[Music] Hey guys, this is Mr. Millings and in this video we are going to learn how to name and memorize polyatomic ions. So if you take a look at this table right here, what we're looking at is a table of 27 common polyatomic ions that you might see in a firstear college level chemistry course or a high school chemistry course for that matter. So if you take a look at some of these common polyatomic ions, we can see that ammonium is NH4 plus. We can take a look down here and see that Cl2 minus is chloride. We can also see that dromate for example is CR272 minus and that sulfate is going to be S SO42 minus. So all these polyatomic ions how are you going to memorize them? And believe me if you have these memorized then writing chemical formulas specifically turnary compounds or compounds that contain polyatomic ions is going to be easy for you. So, how can you memorize all these different polyatomic ions? Well, I'm going to show you a couple different ways that you can memorize these, and hopefully you'll start doing better on uh on naming and writing chemical formulas that contain these different polyatomic ions. So, it says right here that when naming polyatomic ions, remember one key rule is that 8 is going to be bigger than eight. So, what does that mean that 8 is bigger than eight? Well, it says right here that this means that a polyatomic ion that ends in eight will always have one more oxygen than its counterpart that ends in eight. Okay? And furthermore, it says a polyatomic ion with the prefix per will always have one more oxygen than its counterpart with an eight suffix. And last but not least, a polyatomic ion with the prefix hypo will have one less oxygen than its counterpart with an it suffix. So what the heck does all of this mean? Well, let's take a look at an example here. Let's take a look at chlorate. If we take a look at chlorate, its chemical formula is CL3 with a minus charge. Okay, so if we memorize what chlorate is, just Cl3 minus. Then when we're asked to determine what the chemical formula is for chlorite, that should be a piece of cake as long as we know that 8 is bigger than eight. And so what this means is is that the polyatomic ion that has an eight ending is going to have one more oxygen compared to the polyatomic ion with the it ending. For example, if we take a look at chlorate compared to chlorite, the only difference between these two polyatomic ions is that chlorate has one extra oxygen compared to chloride. For example, if we take a look down here at bromate, Br3 minus and bromite, Br2 minus. If we take a look at iodate, IO3 minus versus iodite IO2 minus. If we take a look at sulfate SO4 2 minus versus sulfite SO32 minus and if we take a look at nitrate right here NO3 minus versus nitrite NO2 minus you will notice in every one of these scenarios right here that the polyatomic ion that ends in 8 is going to have one extra oxygen compared to the polyatomic ion that ends in eight. Okay? So remember that eight is bigger than eight. Furthermore, if we take a look at the prefix per, what this means essentially is hyper. Okay, so if you're hyperactive, you are overactive. Okay, so if we drop the HY and just leave the per, what this really means is that we have one more oxygen compared to the polyatomic ion that ends in eight. Right? If we take a look at per chlorate compared to chlorate, this little purr or hyper means that the chlorate is going to have one extra oxygen on it. Okay? So per chlorate versus chlorate, you can take a look. For example, if we take a look at per bromate, it's Br4 minus. Whereas bromate is just Br3 minus. If it has per on it as a prefix, it's going to have one extra oxygen compared to its counterpart that ends in eight. For example, per iodate means it has one more oxygen compared to the uh its counterpart that has the eight suffix on it. For example, per sulfate right here has five oxygens whereas sulfate is just going to have four oxygens. And there is no per nitrate for reasons that we'll talk about in a later video. If you take a look at hypo, the prefix hypo means under. It means under. For example, a hypodermic needle goes underneath your skin, right? And so if we take a look at prefixes hypo or polyatomic ions that have the prefix hypo attached to them, what this means that this little polyatomic ion right here is going to have one less oxygen than chlorite. So if we know that chlorite only has two oxygens, then hypocchlorite is only going to have one. If we know that broomemite only has two oxygens, then we know that hypob bromite is going to have one less oxygen. And if we know that iodite, for example, has two oxygens, then hypoiodite is just going to have one oxygen. Okay? So understand this concept. So really all you have to do is memorize those polyatomic ions that end in 8 and you should be able to use these rules that 8 is bigger than eight and you should be able to use the uh rule of the prefix per and the prefix hypo to figure out the rest of those little polyatomic ions. And furthermore, keep in mind that any ion that ends in eyid is just going to be a single monotomic ion. It is not going to be a polyatomic ion. For example, chloride, bromide, iodide, sulfide, and nitride. These guys are here. These guys here are just monotomic. They're not polyatomic ions. Typically, polyatomic ions are going to end in eight. It have endings like that. And if it ends in iid, it's going to be a single monotomic ion. All right. So, I hope some of these rules eight is bigger than I uh make sense. Now, I hope you understand the the concept that per is a prefix. That means it's going to have one extra oxygen compared to the polyatomic ion counterpart that ends in eight. And I hope you understand that hypo means under. Okay? So if you have a polyatomic ion that starts with hypo, it's going to have one less oxygen than its polyatomic ion counterpart that ends in ike. All right? So this should help you out tremendously when you're memorizing these polyatomic ions. And so now that you have them memorized, you should be able to uh write the chemical formulas and uh for turnary compounds or compounds that contain polyatomic ions. If you like what you see right here, go ahead and click that little bomb in the bottom right hand corner and that will subscribe you to my channel. Also, feel free to leave any comments or questions in the comments section down below. And I hope you guys found this helpful.