So what are constitutional isomers? They're compounds that have the same exact molecular formulas, meaning that both of 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, if my first molecule has atoms linked to or bonded to, my second molecule might have the same atoms, but they're arranged differently. So maybe one atom is connected to another and then to another; that would be an example of a constitutional isomer.
For this course, what you're going to have to be able to do is you're going to have to be able to look at two different compounds and tell what that relationship is. 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 entirely? And then there's this other category, which is are they constitutional isomers, which means that they have the same atoms, but they're connected differently. It can be really tricky to differentiate which one is which. And that's why I've made this nice little flowchart for you guys to follow. All right?