mean, it is still possible that they also form less hydrogen bonds, but I bet it’s insignificant even if true.
But it honestly looks like they don’t mean all of that at all, they are just incorrectly calling covalent bonds between carbon and hydrogen “hydrogen bonds” and they also don’t know what they mean by “the structures are weaker”. It’s still a sin, but not the one you are accusing them of.
I am also completely fine with the phrasing that is currently in the article and I’m sorry for wasting your time with all that overthinking, hope it wasn’t totally useless.
The “fatty” part of a fatty acid molecule can’t be called a “hydrocarbon molecule” since it is, well, a part of another molecule, and should rather be called “hydrocarbyl group” (see eg Wikipedia). Also the article should say “at least two carbons” instead of “two carbons” because, as this post is well aware, there exist polyunsaturated fatty acids.