Let's look at how to write names for compounds like these that are made of two nonmetals. The nonmetals are the elements to the right of the staircase on the periodic table. Now, compounds like these that are made of a nonmetal and another nonmetal, two nonmetals, are called covalent or molecular compounds. And that's because the elements that are in them are held together by covalent bonds, and they're held together in groups. called molecules.
Now the way we name covalent or molecular compounds is different from how we name ionic compounds. Ionic compounds contain a metal and a non-metal. The metals are the elements here on the periodic table and I've written in some of the most common.
Some examples of ionic compounds and of how we name them are things like calcium fluoride and iron oxide. So If you have to name a compound, the first thing you want to do is figure out what type of elements are in it. If the compound is made of a metal and a non-metal, it's an ionic compound. I have a whole bunch of videos on how to name ionic compounds and how to write formulas for them. If you need to name a compound that's made of a non-metal and another non-metal, well that's a covalent or molecular compound, and naming these is what this video is going to focus on.
Okay, here's our first chemical formula. N2O3. It's made of two nonmetals. We're going to write a name for it following these steps. So here's the first one.
It says for the first element, start with the element name. When I'm talking about the first element, I'm talking about the order that these elements are in in this chemical formula. So the first element here is nitrogen, N.
So it says start with the element name. Okay, so I'm going to put nitrogen down. That's the element name here. Now for the second element.
So that's this here, oxygen. For the second element, start with the IDE name. Now the IDE name is the version of the element name that ends in IDE. These are actually the same names that we use to name negative ions. So we've got oxygen here.
We're going to use its IDE name, which is oxide. Okay, so we got nitrogen and we got oxide. Now, use prefixes to show how many atoms of each type there are. The prefixes, here's a list of them, are like these little tags that we put on the front of each name to tell us how many atoms of each type we have.
So, N2, we got two nitrogens, which means that we want to use this prefix for two. Di, so put that in front of the element name. Di nitrogen. Now, O3, which means that we have three oxygens. So, I'm going to use the prefix tri.
tri here and write that in front of oxide and so the name for this compound is dinitrogen trioxide we put the element name here we put the ide name here and then we use the prefixes to indicate how many atoms of each type we have let's look at a few more examples p4 s10 okay for the first element we'll start with the element name p is phosphorus. If you didn't know that, you could look it up on the periodic table. For the second element, that's S here.
Start with an IDE name. So S is sulfur, and its IDE name is sulfide. So those are the two names. Now we're going to use prefixes to show how many atoms of each type we have. We got P4, so that means we have four phosphorus atoms.
So four is tetra. We use the tetra prefix. Tetra. And then for sulfide, we got 10. So we'll use this prefix, deca, deca.
So the name of this compound is tetraphosphorus decasulfide. Let's move on. We're going to add a couple more steps to deal with more complex formulas.
Here's the next step that we're going to talk about. Do not use mono on the first element. I'm going to show you what this means by working through naming this formula.
We'll start it off just normally. So for the first element, start with the element name. That's carbon.
And then the second element, which is fluorine, we use the IDE name, which in this case is fluoride. Okay, now we get to the prefix part, and this is where things change a little bit. So it says do not use mono on the first element. Carbon here, we only have one of them.
So you might want to use mono and put it in front of you. That would be a perfectly logical thing to do. But for whatever reason we don't use mono on the first element if there's just one of them.
We just Leave it like this. You don't put anything there. So we have one carbon.
We're just going to call it carbon. And then for fluorine here, in front of fluoride, I'll put the prefix just like I would any other time. So I have four of these fluorines, so I'm going to call it tetra, tetrafluoride.
So carbon, tetrafluoride, not monocarbon tetrafluoride, just carbon tetrafluoride is how we name this. because if you've got just one of the first element, you don't use anything. PCL5, let's name this. So P, the first element, is phosphorus.
Cl, the second element, is chlorine. And chlorine's IDE name is chloride. So there it is.
Now we get to the prefixes. Phosphorus here, we only have one of them. So we're not going to use mono here. We're just going to keep it as phosphorus. And chlorine, we have five of those.
So we're going to use penta here as the prefix. So it's going to be penta, pentachloride. And phosphorus pentachloride, not monophosphorus pentachloride, just phosphorus pentachloride is how we name this. Now there's one more step that we're going to add. I'm going to talk about that next.
Okay, there's one more step to keep in mind. And I'm going to show it to you as I work through this example. Okay, Cl2O7.
The first element here, Cl, is chlorine. And... O here is oxygen. Its IDE name is oxide.
Okay, so now the next thing I'm going to do is I'm going to use these prefixes. So I got two chlorines. So I'm going to use di, di for two up here.
And then oxide. I got seven of those. So I'm going to use the prefix hepta.
Now try saying this compound. We got dichlorine. chlorine, heptoxide, here that heptoxide thing, it's kind of awkward to pronounce.
So to prevent us coming up with these really weird names, there's one more rule. And that's that if you have a O or O turn it into O, here's what that means. We got this heptoxide here.
So to make this easier to pronounce, we turn the AO that we see right there into just an O. So I'm going to get rid of that A. I'm going to get rid of that A, and I'm going to turn this compound name into chlorine heptoxide.
So not heptoxide, but just heptoxide. So you get rid of that A if it's next to an O there. Let's do one more.
P4, O6. So the P, phosphorus, is our first element. And then O, we got oxide.
That is an ID name for oxygen here. All right, now. Let's use the prefixes. Switch to our prefix table here. We have 4-phosphorus, so we're going to use the tetra prefix.
So tetra, tetraphosphorus. And then for oxygen, we have six of those, so we're going to use hexa here. And just as before, we end up with this awkward name, hexoxide.
We get an AO, so we're going to get rid of this A here. Shoop. Ah, I always, like, knock that name out of the way. hexa oxide and that turns it into tetraphosphorus hexoxide you know i forgot to circle the name in the last one and this is just so satisfying so i did it really slowly to make up for the fact i i didn't circle the last one so we get rid of this uh we get rid of this a here tetraphosphorus hexoxide so i want to do one more example that pulls in examples of all of this it's like a good review for all of these things here's our last formula this is a really good review it's just c o so the first element is carbon the second element is oxygen its ide name is oxide okay so now for the prefixes carbon we've only got one of them so remember don't put anything in front of it we just call it carbon but we have one o and if you have one of the second element you do use a prefix so we use the mono prefix here So mono. Now monoxide gives us the same kind of weird pronunciation thing.
It gives us an OO here. So we're going to get rid of this. Oh, I'm going to try to not knock this name out here.
Oh, just a little bit. Really good. And we call this, we change the name from monoxide to carbon monoxide, which is probably something that you've heard of before. Here's just some quick information about how we change these prefixes to avoid an awkward pronunciation problem. We only really have this problem with oxide because it begins in O.
And so we get rid of the O here in mono and we get monoxide. Then we don't have to worry about di or tri because they don't end in A or O. And then for all of these others, 4 through 10, we get rid of all of these A's.
So we get tetroxide, pentoxide, hexoxide, heptoxide, octoxide, nonoxide, and decoxide. So here's how we name covalent or molecular compounds with two non metals. Just follow each of these steps. One thing to keep in mind this mono for the first element really confuses a lot of people.
So remember not to use mono if there's just one of the first element. Keep this in mind. Try to prevent yourself from writing names that have really awkward pronunciations with AO or OO. Turn it into O. Keep these things in mind.
You should be all set.