 Before I begin talking to you about functional groups, I want to show you some notation. Imagine I want to tell you about the following molecule. But the part I'm specifically interested in is the OH group here, the oxygen and hydrogen, and not really the rest of the molecule. Then I can draw it R-OH. The R means some organic bit, but it's not important what it is. The bit attached to the R is what we're really interested in. This R notation will turn up a fair bit when we want to emphasise some part of a molecule without needing to specify what the rest of the molecule is. So this video is about functional groups. A functional group is a group of atoms other than singly bonded carbons and hydrogens that's attached to a basic hydrocarbon molecule, and which has some particular effect on its chemical and physical properties. In the molecule I drew above, the functional group is the OH. The backbone, if you like, of the molecule is butane, but we have this extra OH group attached, and it's called a functional group. There are many kinds of functional groups, and this particular one is called an alcohol. Let's have a look at some more. The table I have here has a list of functional groups. This is not exhaustive, but it contains all the groups we need to know for now. The family column on the left tells you the name given to all molecules that have this functional group. And I'm going to draw in the group of atoms that makes up each functional group. I'm going to start at the bottom of the table and work up. The reason for this particular ordering will become clear in a later video. Several of the simpler families are already familiar to you. The alkanes, the alkenes, and the alkynes. Alkanes don't really have a functional group since they're the most basic of hydrocarbons. Alkenes have a double bond, and alkynes have a triple bond. Propene is an example of an alkene. The next family is the alkylhalides, or the haloalkanes. These molecules are identical to alkanes, except that one or more of the hydrogens in the molecule is replaced by a halogen atom. This could be fluorine, chlorine, bromine, or iodine. The halogen atom constitutes the functional group. An example of one of these is this, and it's known as bromopropane. Next we have the amines. Here, a nitrogen and two hydrogens are added to the molecule. An example would be propanamine. These molecules have behaviour in common with ammonia, from which they are derived. Ammonia is a base, a proton acceptor, and so are amines. Next is the alcohols. These molecules all have in common the OH functional group that you saw on the previous slide, an oxygen and a hydrogen. An example of one of these would be propanol. Next the ketones. These have a double bonded oxygen attached to one of the middle carbons of the molecule. So an example of this is propanone, also commonly known as acetone. Note that the C double bond O group by itself is called a carbonyl group. Then we have the aldehydes. These molecules also have a carbonyl group, the C double bond O, but it will always be at the end of the molecule, not in the middle. Here's an example, this one's known as propanol. Next are the amines. Here you take a carbonyl group and you join an amine to it, and together that makes an amide. This molecule is propanamide. Then the esters. Again you take a carbonyl group and then add an oxygen and another hydrocarbon part. This ester is called methylpropanoate. And finally carboxylic acids. In this functional group there is a carbonyl group on the end of the carbon chain and an alcohol group is attached to it. The name carboxylic acid is not a coincidence because of the proximity of the two electronegative oxygen atoms, which draw electron density away, it's easy for this end hydrogen here to drop off and become a lone proton, a hydrogen ion. Hence when these compounds dissolve in water, they dissociate to give hydrogen ions. An example of one of these is propanoic acid.