 Here's a compound that I've made out of the little Mollymod kits. This particular one has one, two, three, four carbons and then a number of hydrogens around those. As a little aside, it's important that when you are drawing, and I'll draw this for you in just a moment in terms of its structural formula, you need to make sure that every carbon has four bonds. Now, occasionally they may bond with more than one bond between two atoms, but either way, they always need to have, all our carbons need to have four bonds. So it's a good quick way of double checking that you've drawn a molecule correctly. So this one has four. So if we were to draw this particular molecule, then it would look like this. So what I do is make sure that I've got enough bonds to ensure that there are four bonds around every carbon. And once I've put all of the important things that I need to put in, then I just fill everything else up with hydrogens. So in this case, it's all hydrogens around the carbons. So we have a four carbon and three, five, seven, ten hydrogens. So the molecular formula for this compound would be C4H10. But what's its name? Well, its name is the name that we give to a compound that has four carbons. So therefore, that would be its prefix. And its suffix would be the fact that there's only single bonds. So therefore, that's going to be an aim. So the name of this compound would be butane. When we're talking about methyl groups, what we're talking about is an additional hydrocarbon that sits on the side. Now, if I was to add this to this particular molecule, if I put it in the position on the end, then all I'm going to do is to increase the length of the chain. So now I have one, two, three, four, five. I have five carbons in this chain. And so therefore, since it's still only single bonds, it would now be called pent.