 Let's start our discussion now on functional groups of organic molecules. So the first series, I guess, of functional groups that I'd like to go over are the hydrocarbons. And these are just like what they sound like. We talked about these earlier a little bit. These are just like what they sound like. They're only compounds that are hydrogen and carbon, composed of hydrogen and carbon. So remember, we could have the saturated hydrocarbons. Those were all C, H, or C, C single bonds, right? So if you remember, the formula was C and A. Do you guys remember H2N plus 2? OK, so that's the formula for a saturated hydrocarbon. And an example of something like that would be, well, like methane or butane or peclotexane. Think of a lot of things. Now, you can draw a bunch of them, billions of them. These ones, though, do not follow this formula because they have a ring. So you can only have the straight chain or the, sorry, not just the straight chain, but the non-ring stuff. So this is not a straight chain, but it still has this one. So there's other type of hydrocarbons, not just saturated ones. So saturated have only C, H, and C, C bonds, like that. But we have unsaturated ones. All the saturated ones are called alkanes. This is alkane, alkane, alkane, alkane. Unsaturated means I have at least one double bond or one triple bond, double bond or one triple bond. It can mean I have 1,000 double bonds or triple bonds. Or it means I can have two double bonds, a triple bond, a single bond. OK, I can have all of that stuff and be unsaturated. So unsaturated hydrocarbons, remember, only carbon and hydrogen. So I have to have at least one double bond in there. Those are all unsaturated. They all have at least one double bond. Anything with one double bond in it is called an alkene. So notice the E instead of the A. So all of those compounds I just drew, they're all alkene. And then a molecule can have a triple bond and be unsaturated like so. If you've got a triple bond in you, you're now called an alkyne. In fact, it's the functional group. Functional group is essentially any sort of structure that's within an organic molecule. So the functional groups for alkenes are CH single bonds. The functional group for alkenes are CC double bonds. Some functional group for alkynes are CC triple bonds. And that's going to make one bond, one bond. This is why I drew it like this. Why did I drew it like that? Draw it like that, because it's 180 degrees. So remember your bond angle. What's the bond angle here? You guys remember? 1, 1, 1. What's the bond angle here? 1, 9.5. Why? Because there's four things bonded to that. So it's tetrahedral. Have a watch out about this. So what's the bond angle here and here? What about here? Yeah, 120. Why? Because this carbon has a double bond to it. So this carbon here, trigonal pyramidal. This carbon here is tetrahedral. So it's trigonal pyramidal. So it's tetrahedral. So it's tetrahedral. Just like that. Unsaturated alkenes, alkynes. Saturated hydrocarbons, alkanes. Any questions? Again, this applies to only these type of alkanes, OK? Not to ring alkanes. And we'll talk about alkanes.