So what are constitutional ice MERS their compounds that have the same exact molecular formulas, meaning that both the compounds will have all the same atoms in them. But what is different about them is their connectivity. So go ahead and write that down connectivity. What does that mean? Connectivity has to do with the way the atoms are bonded to each other. So, for example, of my first molecule has Adams a linked to be linked to see or bonded to A B and C, My second molecule might have the same Adams A, B and C, but they're arranged differently. So maybe is connected to C and then see is connected to B. That would be an example of a constitutionalism. For this course, what you're gonna have to be able to do is you're gonna have to be able to look at two different compounds and tell, What is that relationship? Are they the same compound, meaning that everything is exactly the same in terms of the molecular formula and the connectivity? Or are they completely different compounds, meaning that they have different atoms all entirely? And then there's this other category, which is are they constitutional ice summers, which means that they have the same atoms, but they're connected differently and it can be really tricky. Thio differentiate which one is which? That's why I have made this nice little flow chart for you guys to follow. All right, so

so imagine that you're given this question right here. This is the This is an exam. How are the following Two compounds related. Are they identical constitutional ice, summers or different compounds? Where do you even begin? Well, it turns out that this question is, I think a little bit beyond your level. All of you guys are probably a little bit stumped by this question. You might think that you know the right answer, and you might be right, but most likely you didn't get to the answer in a systematic way. So I want to teach you guys is the systematic way to get these problems right every single time. All right, so we're gonna come up back up to that question. But what I actually want to do is go through these steps right here on these steps, will guide you through constitutionalism or questions, okay, And notice that it uses I h d. That's why I had to teach you the HD first because that's the easiest way to tell the difference between different types of compounds. So my first question that I have to have to ask myself makes sense. It's just are all the atoms the same. Okay, because remember I told you that in order to be a constitutionalism, all the atoms have to be exactly the same. So the way that we tell a lot of students, what they do is they start counting every single atom, all in in the entire molecule, and they compared to the other one. And then obviously they see if they're the same or not. But what I What I would recommend is don't count the hydrogen. Okay, Count on Lee non hydrogen atoms and then count the HD in both compounds. The reason why is because I HD is actually just a measurement of hydrogen. Remember that ihe would tell you how many hydrogen zehr missing. So and I HD happens to be much easier to calculate the number of hydrogen. You know why? Because if you have to calculate number of hydrogen, that means you're looking at a bond line structure. You're gonna have to first put all the hydrogen in there and then you might have so many hydrogen is that you might miss count. And that happens all the time with students. So what I prefer is hey, instead of counting each h out at a time. Just use the HD instead. The HD is a placeholder for a number of hydrogen. So now check this out. If those two numbers are not exactly the same. So if I have a different amount of non hydrogen atoms or a different amount of I h d in both of the atoms in the both of the molecules, then these were going to be different compounds. Why are they different compounds? Well, because if they don't have the same atoms, then they're just automatically different. Okay. Ah, compound can only be the same as another compound if it has the same exact Adams inside of it. Okay, So that would be the answer for this question. Appear if we found that they had different amounts of carbons, which is a non hydrogen atom or different amounts of HD, But let's keep going and see what happens if they happen. Toe lineup. Meaning that the non hydrogen atoms and the HDR exactly the same in both. Then we go to step two. Okay, what is Step two will step to make sense as well. Now I'm gonna ask myself. Are all the atoms connected? Exactly the same way. Okay, Now it turns out that most of the time this is gonna be a very easy question to answer. Most of the time, you're going to see your two compounds, and they're gonna look very different. For example, one of them is a square, and one of them is a four carbon chain. Would that be the same thing? Would it be the same thing if I had a square on one side for carbon chain on the other side? Would you say that they're connected the same way? Absolutely not. They will completely different. The only way that they could be connected. The same is if every atom is connected to the same Adam on the other molecule. Alright, so most of the time, common sense is just gonna tell me yes or no. Either they look the same or they don't. But sometimes you get a situation like up here where these two molecules above me, they look like they're kind of similar, but maybe they're rotated. I don't know. Okay, so for this one, we're gonna want to use a systematic method, okay? And what I always say is, toe look for what I call a landmark Adam. Okay, now, this is not a word that you're gonna find in your book, so don't look for landmark. Adam isn't anything. It's just a word that I used to say. Look for something that stands out. Okay. So you would look for something that stands out that you can compare to everything that you can compare in both molecules. Okay, So, for example, maybe if your compound has an oxygen in it, then you would look at where the oxygen is in the first one and where the oxygen is in the second one and see, Are they in the same place? If your oxygen has I mean, if your compound has something else like a ring in it, maybe you look at the ring and you say, Is the ring in the same place in both? Okay, if they're not exactly the same thing, that means that you have constitutionalism. Er's why? Because that means that we got to step two, which means all the atoms in the HD was the same. But then step to. What we said is that they are not exactly the same in the way they're connected. So that's constitutional items. That's the definition of a constitutional I summers of other constitutionalism. Er okay, what if they are the same, though? So let's say that means that now all my atoms are the same and they're connected exactly the same. Then those were just going to be identical compounds. Does that make sense? And those are my three options.