 In naming ionic compounds you need to get comfortable with two things. You need to be able to write the name of the compound by looking at its formula and you need to be able to write the formula of the compound from its name. Let's do writing the name from the formula first, it's relatively easy. All you need to be able to do is recognize the ions in the formula and know their names. So let's run through some examples. Our first one here, you can see that it's made from sodium and fluorine. We know that the positive metal ion comes first and that it has the same name as the original element. The negative non-metal ion comes next and we replace the end of the name with id. So instead of fluorine, we have fluoride. So the name of this compound, NAF, is sodium fluoride. Next one we have here is made from the elements lithium and sulfur. The sulfur is the negative ion, that's going to become sulfide. So the name of the compound will be lithium sulfide. This one here, FE is iron, it's one of those elements that doesn't have an obvious symbol. So it's made from iron and oxygen. The iron keeps its name, the oxygen is the anion so it becomes oxide and the name of that compound is iron oxide. This next one, SR is strontium, burns with a beautiful red colour strontium and it's also made from iodine. The iodine is the negative element, the negative ion, so it will become iodide. The full name of the ionic compound is strontium iodide. Okay, those four were all ionic compounds that used monatomic ions. In the case of three of them, you can see that some of the ions occur more than once. So in lithium sulfide, for instance, you've got two lithium ions to every one sulfide ion. And in iron oxide, you've got two iron ions to every three oxygen ions. We will get into how you work that out in just a little while. These next ones, however, they're made from metal cations but polyatomic anions. And really all you need to be able to do here is recognise the polyatomic anions. So in this first case, we've got magnesium is the metal ion, so it retains its name. And you should be able to recognise now that SO4 is the sulfate anion. So we just write sulfate. So the name of this compound is magnesium sulfate. This next one here, PB is lead. And the OH here is the hydroxide anion. The fact that it's been put in brackets with the little two means that you have two hydroxides. So two separate hydroxide anions for every one lead cation. This one here is a little bit tricky. You need to look quite closely. But again, if you're familiar with your polyatomic ions, you'll notice that the cation here is ammonium. It's one of the few cations that's not metal based. And the anion here is nitrate. So that's ammonium nitrate. One of the most common fertilisers and explosives bases in the world. This last one here, we've got two aluminium ions. And the polyatomic ion is the anion is carbonate, CO3. And you can see it's in brackets with a little three. That means there are three carbonate anions for every two aluminiums.