I have a question about the rule about the first point of difference. In high school, I learned it as the "lowest sum" rule, where you add up the locants and the path giving the lowest sum was used for naming.
Then, I heard about the first point of difference, which makes sense. My question is this: I found a website talking about it, and it names the following molecule 5-ethyl-2-methylheptane.
Wouldn't the first point of difference rule name it in the reverse direction, making it 3-ethyl-6-methylheptane? Isn't "3" less than "5?"
Some help, please!