 So in organic chemistry we often talk about functional groups and functional groups are groups of atoms that can be added to hydrocarbon chain for example. And so I've listed some of the major functional groups that students in biology might be interested in. One group is a hydroxyl group and this is what alcohols are all about. So if you see OH attached to an organic compound that you know that's a functional group and alcohol. Another group is a double bonded oxygen attached to the carbon and this is called a carbonyl group. If the double bonded oxygen is at the end of a chain then that particular substance is called an aldehyde. If that double bonded oxygen is in the middle of the chain or it is not on the end then that's a substance called a ketone. Then we can have carboxylic acid groups. Vinegar for example has a carboxylic acid group attached to it and that's a carbon with both a double bonded oxygen and a hydroxyl group attached to it. Then there's a group called a mean group and that's a nitrogen with two hydrogens attached to it. And then we have a phosphate group and the phosphate group is an oxygen with a phosphate or phosphorus and three oxygens attached and you see that carries a charge of negative 2. Alright so let's look at some alcohols for example. This if you'll count has two carbons attached to it and so our prefix for two is F and you see we have a single bond between the carbons and so that means that it would be an A-N for the alkanes that have all single bonds and then you see our OH group which makes it an alcohol. So this is F-N-O-L-E-T-H-A-N-O-L. So it's a carbon with a hydroxyl group attached and then that carbons attached to another carbon that has four or three hydrogens. Let's look at propanol and so probe tells us that we have three carbons one two three so there are our three carbons and then here is our OH group or our hydroxyl group. So this is propanol probe for three carbons propanol. But let's look at an isomer of propanol and that will be isopropanol and with isopropanol you can see that the middle carbon is the one that has the hydroxyl group attached to it. So here's carbon carbon carbon and then the hydroxyl group attached to the middle. So propanol and isopropanol are isomers of one another. They both have the same molecular formula that you can see that their structural formula is very difficult.