OK, so this might be a dumb question, might be not. Im a 10th grader so bare with me please.
So I just learned what homologous series is. According to the definition that the teacher told me:
A homologous series is a series of compounds in which each member differs from the next/previous by $\ce{CH2}$ or 14 mass units. Physical properties change in a homologous series but chemical properties remain almost the same because the functional group does not change.
Now, I got a couple of question on this:
Why $\ce{CH2}$? Why not $\ce{CH4}$? What makes $\ce{CH2}$ so special that we have an entire term dedicated to a series in which every compound differs by $\ce{CH2}$?
It says that there is no change in chemical properties as the functional group does not change. Well … the hydrocarbon chain does change. So does that mean that a hydrocarbon has no unique chemical properties and all its chemical properties comes from the functional groups in it?
This is related the the 2nd question. It says that the functional group remains the same. I drew a chemical diagram thing:
Now I don't know if this is 100% correct but what I imagined is that the $\ce{CH2}$ replaced the $\ce{OH}$ and the carbon bonded with the carbon chain, then it took the $\ce{H}$ of the $\ce{OH}$ and we are left with $\ce{O}$ alone. If I am correct and if this can really happen then doesn't this mean that we are changing the chemical properties of a homologous series (which can't practically happen)?
If this example of mine is incorrect then there may be some other example like this where the $\ce{CH2}$ replaces the functional group itself thus changing the chemical properties?
This 3rd question may be illogical and stuff but I am curious.