All right guys, so hopefully you got that the longest chain was actually this one right here. I know that can be tricky to visualize because you're not used to thinking of curving around stuff. You're used to seeing things just from left to right and things in a straight line. But the longest chain just is the longest continuous chain of atoms. So that would be that swirly one right there. Okay? So how many is that? That looks like 1, 2, 3, 4, 5, 6, 7, 8, 9. So this is going to be that the root equals nonane. Cool with that so far?
Now we have to determine the direction. So this one's actually pretty easy. This is my one in blue. This is my one in red. Which one is going to be the direction? Which one is going to be a better direction? And obviously it would be the blue. Okay? Because the blue, I'm going to get to my first substituent at the 3 position, whereas with the red, I wouldn't get to my first substituent until the 5 position. Okay. So that one's just that one's just a loser. Red sucks. Okay.
So now I have my numbering determined. Now I have to identify and locate all the substituents. The easiest way to do this is just to number the entire chain. So I'm just going to say 2, 3, 4, 5, 6, 7, 8, 9. How many substitutions do I have? I have 2. I have 1 on the 3 and 1 on the 5. Okay? So the way we're actually going to name these, I'm just going to put here subs. Okay. Now I'm getting hungry. The way we're going to put these is by naming the location with a hyphen and then we're going to say what the actual alkyl group is. I'm going to teach you more about this as we move down the page, but I'm just telling you this for right now. So one of the substituents would be 3-methyl. By the way, if you didn't add the hyphen, that's totally fine because I haven't taught you that yet. Okay? But just so you know, if you just put 3 methyl, that's fine. But it's actually 3-methyl, that would be one substituent. Another substituent would be 5-ethyl. Does that make sense? Because I have an ethyl group on the 5 and a methyl group on the 3. Awesome.