 In this video, we're going to look at the situation where you have more than one functional group in a molecule. For instance, if you had a molecule that contained both an alcohol group and a ketone group, how would you name that? Well, here's our list of functional groups again. And it's in the same order that we've been using so far, but you'll notice that I've added a few new columns. On the left I've put numbers in order from 1 to 10, and that indicates the priority of the group or how important it is. So when we have two functional groups in a molecule, the way we solve the naming problem is to make one of them the suffix of the name and to treat the other one like a substituent. But how to choose which one? Well, IUPAC have come up with this list of priorities for that very purpose. When you have two functional groups in a molecule, whichever one is higher up on this list will be the one that determines the suffix of the name. It will be treated exactly like all the examples we've done in previous videos. The other, lower priority functional group will be named like a substituent. And for that purpose, each group has another name that's used in this situation. For instance, when a molecule just has an aldehyde group in it, the name ends with the suffix L. But say it has both an aldehyde and a carboxylic acid. Then the name will end in the suffix OEC acid because the carboxylic acid is higher priority. And somewhere at the front of the name, we will have a substituent called OXO. And that indicates the lower priority aldehyde group. Note down all these prefix versions of the functional group names. And then let's move on and try out some examples.