IUPAC Naming - Video Tutorials & Practice Problems
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In chemistry, every single molecule needs a unique name. We can’t have two molecules with the same name or that would get super confusing! For this, we use IUPAC nomenclature.
Alkane Nomenclature Overview
1
concept
The different parts of an IUPAC name
Video duration:
3m
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Video transcript
So what I want to do is I want to introduce the concept of al que nomenclature. And if we learn this, then we're gonna be able to use this systematic method in order to name a bunch of other molecules later. All right, so a little bit of a history lesson, really quick. Before 1919 chemists had no uniformed way toe name molecules, so they would basically just make up common names on the spot. That was that's what it was called. It was called a common name. Alright, so literally. Some chemists would name molecules after their dog after their ex wife after like something they saw, like in the movies, I don't know. And it got really confusing because there were a ton of names that people started having to memorize as people started discovering more molecules. So 1919 the AIPAC convention gets together and they saseidx. Hey, this is getting out of hand. This is getting crazy. We need to figure out a systematic method to name all these molecules, and that's when I pack Nomenclature was born. So the way that it basically works is that there's four different things that we look at for AIPAC nomenclature. Here, you'll see that what I'm giving you is an alcohol. Okay, so this is actually a little bit beyond the scope of what we're gonna talk about for this first set. We're just gonna talk about all canes. But I'm just going to show you that what we do is we break up a big molecule into small into more manageable pieces. Um, the first and most important thing that we always look at is the root. Okay, the roots. This is also called Let me write it in black. This is also called the parent chain. Okay. Called the root chain or the parent chain. And that's usually just gonna be I'm gonna go through these rules in a second. That's usually just gonna be your longest chain. Okay. All right. So, as I said, I'm not going over the rules just yet. I'm just I'm just helping you guys see, like the differences between these different things, different parts of the name. So then what they said is Okay. Well, not everything is on the route chain, though. There's other things coming off of it. So what they said is that anything that's coming off of it. They're going to call that a substitution. Okay, so substitution is just a branch. Okay, So if you ever see that, that word just means there's a branch coming off the chain. So in this case, I have a carbon that is not on the on the black line, and it's just sticking out. So that means that would be a branch. Okay, but then if we have branches, we need to know where is that branch? Because I can't just say there's one branch. Where is it? Is at the end. Is it in the middle? So we're gonna need locations for those branches. So another part of the name is the fact that I need to have number locations. I'm just gonna put numbers in order to know where those branches are. Does that make sense? So far, So basically, I have a main chain. I have things coming off of it and then have to say where those things are easy. So far, it's kinda like giving someone directions. Okay, You have to say, What's the street? What's the zip code? All its different stuff. All right, then we have this one last thing called the modifier. The modifier is just basically the functional group. Okay, I'm just gonna put f g for functional group. And the functional group determines the actual basically, a Suffolk six of the route. Okay, so you're gonna add a Suffolk's at the end, depending on what the functional group is. And that's gonna tell you what kind of molecule your molecules actually gonna react as. Okay. So, like I said, this Suffolk's has to do with the function of the molecule. Does that make sense? So, like I said, this is beyond the scope of naming this molecule is beyond the scope of what we're doing right now. But I just want to show you an example of everything okay. Of all the different components.
Basically there are 4 different parts to naming most molecules:
The Root or Parent Chain (this tells us about overall chain length)
Modifiers (tells us what functional groups are attached to the chain)
Substituents (tells us about what is branching off that chain)
Numerical Locations (tells us where those branches are)
Alkane Prefixes
2
concept
Learning Alkane Prefixes up to 12 Carbons in Length
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1m
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I just wanna look at this chart here. This chart is going to be like your cheat sheet for the different route names or parent names that you need to know. Now, some professors don't require you to know all the way up to 12. Some professors will have you ended eight. Some professors have you ended? 10. So just it's up to your professor. I'm just doing 12. Just to be thorough. Just in case you're professor like wants, you know all 12. So let's go ahead and do these one at a time. What would be the prefix for one carbon and it would be meth. Okay, so we have we have meth, then the second one. So two carbons would be f Okay. And you guys maybe start saying these with me because maybe, you know some of them from gen camera. You learn them in class, then we have a probe. Okay, then we have Butte. Okay, then we have pent. Then we have hex. All right, Now this one gets people Sometimes when you started seven. It's not cept it's helped. Okay? Helped. Oct nine deck. Okay, so those aren't so bad now. 11 and 12 are a little bit weird. 11 is going to be soon deck, so that one actually makes sense. It's like one and 10 and then 12 is doe deck. Okay. And I don't know if if you could just somehow remember that that's one and two plus 10 then that will help. Okay, so those are the prefixes that you need to know these air, they're going to be the ones that tell you basically how long that route or parent chain is?
Memorizing sucks, I get it. But unfortunately this is something you’re just gonna have to remember. Not all professors will make you memorize all 12 so check with your professor to figure out how many you need to know!
IUPAC Alkane Naming Rule #1
3
concept
Naming the root chain
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1m
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There's another parts of this rules, and let's go back up to that. What if you have two different pathways to different chains that are of equal length? Okay, So if there's how, if you have a tie between longest chains okay, then what we're gonna do is we're going to choose the chain that gives the most substitue INTS. Okay, So what that means is, if you have the choice between two, let's say 10 carbon chains. One of them gives you three substitutes. If you follow it, Dylan gives you four. You're gonna pick the chain that gives you four substitutes. Why would that be? That actually sounds more complicated. The reason is because if you can break down your substitutes into more, the chances are more likely that those substitutes will be smaller and easier to name. Okay, so it's actually a good thing. As an organic chemist, it's good for me to have a bunch of small substitutes that are easy to name instead of having ah, few really big substitutes that air terrible to name. Okay, so does that make sense so far? That's what we're starting. That's rule number one. Let's go ahead and move on to the next rules.
Remember, if there is a TIE between two chains of equal length, go with the chain that gives the MOST substituents!
IUPAC Alkane Naming Rule #2
Now we know the length of the root chain, but nothing else! We need to determine which carbon gets the “1” location.
4
concept
How to determine the direction of the root chain
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1m
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So Rule number two once you already figured out the longest chain, is that we have to decide the direction of that chain. And the way we do that is to start from the closest Substitue Int. Okay, so remember that substitue. It just means branch, Alright? And what that means is that I want my branch numbers to be as small as possible. Remember that each branch needs a location number. So in order to get those numbers as low as possible, I want to start from the side. That's gonna have the closest branch, then it's kind of the lowest location possible. Okay, So unlike if you're reading you always in the English language, you always read from left to right. It's not the same in organic chemistry. In organic chemistry, you can read from any direction as long as that's the direction that gives you the smallest numbers in terms of location. Okay, so then there's a few additional rules because this happens a lot. How if there's a tie between substitutes meaning that on one side you get to the first substitute in three carbons on the other side. You also get to the first substitution in three carpets. Okay. Well, then we're gonna compare the next closest substitutes. Okay, So then what that means is that I would say, Okay, both of these air tied. Let's move on to the next set. And maybe there's gonna be a difference there. Okay, But then there's even, like a more nightmare situation. Which is? What if there's still a tie? What if all throughout the subsistence are exactly symmetrical locations? Then what we would do is we would determine the direction. Meaning which side gets the number one position? Is that the left or is it the right or is it the bottom of the top using alphabetical order? Back tickle order.
Start numbering the root chain starting from the closest substituent
If there is a tie between locations, compare the locations of the next substituents
If there is STILL a tie between ALL locations, decide using alphabeticalorder.
The key here is to get the lowest numbers possible for ALL of your locations (at least for now). Now give it a shot by yourself with these examples!
5
example
Name the longest carbon chain
Video duration:
4m
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Video transcript
So what I want to do is just do this first one as a worked example between us. So it says here name the longest carbon chain and determine the direction of the route chain. I know that could be difficult to relate, Thio. So first of all, let's figure out what the longest carbon chain is. Go ahead and think about it for a second, and then I'll get back to me. All right, so there were actually a few different longest chains. Alright, Um, for example, I could have had on this be one of the chains. That would be how maney carbons. That looks like it's gonna be seven carbons. Are you cool with that? But I could have also had this be one of my longest chains. Do you agree that one would also be seven carbons? Oops. So what I'm doing right here is I'm actually still going through Rule number one. I haven't even gotten to two yet to his direction. One is just which chain is going to be the longest one is gonna be my route chain. So, what do you guys think? The green area means? That that's gonna be the chain, no matter what. But should I go to the yellow go? Should I go up or should I go down to the blue? There is actually a rule to determine this. I said if there's a tie between two different ways that you could make a chain the longest chain, how do you determine which one is the winner? The way you determine is by the one that gives you the most substitue INTS. Okay, so what I wanna do is I wanna erase both of these, or I wanna erase one, and we're going to see how many substitutes each one gives. So if I have the yellow chain, how many substitutes do I have total? I have just one substitute went, Remember that a substitute just means a branch. So I just have one thing that's not on the yellow. Does that make sense? One thing branching off, so I'd call that one. All right, now we're gonna do is we're going to erase the yellow and I'm gonna draw the blue. So now if I have the blue chain, how many substitue INTs do I get? Well, I'm gonna erase the red just in case you were confused. So for the blue chain, how many things do have sticking off of the blue chain? Actually, too, I have something here and I have something there. Okay? And what that means is that one of these is going to give me more substitutes and it's gonna be the blue. So this is actually my longest carbon chain right here. So my route is going to be hep Dane, and it's gonna be that particular heft ain cool. So now all we have to do is determine the direction. Direction means simply, Is this gonna be the first carbon? Or is this gonna be the first carbon? Let me use different colors. So is the blue gonna be my first carbon? Or is the red gonna be my first carbon? Do you now want to rule number two? So do you remember how to decide that? What we would do is we would go start from the closest substitue int. Okay. And the closest substitue in if I go to blue, I would have to go to 2345 My first substitution starts at five. If I start numbering from the blue direction. Okay, so five is the number to be. Now if I start numbering from the red direction I get to to and I already have a substitution. Do you see that? So I get to the second carbon. I already have a branch coming off. So which of these is going to give me the lower number? Which of them is gonna be the one that gives me the direction? And it's gonna be read. So I'm gonna erase the blue. The brute blue is wrong. And what that means is that this is gonna be later on, when I have to name this molecules we're not gonna do yet. We're not there yet. But later on, when you have to name this, this is gonna help me. Because now I'm gonna have substitutes at the two and at the three. And that is way better than having substitutes at the five. And at the six, which would have been the blue direction. Does that make sense? So the direction was this way, and that is the end of the question. Okay, so you guys did an awesome job now what I want to do because I want you guys to do this one on your own, So go ahead and try to do the entire thing and then go to the next video when you're done.
6
example
Name the longest carbon chain
Video duration:
2m
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Video transcript
All right, so let's solve this one. So, basically, I had a few different options. I could have maybe taken the yellow route. I've done this as my longest chain. Um, were there any other longest chains that I could have made? Actually, no. There was no other way to make a six carbon chain. Now, what you guys might be thinking is, Well, Johnny, what if I did it like this? The blue direction like that. Wouldn't that be a little bit different? And actually, no, that would be the same exact chain. And the reason is because I'm just gonna race this notice that both of these groups at the ends are both identical and both of the groups that the ends are identical here. Okay, So what that means is, it doesn't really matter if you pick the bottom one of the top one. That's still the same thing. So if you drew your longest chain like this, that's fine. That's the same thing as drawing this, okay? It just it doesn't really matter as long as you have those six in order. Because, like I said, the groups on both ends are exactly the same. Okay, cool. So that's the first thing. So that actually the first part Rule number one was easy. Figure out the longest chain was easy. Now we just have to figure out the numbering in K or the direction. So should this be my number one, or should this be my number one? Okay, So should I have read is my one or blue is my one. So what I would do is I would say Okay, let me start counting and see when I get to my first substitue int. So for red, I would get to to and I would already reach a substitue int. You guys agree with that? Cool. So that's hard to beat. Red Red Looks like red might win. Now let's look at what the blue side I get to two and two is also substitue int. So wait, what does that mean? Does that mean we give up? No, it does not mean that it means that there's a tie. So I have to go to the next rule. The next rule says Okay, well, if there's a tie, then move to the next substitutes. So that means that now I have to keep counting from red and say How long did it take me to get to the next substitute? Well, three and then four would be the next one. Okay, so I have from four. Is the number to beat now with Blue three. I'm already there. So which one's gonna win Blue? So it turns out that this is gonna be a six carbon chain. So this is gonna be heck saying and it's gonna be numbered in this direction. Does that make sense with this being my one and this being my six is that cool? Guys, Hopefully that made sense. Alright. Got school ahead and move on to the next rule.
If you got this one wrong, don’t worry too much. You’ve got plenty more chances to nail this.
IUPAC Alkane Naming Rule #3
So we know the length and direction of the root chain, which is great. But if there are ANY branches on this chain, we need to name those too.
P.S. The term “substituent” is just a nerdy word for a “branch”.
7
concept
How to identify and locate branches (substituents)
Video duration:
3m
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Video transcript
All right. So this is the page where we really get into naming, Okay? We're gonna learn how to put everything together and make a full all cane name by the end of this page. So Rule number three this is after we've already identified the longest chain and the direction of that chain Rule number three, is to designate designate numerical locations of substitue INTs. Okay, so what that means is that I'm gonna want to actually say Okay, Is this substitution on two? Or is it on three? Okay. Now, when there's more, more than one identical substitutes, let's say that I have to one carbon groups instead of naming them both individually, we wanna cluster them together to save some space and the save some time. So we're gonna do is we're gonna use prefixes, thes prefixes. They're gonna tell us how many of that type of substitute we have. So the prefix for two is die. The prefix for three is try, and the prefix for four is tetra. Okay, So die tryin, tetra. And when we do represent these chains, these branches, they aren't true al canes. And the reason is because they're always gonna be missing an H because of the fact that they are on a branch. So, for example, let me just give you an example. Here I have ah, long chain, and then they have a two carbon chain coming off of it. Okay. The form, the molecular formula of this to carbon chain is ch two ch three. Okay. The molecular formula for a normal to carbon chain is ch three ch three. That would be if it was just by itself. It would just be a stick. Does that make sense? The name of that Al Cain, the red one right here. The name of that one, if it was just on its own, would be what all came prefixes. It would be ethane. Does that make sense so far, But notice how the molecular formula is slightly different. Here I have a three, but when it's a substitute or branch, it has a two. So this is not you can't just call it ethane. Instead, what we're gonna do is we're gonna represent it using the ah y el Suffolk six. So basically al Keynes become Al kills. And I told you, is this already? Earlier on when We're talking about functional groups that if you have a chain coming off, you put a y l. Suffolk's for the for the Al cane. Okay, so that means that this would be called Ethel, not ethane. Okay, the actual the actual branch off right there. Okay. And that means that we're missing one hydrogen. Okay, so what I want you guys to do is we're gonna put this all together. We're not going to name the entire thing yet, but we're pretty much going to get all the pieces. I want you guys to name the root chain, determine the direction of the route chain, and then identify and locate all the substitutes. So we're going to do this as a work to practice. So we're gonna do this together, But just go ahead and try to solve it on your own. And don't go to the next video until you're done with it.
NOTE:Alkane substituents require a “-yl” suffix to indicate that they are a branch! (i.e. ethane becomes ethyl).
8
example
Name the longest carbon chain and substituents
Video duration:
2m
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Video transcript
Alright, guys. So hopefully you got that. The longest chain was actually this one right here. I know that could be tricky to visualize because you're not used to thinking of curving around stuff. You're used to seeing things just from left to right and things in a straight line. But the longest chain just is the longest continuous chain of Adam. So that would be that swirly one right there. Okay, so how many is that? That looks like 123456789 So this is gonna be that the root equals non ing quote that so far, now we have to determine the direction. So this one's actually pretty easy. This is my one in blue. This is my one in red. Which one is gonna be the direction Which one's gonna be a better direction? And obviously it would be the blue Okay, Because the blue I'm going to get to my first substitution at the three position words with the red. I wouldn't get to my first substitute until the five position. Okay, so that was just That was just a loser. Red sucks. Okay, so now I have my numbering determined. Now I have to identify and locate all the substitue INTs. The easiest way to do this is just to number the entire chain. So I'm just going to say seven he nine. How many subsistence do I have? I have to. I have one on the three and one on the five. Okay, So the way we're actually gonna name these, so I'm just gonna put here subs. Okay, now I'm getting hungry. Um, so we're gonna put these is by naming the out the location with a hyphen, and then we're going to say with the, um, what the actual alcohol group is. I'm gonna teach you more about this on as you move down the page. But I'm just telling you this right now. So one of the substitutes would be three hyphen metal, by the way, if you didn't add the hyphen, that's totally fine. Because I haven't taught you that yet. Okay, but just, you know, if you just put three metal, that's fine, but it's actually three hyphen metal. That would be one substitue int. Another substitution would be five hyphen. Ethel, does that make sense? Because I haven't Ethel group on the five and a method upon the three awesome
Sick job! We’re getting closer to fully naming these guys.
IUPAC Alkane Naming Rule #4 and #5
Now we have all the pieces we need to name most alkanes, but we need to work on our formatting! Chemists are surprisingly analytical making sure all your commas and numbers are in the right place.
9
concept
Proper name ordering and punctuation
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1m
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So now we pretty much have all the pieces that we need to put a name together. I have seen to teach you to additional rules. All right, so let's go ahead and work on that. So the next rule is that now we have all the pieces. You just have to figure out how to make this big name. What we're gonna do is we're gonna name substitue INTs in alphabetical order. Okay, So remember, substitutes would be like Ethel metal. I don't care about which one's bigger. I just care about which one has the lower number in the A lower letter in the alphabet. Okay. And also prefixes don't count towards this. So if I have a dime, Ethel or try metal, I don't actually count de as the I don't Count D as the alphabetical order. I would count metal m as the alphabetical order. Okay, so remember that prefixes don't count, then finally, this is the part that I was saying. We're gonna use commas, two separate numbers from numbers and we're gonna use dashes or hyphens. Whatever you want to say to separate letters from numbers. Okay, so up here, why did we use a dash or hyphen. Okay, Because there's a number and a letter, and then we would use a dash because there's a number in a letter next to each other. But if it was a number in a number, I would use a comma. Okay, The biggest thing is that you don't wanna have spaces. Okay? I'm just gonna let see isn't very clear. Commas cool. All right, so now this one. You guys were on your own. I want you guys to provide the following AIPAC name. You're just gonna, like, do this entire thing on your own and go into the next video when you're ready for the answer.
In short:
Always name your substituents in alphabetical order
Commas separate numbers from numbers, and dashes separate numbers from letters (i.e. 1,2-dimethyl)
10
example
Provide the IUPAC name for the following alkane
Video duration:
7m
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Video transcript
Alright, guys. So this one was actually surprisingly tricky right? From the very beginning, because the fact that there's a lot of different chains, that could be the longest chain. So I think one of the obvious chains that you might have thought of would be that this would be the longest chain. Okay, so that's possible. The only thing is that there's actually other combinations as well. That would also be Justus long. I could also make my chain go up like this. That would be another possibility. That would also be seven. And then this is gonna get ugly. I could also do this. Okay, All of these make seven carbon chains. All right, so we're gonna What I'm gonna have to do is go one by one and see which one gives me the most substitutes. Right? So let's go to the yellow one first. How many substitutes do I get? I get one up here to and three. Okay. Now, you guys might be wondering, Why did I assign that as two and three if they're coming off of the same carbon? Because they're two different branches. Okay, so each branch gets its own numbers. This would be three substitue INTs. Okay, three branches. So that's the number to beat. Let's see if any other chains can beat that. So let's do the one that I made in blue. That would have been like that. How many substitutes do I get for this one? What I get is one here. And then I actually just get one really complicated one here. Is that good? No, that's This was actually worse because this one just gives me to substitue INTs, and they both I mean, and it's it's less than three. So this one is not gonna be my answer. So let's finally do the one that I did in purple. So I'm doing this. How maney subsistence that do I get now? I'm actually gonna get let's see. 12 three, four. Yikes. Okay, so this is actually gonna be my longest chain, because this is the one that gives me the most branches. Okay, Now, this is probably the reason that you guys got this question wrong. If you got the question wrong, it's probably because you had the wrong change from the very beginning. Okay? Now what I want to do is go ahead and start using the other rules in terms of direction. Okay, so is this gonna be my one Carbon? Where is this gonna be? My one, Carbon. Okay, well, let's go ahead and start numbering. So my first substituted start on three. Fred, my first substitute would start on three for blue. So there is a tie. Okay, But then that tie is easily broken on the next round, because on the next round, my next substitute would be on four for Red. But my next substitute would still be on three for Blue. Why? Because I have to substitue. It's on the three position. Does that make sense? So I would start off in a I would have that one canceled with that one. But then I would have this one win and this one would lose. Okay, Because it's closer. So blue should be my number one. Does that make sense? Cool. So now I know that I'm numbering in this direction. That helps a lot. Now we just need toe get the substitute numbers and stuff. So this would be three. This would be four, and this would be five. Are you guys cool with that? So now we have to do is put all this together and get everything down on paper. So what's the root name? I like to separate stuff out. The route name is gonna be hep Dean. Okay. What air? The substitue int names. Okay, Well, in this case, I wanna put locations and substitutes. Okay, so how many different types of substitutes do I have? I know I have four sub situates, but in terms of types, how many do I have actually, on Lee? Two different types. I have metal groups, which I have three of I have three missiles. 123 and then I have 13 carbon chain, which is gonna become what we call a Pro Bowl group. Okay, so what that means is for substitute Wint's, I actually just have a try. Metal, See how that works? I put them all together instead of naming them out individually, Tri methyl saves a lot of space on, and then I'm also gonna have a Pro Bowl. Okay? Now all we have to do is have to get the number locations of all of these. Okay, so I'm gonna put sub out here to give me some more space. All right, So what are the number of locations of the tri metal? Well, for tri metal, I actually have to be explicit about every single location. Why is that? Because if I don't put exact exactly where each of the metals is, what I'm gonna wind up getting is a very confusing structure where I don't know where they go. So it looks like two of the methods are on the three position, and one of the methods is on the five. So the way this is gonna look is it's gonna be three comma, three comma, five dash, trying method, Alright, Tricky. Right? But that is the way that we name it. Because now I know that two are on the three and one is on the five. Now, I know that one of you got one of you guys is asking. But Johnny couldn't I just put 35 Wouldn't that be fine? Why not to put 335? No, you can't. Because then I wouldn't know. Where is the third one? Is it on the five? Or is it on the three? So you need to say that to our on the three and one is on the five. All right, then let's do the proposal. That one's easy. That one's on four. All right, so now I'm done with my roots. I'm done with my substitue INTs. Now all I with my route and substitue It's now all you do is put it together in the right name. So obviously there's gonna be a long name and have to figure out what's the correct order to say. All of these. You could have all of these steps, right? But if you put the name in the wrong order on your exam, you still got the question wrong. So we have to be very meticulous with each step. So now when we're ordering this, we have to go in alphabetical order and prefixes don't count. So that means what are we gonna talk about first? What's gonna be the first substitue int that we lead off on? It's gonna be try metal. And the reason is because off the m okay, M beats P. So that means that I'm gonna say that this is 335 I'm gonna run out of room, probably. So I'm gonna try to write a little smaller try metal. I'm gonna actually gonna take myself out of the page. Okay, 335 Tri metal. Then we've got four poeple because that one is the next one. Notice that every time that I have a number and a letter separated. Oops. Okay. Yeah. Every time that I have a number and a letter separated, I'm using a dash. Okay, so then the next thing would just be for poeple, And then I just got to say what the ending is. And the ending is helping without a space. So then it would just be help date. Isn't that interesting? Where the m beat the P in alphabetical order? All right, so if you got that answer, then awesome job. If you did it, that's okay, because I know that this is tricky. It's your first time. All right, So now let's go ahead and move on to the next topic.
Does this make sense? You just learned how to name simple alkanes. Give yourself a pat on the back!