Understanding Chemical Nomenclature Basics

Hey everybody, these are the video notes on nomenclature. We're going to start with what the word nomenclature means because you may or may not have heard it before. So Merriam-Webster defines nomenclature as the actor process or an instance of naming. Basically all we're learning about in this unit is how to name chemical compounds and then how to write their formulas. I have some bad news. Learning nomenclature is a lot like learning your multiplication tables. You've got to drill. You've got to practice. I'm sorry it's not going to be very fun. Like there's not going to be a lot of really fun neat activities. This is like a worksheet unit unfortunately because it's really one of those you got to put pencil to paper and just do it to do it. It will pay off though because when we start to write chemical reactions, if you have a really strong foundation in nomenclature, you're going to be rocking and rolling through later units. All right, so let's talk about the goals. You need to be able to name ionic compounds containing main group or transition metals, covalent compounds, acids and bases using international union of pure and applied chemistry, which is called IUPAC, that we need to be using their nomenclature rules. You also need to be able to write formulas of ionic compounds containing representative elements, transition metals, and common polyatomic ions. covalent compounds, and of course, acids and bases. You will show mastery when you can write formulas from names and write names from formulas. So just a brief aside, IUPAC, the International Union of Pure and Applied Chemistry, this is kind of like the ruling body for anything chemistry related. So anytime a new element gets named, IUPAC is the group that makes the final determination. They're kind of like the big ruling body of what naming and formula writing and stuff should look like. All right, so what is a chemical formula? Chemical formulas tell you the type and number of each element in a chemical compound. Molecular formulas will be the kind of formula that you're most used to seeing. It's just the normal formula, like what you would expect a chemical formula to be. That's what a molecular formula is. Again, it's still showing you the kind of number of atoms present in a particular compound. An empirical formula is going to show the elements in the compound as well, but instead of showing all possible atoms, it's just showing in the lowest whole number ratio. So if you have something like glucose, which is C6H12O6, this would be an example of a molecular formula, and we could reduce this down to CH2O. That would be the empirical formula. Obviously neither of these are going to tell us anything about the structure of a compound. Only Lewis structures, Vesper, and then like crystalline structures can really tell us what a compound looks like at the molecular level. This obviously right down here is the chemical formula for water. Just wanted to point out that the little numbers H2O, they have a name, they're called subscripts, just like H2O. You've heard me say before, so they're just called subscripts. All right, so we're going to start with ionic nomenclature. Starting with a review of cations and anions, you guys know that ionic compounds, ionic bonds, result in the electrostatic attraction between oppositely charged ions. So just to review, a cation is a metal that is going to lose electrons and gain a positive charge. An anion is a nonmetal that's going to gain electrons and gain a negative charge. And don't forget about those polyatomic ions. A polyatomic ion can be either an anion or a cation. The big trick is that it's going to be a group of elements that are bonded together and that carry an overall charge. So an example of a positive polyatomic ion is going to be ammonium NH4 plus. And an example of a negative polyatomic ion is going to be NO3. nitrate, and O3 with a minus one. A thing that I would like to point out to you is that up until this point we have told you that ionic compounds are always metals and nonmetals, and that's mostly true. Ionic compounds are actually more specifically cations and anions. So if we were to put these two things together into a compound, NH4NO3, this is still an ionic compound. because it's made out of ions. There's not a metal in here. So just be careful. Just because you don't see a metal does not necessarily mean that it couldn't be an ionic compound. It's got to be made out of ions. And then we come to the time where we talk about transition metals. We've told you that like anytime we've asked you to determine oxidation numbers, or we've had you draw bonding diagrams, that we weren't going to give you transition metals because we had to tell you the oxidation number for transition metals. And this is still true. The reason why is because transition metals are capable of forming more than one kind of cation. And the reason why is because they have valence electrons in their d orbitals. So when we lose... electrons from a transition metal, even though our outer s and potentially our outer p orbitals are lower energy than our d orbitals, we're still going to lose electrons from our s and p orbitals first before we touch any of the d orbitals. And so because you can lose different amounts of electrons depending on what kind of a bond you're making, it means you're going to see different oxidation numbers. I want to be very clear with you that you are not expected to memorize all the different kinds of cations that a transition metal could make. We're going to tell you directly, or we're going to give you information so that you can figure it out. We're not trying to trick you. All right, ionic compounds. So even though an ionic compound is made from charged particles, a positive ion and a negative ion, it is still electrically neutral. And that means that the total charge of an ionic compound is always equal to zero. Your net charge is equal to zero. This does not mean that your oxidation numbers will total to zero. Let me give you some examples. So first, do you remember your oxidation numbers? Just a reminder across the top, the first column is a plus one, plus two, plus three. plus or minus four, minus three, minus two, minus one, and then of course our noble gases are equal to zero. So some examples, sodium which is right here has an oxidation number of plus one, and oxygen which is over here has an oxidation number of minus two. This is the correct formula for sodium oxide. Our oxidation numbers do not equal zero. That's okay. The reason why it's okay is because we have two sodiums here. So we have a plus one and a plus one canceling out a minus two. What about for calcium chloride? Calcium's down here at the bottom with a plus two. Chloride's right here with a minus one. Again, our oxidation numbers do not equal zero. But because we have two of these, we have two negative ones. So this total... net charge cancels out. And then for magnesium, magnesium here is a plus two, oops, plus two, and we already said that oxygen is a minus two. In this case, they do cancel out. You've got to be careful. You're looking for a net charge equal to zero, not oxidation numbers that are equal to zero. This is one of the biggest points of confusion whenever people are assigning oxidation numbers. All right, so how do we write chemical formulas? The first thing that you're going to do is you're going to write the symbol for the element and its oxidation number. We always put the positive ion first by convention because IUPAC says so. All right, so we've got magnesium and we've got chlorine. Magnesium, Mg, where is it? Mg with a charge of plus two and chlorine Cl with a charge of minus one. So I've got Mg with a plus two. and I've got chlorine with a minus one. Again, metal first, positive ion first. Then we're going to crisscross the numbers and write them as subscripts without the signs. So I'm crossing and I'm dropping. Why am I doing this? You know how whenever you find least common multiples, you're looking for smallest numbers that will give you like go into both things. That's essentially what we're doing here. Like between two and one, what is the smallest number that will give you a two? It's two and one. So like we know that this is a one, how do we get it to a two? We need to multiply by two. So we're gonna cross and drop. This is just letting us balance our charges. Oops my symbol got moved, it should be over here. Okay so if there is a one charge, we're not gonna write it. So you just take the ones out. What happens if you have subscripts that are multiples? Well we can reduce them down. So we've got a plus four and a minus two. Clearly these are both divisible by two. So I'm going to cross and drive like I would. and then I'm going to reduce. So your plus four becomes a plus two when you cross and drop, and your two becomes a one. And then again we don't write our ones. What about polyatomic ions? So in this case we have calcium as a plus two and nitrate as a minus one. When we cross and drop we expect this one to drop down here and this two to drop here, but we have a problem. This three and this two They're butting up against each other. We don't want that. So how are we going to fix that? We use parentheses. So it's the exact same procedure. You cross and drop. And then because that was a 1, it goes away. But now I'm going to insert some parentheses. So we'll end up with CaNO3 2. Here's an example of a polyatomic ion that doesn't have parentheses. So this is a plus 1. When you drop this 1 back here, it's going to go away. And then we have a minus 3. When we drop that here, we're just going to see that 3. Oops, this 3 should be here. Sorry about that. So Na3PO4. All right, so let's practice. Barium and chlorine. Barium is Ba with a plus 2. Chlorine is Cl with a minus 1. I cross and drop, and I get BaCl2. Alright, how about rubidium and nitrogen? Rubidium is RB with a plus one. Nitrogen is N with a minus three. Cross and drop, and I get RB3N. Lithium and phosphate. Lithium is LI. Phosphate is PO4 with a charge of minus three. Cross and drop, I get LI3PO4. Then we come to this, this transition metal right here. Iron. and then it's got a parentheses next to it and it says 3. What do you think that parentheses is telling you? Iron is a transition metal. So this 3 in parentheses, this is actually telling you what the oxidation number is for that iron. So this iron in particular is Fe with a plus 3. Nitrate is going to be NO3 with a minus 1. We cross and drop we get Fe and this is a good example because we're dropping a 3 behind this nitrate, it means we need to have those parentheses to show that we have three nitrates. You want to think of polyatomic ions as units wholly unto themselves. Don't think of it as a nitrogen and three oxygens. Think of it as a single nitrate. We have three of them. That's why you need those parentheses. All right, then manganese. So manganese is MN, Mg is magnesium. Be very careful if you put Mg. I'm counting it wrong. They are not the same thing. So we've got manganese with a plus 4 and sulfur with a minus 2. All right, so a plus 4 and a minus 2, that means that we get to reduce. So when I cross and drop, I'm going to get Mn2s4, and when I reduce, I would get MnS2. All right, what if we're going backwards? Like what if we have the formula and we want to name the ionic compound? You're basically undoing the steps that you did. So start with the metal. We've got B-A-B-R-2. Obviously, the name of this metal is going to be barium. And then you're going to write the name of the nonmetal, but you're going to change that ending to I-D-E. So you know it's sodium chloride, I-D-E, ide. We're doing the exact same thing. So this bromine isn't going to stay bromine. It's going to become bromide. Barium bromide. We're done. It's very straightforward. Okay, but what happens if there's a polyatomic ion? Well, then it's really straightforward. Same thing. Name the metal. In this case, Ca is calcium. And then you just get to name the polyatomic ion. So who is NO3? Well, he's nitrate. Done. You don't even have to change the endings. And then we name these. Okay, so Na, this is going to be sodium. Then this is oxygen by itself. So we're gonna keep the oxygen part, but we're gonna change the ending so it's gonna become sodium oxide Oops, and then mg Cl2 mg is Magnesium Cl is chlorine, but we're gonna change that ending to ide So it's gonna be magnesium chloride and then we've got na2 co3 and a still sodium And then who is CO3? CO3 is a polyatomic ion. It's carbonate. No changes necessary because it's a polyatomic ion. Okay, let's layer some complexity in, naming ionic compounds. If a positive ion, meaning a metal, can have more than one oxidation number, you have to designate its charge in the name. We do this by putting the charge as a Roman numeral in parentheses between the positive and the negative ion. So I'm going to scroll back for a second to here. Remember this? Iron 3. And nitrate, we need to basically do this. So how do we do that? Why do we do that? We'll take a look at this. We've got Fe2O3 and we have FeO. Okay, let's name them. Fe is iron and O there, that's oxide. And then we've got Fe again here, also iron and an O again, also oxide. These are the same name. That's the point, is you have to tell me what kind of iron. These both exist in nature. We have to specify. So how do we do that? You're going to do it exactly the same way. You start by naming the ionic compound. So it is iron something, and then we change that ending on oxygen into ide. Now comes the fun part. I told you that we would either give you oxidation numbers. So the parentheses means we're giving you the oxidation numbers. Or we would give you a way to figure it out. You can reverse crisscross to find the charge of the iron. Like you know that oxygen's oxidation number is minus two. Where did this two come from? It came from crossing and dropping. So this three then, like where did that come from? We are going to uncross and undrop. So this started as a plus 3. So we would need to fill in, oops let me erase some of this so it's easier to see. So we bring that minus 2 up. If this is true, then what was the iron to begin with? Well, it had to be that plus 3. So when you fill this in, you fill in your 3. All right, how about for this one, FeO? We're gonna start by naming it. It's iron something and then we know we're changing the ending on oxygen to Ide. Okay, reverse crisscross to find the charge of the iron. Minus 1. Is oxidation number for oxygen actually a minus 1? No, it's actually a minus 2. So knowing that this is a minus 2, what does that mean your iron has to be in order to cancel out that minus 2? We've got 1 of each. It means it's got to be a plus 2. So we're going to plug in a 2 there. There are some exceptions, metals that don't need parentheses. Group one, so this is going to be everybody lithium down. Group two, this is going to be everybody beryllium down. And then group 3A, specifically, this is aluminum. There are some other exceptions. Zinc and cadmium are always plus twos. And then silver is always a plus one. And the reason why has to do with their electron configurations, which I'm not going to get into the details of right now. If you're really curious about it, I can answer that for you in class. So pretty much every single transition, inner transition, and like your other metals like lead and tin and antimony, these are the big ones, they have to have parentheses. A lead, we saw this on our electron configuration test, can be a pb with a plus 2 or a pb with a plus 4. Alright, so generally speaking, when you want to name an ionic compound, you're first going to name the positive ion. It's usually a metal. Not always, but usually. Does it need a Roman numeral? Yes or no? If the answer is yes, you're going to have to reverse crisscross and figure it out. If not, then you can ignore it. And then you're going to just name the negative ion. If it's a nonmetal, chlorine, fluorine, bromine, oxygen, whatever, you're going to change the ending to ide. If it's not a nonmetal, meaning it's a polyatomic ion, you just get to write it as is. All right, so let's practice. Na2s. Na, this is sodium. Sodium is in group 1. That means it's always a plus one, so we don't need Roman numerals. And then S is sulfur. I'm going to change the ending so that it's sulfide. CuCl2. Well, Cu is copper. Okay, copper is a transition metal. That means that we need to figure out what the oxidation number is for this copper. So I'm actually going to show you how I prefer to figure out oxidation numbers for transition metals. The way that I like to do this is to actually just assign the oxidation number that I know. I know what chlorine's oxidation number is. It's a minus one. And I've got two of them, which means I have a net total of negative two. Well, if all of your chlorine is equal to a negative 2, what does the copper have to be? It has to be a plus 2, and you can look and see that we actually unreverse, we uncrisscross, and we get that 2. So this is going to be copper 2, and then it's chloride, C-H-L-O-R-I-D-E, one of the number one words that you guys like to misspell. Okay, how about K2SO4? Okay, well, what is K? K is... potassium. And then we come to have to decide like, is potassium one where we have to give it parentheses? Potassium is also a group one metal. It's always a plus one. So we don't have to worry about parentheses. We can move on to this SO4. This is a polyatomic ion. His name is sulfate. We don't change the ending on polyatomic ions. We get to just write them as is. And then the last one, PbNO3 3. So we've got Pb, that's going to be lead. Lead is a post-transitional metal, an other metal. It can still have more than one oxidation number. I told you this right here. How do we deal with this? Well, I like to assign the oxidation number that I know. The oxidation number for the entire higher nitrate is a minus one. And the parentheses are telling me that I have three of them. So my total charge for all of these nitrates is a minus three. If I want my lead to be able to cancel that out and I've only got one of them, what does that mean that your lead has to be? It has to be a plus three. So we're going to have a lead three. And then again, we just write that anion. We don't have to change anything because it's a polyatomic ion, so lead 3 nitrate. All right, I'm going to stop there, and then I'll see you for covalent.

I have some bad news. Learning nomenclature is a lot like learning your multiplication tables. You've got to drill.

You've got to practice. I'm sorry it's not going to be very fun. Like there's not going to be a lot of really fun neat activities. This is like a worksheet unit unfortunately because it's really one of those you got to put pencil to paper and just do it to do it.

It will pay off though because when we start to write chemical reactions, if you have a really strong foundation in nomenclature, you're going to be rocking and rolling through later units. All right, so let's talk about the goals. You need to be able to name ionic compounds containing main group or transition metals, covalent compounds, acids and bases using international union of pure and applied chemistry, which is called IUPAC, that we need to be using their nomenclature rules.

You also need to be able to write formulas of ionic compounds containing representative elements, transition metals, and common polyatomic ions. covalent compounds, and of course, acids and bases. You will show mastery when you can write formulas from names and write names from formulas. So just a brief aside, IUPAC, the International Union of Pure and Applied Chemistry, this is kind of like the ruling body for anything chemistry related. So anytime a new element gets named, IUPAC is the group that makes the final determination.

They're kind of like the big ruling body of what naming and formula writing and stuff should look like. All right, so what is a chemical formula? Chemical formulas tell you the type and number of each element in a chemical compound. Molecular formulas will be the kind of formula that you're most used to seeing.

It's just the normal formula, like what you would expect a chemical formula to be. That's what a molecular formula is. Again, it's still showing you the kind of number of atoms present in a particular compound. An empirical formula is going to show the elements in the compound as well, but instead of showing all possible atoms, it's just showing in the lowest whole number ratio. So if you have something like glucose, which is C6H12O6, this would be an example of a molecular formula, and we could reduce this down to CH2O.

That would be the empirical formula. Obviously neither of these are going to tell us anything about the structure of a compound. Only Lewis structures, Vesper, and then like crystalline structures can really tell us what a compound looks like at the molecular level.

This obviously right down here is the chemical formula for water. Just wanted to point out that the little numbers H2O, they have a name, they're called subscripts, just like H2O. You've heard me say before, so they're just called subscripts. All right, so we're going to start with ionic nomenclature. Starting with a review of cations and anions, you guys know that ionic compounds, ionic bonds, result in the electrostatic attraction between oppositely charged ions.

So just to review, a cation is a metal that is going to lose electrons and gain a positive charge. An anion is a nonmetal that's going to gain electrons and gain a negative charge. And don't forget about those polyatomic ions.

A polyatomic ion can be either an anion or a cation. The big trick is that it's going to be a group of elements that are bonded together and that carry an overall charge. So an example of a positive polyatomic ion is going to be ammonium NH4 plus. And an example of a negative polyatomic ion is going to be NO3. nitrate, and O3 with a minus one.

A thing that I would like to point out to you is that up until this point we have told you that ionic compounds are always metals and nonmetals, and that's mostly true. Ionic compounds are actually more specifically cations and anions. So if we were to put these two things together into a compound, NH4NO3, this is still an ionic compound. because it's made out of ions.

There's not a metal in here. So just be careful. Just because you don't see a metal does not necessarily mean that it couldn't be an ionic compound.

It's got to be made out of ions. And then we come to the time where we talk about transition metals. We've told you that like anytime we've asked you to determine oxidation numbers, or we've had you draw bonding diagrams, that we weren't going to give you transition metals because we had to tell you the oxidation number for transition metals. And this is still true. The reason why is because transition metals are capable of forming more than one kind of cation.

And the reason why is because they have valence electrons in their d orbitals. So when we lose... electrons from a transition metal, even though our outer s and potentially our outer p orbitals are lower energy than our d orbitals, we're still going to lose electrons from our s and p orbitals first before we touch any of the d orbitals.

And so because you can lose different amounts of electrons depending on what kind of a bond you're making, it means you're going to see different oxidation numbers. I want to be very clear with you that you are not expected to memorize all the different kinds of cations that a transition metal could make. We're going to tell you directly, or we're going to give you information so that you can figure it out. We're not trying to trick you. All right, ionic compounds.

So even though an ionic compound is made from charged particles, a positive ion and a negative ion, it is still electrically neutral. And that means that the total charge of an ionic compound is always equal to zero. Your net charge is equal to zero. This does not mean that your oxidation numbers will total to zero.

Let me give you some examples. So first, do you remember your oxidation numbers? Just a reminder across the top, the first column is a plus one, plus two, plus three. plus or minus four, minus three, minus two, minus one, and then of course our noble gases are equal to zero. So some examples, sodium which is right here has an oxidation number of plus one, and oxygen which is over here has an oxidation number of minus two.

This is the correct formula for sodium oxide. Our oxidation numbers do not equal zero. That's okay. The reason why it's okay is because we have two sodiums here. So we have a plus one and a plus one canceling out a minus two.

What about for calcium chloride? Calcium's down here at the bottom with a plus two. Chloride's right here with a minus one. Again, our oxidation numbers do not equal zero. But because we have two of these, we have two negative ones.

So this total... net charge cancels out. And then for magnesium, magnesium here is a plus two, oops, plus two, and we already said that oxygen is a minus two.

In this case, they do cancel out. You've got to be careful. You're looking for a net charge equal to zero, not oxidation numbers that are equal to zero.

This is one of the biggest points of confusion whenever people are assigning oxidation numbers. All right, so how do we write chemical formulas? The first thing that you're going to do is you're going to write the symbol for the element and its oxidation number.

We always put the positive ion first by convention because IUPAC says so. All right, so we've got magnesium and we've got chlorine. Magnesium, Mg, where is it?

Mg with a charge of plus two and chlorine Cl with a charge of minus one. So I've got Mg with a plus two. and I've got chlorine with a minus one. Again, metal first, positive ion first. Then we're going to crisscross the numbers and write them as subscripts without the signs.

So I'm crossing and I'm dropping. Why am I doing this? You know how whenever you find least common multiples, you're looking for smallest numbers that will give you like go into both things.

That's essentially what we're doing here. Like between two and one, what is the smallest number that will give you a two? It's two and one.

So like we know that this is a one, how do we get it to a two? We need to multiply by two. So we're gonna cross and drop. This is just letting us balance our charges. Oops my symbol got moved, it should be over here.

Okay so if there is a one charge, we're not gonna write it. So you just take the ones out. What happens if you have subscripts that are multiples? Well we can reduce them down.

So we've got a plus four and a minus two. Clearly these are both divisible by two. So I'm going to cross and drive like I would.

and then I'm going to reduce. So your plus four becomes a plus two when you cross and drop, and your two becomes a one. And then again we don't write our ones. What about polyatomic ions? So in this case we have calcium as a plus two and nitrate as a minus one.

When we cross and drop we expect this one to drop down here and this two to drop here, but we have a problem. This three and this two They're butting up against each other. We don't want that. So how are we going to fix that?

We use parentheses. So it's the exact same procedure. You cross and drop. And then because that was a 1, it goes away. But now I'm going to insert some parentheses.

So we'll end up with CaNO3 2. Here's an example of a polyatomic ion that doesn't have parentheses. So this is a plus 1. When you drop this 1 back here, it's going to go away. And then we have a minus 3. When we drop that here, we're just going to see that 3. Oops, this 3 should be here. Sorry about that.

So Na3PO4. All right, so let's practice. Barium and chlorine. Barium is Ba with a plus 2. Chlorine is Cl with a minus 1. I cross and drop, and I get BaCl2.

Alright, how about rubidium and nitrogen? Rubidium is RB with a plus one. Nitrogen is N with a minus three.

Cross and drop, and I get RB3N. Lithium and phosphate. Lithium is LI.

Phosphate is PO4 with a charge of minus three. Cross and drop, I get LI3PO4. Then we come to this, this transition metal right here.

Iron. and then it's got a parentheses next to it and it says 3. What do you think that parentheses is telling you? Iron is a transition metal. So this 3 in parentheses, this is actually telling you what the oxidation number is for that iron.

So this iron in particular is Fe with a plus 3. Nitrate is going to be NO3 with a minus 1. We cross and drop we get Fe and this is a good example because we're dropping a 3 behind this nitrate, it means we need to have those parentheses to show that we have three nitrates. You want to think of polyatomic ions as units wholly unto themselves. Don't think of it as a nitrogen and three oxygens.

Think of it as a single nitrate. We have three of them. That's why you need those parentheses. All right, then manganese. So manganese is MN, Mg is magnesium.

Be very careful if you put Mg. I'm counting it wrong. They are not the same thing.

So we've got manganese with a plus 4 and sulfur with a minus 2. All right, so a plus 4 and a minus 2, that means that we get to reduce. So when I cross and drop, I'm going to get Mn2s4, and when I reduce, I would get MnS2. All right, what if we're going backwards?

Like what if we have the formula and we want to name the ionic compound? You're basically undoing the steps that you did. So start with the metal. We've got B-A-B-R-2. Obviously, the name of this metal is going to be barium.

And then you're going to write the name of the nonmetal, but you're going to change that ending to I-D-E. So you know it's sodium chloride, I-D-E, ide. We're doing the exact same thing. So this bromine isn't going to stay bromine. It's going to become bromide.

Barium bromide. We're done. It's very straightforward.

Okay, but what happens if there's a polyatomic ion? Well, then it's really straightforward. Same thing. Name the metal. In this case, Ca is calcium.

And then you just get to name the polyatomic ion. So who is NO3? Well, he's nitrate. Done. You don't even have to change the endings.

And then we name these. Okay, so Na, this is going to be sodium. Then this is oxygen by itself. So we're gonna keep the oxygen part, but we're gonna change the ending so it's gonna become sodium oxide Oops, and then mg Cl2 mg is Magnesium Cl is chlorine, but we're gonna change that ending to ide So it's gonna be magnesium chloride and then we've got na2 co3 and a still sodium And then who is CO3?

CO3 is a polyatomic ion. It's carbonate. No changes necessary because it's a polyatomic ion.

Okay, let's layer some complexity in, naming ionic compounds. If a positive ion, meaning a metal, can have more than one oxidation number, you have to designate its charge in the name. We do this by putting the charge as a Roman numeral in parentheses between the positive and the negative ion.

So I'm going to scroll back for a second to here. Remember this? Iron 3. And nitrate, we need to basically do this.

So how do we do that? Why do we do that? We'll take a look at this.

We've got Fe2O3 and we have FeO. Okay, let's name them. Fe is iron and O there, that's oxide. And then we've got Fe again here, also iron and an O again, also oxide. These are the same name.

That's the point, is you have to tell me what kind of iron. These both exist in nature. We have to specify. So how do we do that? You're going to do it exactly the same way.

You start by naming the ionic compound. So it is iron something, and then we change that ending on oxygen into ide. Now comes the fun part. I told you that we would either give you oxidation numbers.

So the parentheses means we're giving you the oxidation numbers. Or we would give you a way to figure it out. You can reverse crisscross to find the charge of the iron.

Like you know that oxygen's oxidation number is minus two. Where did this two come from? It came from crossing and dropping. So this three then, like where did that come from? We are going to uncross and undrop.

So this started as a plus 3. So we would need to fill in, oops let me erase some of this so it's easier to see. So we bring that minus 2 up. If this is true, then what was the iron to begin with?

Well, it had to be that plus 3. So when you fill this in, you fill in your 3. All right, how about for this one, FeO? We're gonna start by naming it. It's iron something and then we know we're changing the ending on oxygen to Ide.

Okay, reverse crisscross to find the charge of the iron. Minus 1. Is oxidation number for oxygen actually a minus 1? No, it's actually a minus 2. So knowing that this is a minus 2, what does that mean your iron has to be in order to cancel out that minus 2?

We've got 1 of each. It means it's got to be a plus 2. So we're going to plug in a 2 there. There are some exceptions, metals that don't need parentheses. Group one, so this is going to be everybody lithium down.

Group two, this is going to be everybody beryllium down. And then group 3A, specifically, this is aluminum. There are some other exceptions. Zinc and cadmium are always plus twos. And then silver is always a plus one.

And the reason why has to do with their electron configurations, which I'm not going to get into the details of right now. If you're really curious about it, I can answer that for you in class. So pretty much every single transition, inner transition, and like your other metals like lead and tin and antimony, these are the big ones, they have to have parentheses. A lead, we saw this on our electron configuration test, can be a pb with a plus 2 or a pb with a plus 4. Alright, so generally speaking, when you want to name an ionic compound, you're first going to name the positive ion.

It's usually a metal. Not always, but usually. Does it need a Roman numeral? Yes or no?

If the answer is yes, you're going to have to reverse crisscross and figure it out. If not, then you can ignore it. And then you're going to just name the negative ion.

If it's a nonmetal, chlorine, fluorine, bromine, oxygen, whatever, you're going to change the ending to ide. If it's not a nonmetal, meaning it's a polyatomic ion, you just get to write it as is. All right, so let's practice.

Na2s. Na, this is sodium. Sodium is in group 1. That means it's always a plus one, so we don't need Roman numerals. And then S is sulfur.

I'm going to change the ending so that it's sulfide. CuCl2. Well, Cu is copper.

Okay, copper is a transition metal. That means that we need to figure out what the oxidation number is for this copper. So I'm actually going to show you how I prefer to figure out oxidation numbers for transition metals.

The way that I like to do this is to actually just assign the oxidation number that I know. I know what chlorine's oxidation number is. It's a minus one. And I've got two of them, which means I have a net total of negative two. Well, if all of your chlorine is equal to a negative 2, what does the copper have to be?

It has to be a plus 2, and you can look and see that we actually unreverse, we uncrisscross, and we get that 2. So this is going to be copper 2, and then it's chloride, C-H-L-O-R-I-D-E, one of the number one words that you guys like to misspell. Okay, how about K2SO4? Okay, well, what is K? K is... potassium.

And then we come to have to decide like, is potassium one where we have to give it parentheses? Potassium is also a group one metal. It's always a plus one.

So we don't have to worry about parentheses. We can move on to this SO4. This is a polyatomic ion.

His name is sulfate. We don't change the ending on polyatomic ions. We get to just write them as is. And then the last one, PbNO3 3. So we've got Pb, that's going to be lead. Lead is a post-transitional metal, an other metal.

It can still have more than one oxidation number. I told you this right here. How do we deal with this? Well, I like to assign the oxidation number that I know.

The oxidation number for the entire higher nitrate is a minus one. And the parentheses are telling me that I have three of them. So my total charge for all of these nitrates is a minus three.

If I want my lead to be able to cancel that out and I've only got one of them, what does that mean that your lead has to be? It has to be a plus three. So we're going to have a lead three.

And then again, we just write that anion. We don't have to change anything because it's a polyatomic ion, so lead 3 nitrate. All right, I'm going to stop there, and then I'll see you for covalent.

Transcript for:Understanding Chemical Nomenclature Basics

Transcript for:
Understanding Chemical Nomenclature Basics