 Hello? Okay, good morning everyone. Sorry about that. So I think we finished up here last time. So let's, somewhere around here. So let's just start here. Again, remember alkenes are compounds that contain at least one double bond. Here's some examples of some alkenes. Hopefully everybody can see the alkenes, right? The double bond. So you guys see the double bonds in these compounds? So if I were to give you one of these compounds, you were to need to say this is an alkene point for the double bond or whatever. Okay, so let's talk about geometric isomerization or geometric isomerism and alkenes. I think we started this maybe last time. We can do it fairly quickly today again. So geometric isomerization is when different compounds have the same molecular formula and connectivity. This term connectivity, remember, refers to the way the atoms are connected within the structure. So let's look at these two molecules, compare them to each other. So if we start our counting, if we wanted to count carbons, for example, we started our counting at the left hand side here. We would notice we'd have the methyl group, which would be one, then the double bond carbon, which would be two, the other double bond carbon, which would be three, and the last methyl group, which would be four. Okay, so does everybody see that I just counted the carbons in the carbon chain there? So notice if we did that same thing, one, two, three, four, over here, all of the atoms would be in the same positions, except they're arranged spatially different. By the same positions, I say, well, if I follow the bond lines, I can go from one to two, then from two to three, three to four. I can do that one to two, two to three, three to four. But of course, we see that the carbon or the methyl group at position one has switched in a spatial arrangement with the hydrogen atom here at the same place in the double bond. So does everybody see what I'm talking about there? Okay, so what we say is the connectivity of these two molecules is the same. They're connected the same way. Does that make sense? Hopefully that makes sense. They're connected to the same atoms. They're connected to the same atoms. They're just arranged spatially differently. And if we look at an alkene, so put together this molecule, or at least the one on the right there. Okay, so hopefully everybody can see that that's that molecule, that I've drawn on the board, okay? Notice that when I try to turn around the single bond, it's able to turn quite freely. Do you guys see that? Okay, that's able to turn fairly nicely. But when I try to do that around the double bond, what do you think happens? The not easy at all. In fact, it doesn't do it, okay? Why is that? It's because there's these two bonds holding this thing together, okay? Of course, if I were to break one of those bonds, specifically the pi bond, I could rotate it and make the other geometrical isomer. Do you guys see that? So that's what's happening to these two compounds. The reason why they're not the same compound is because they have that double bond in them, okay? So it causes around single bonds, we have this phenomena that you just witnessed, right? Well, we call free rotation. You can rotate around a single bond as much as you want. And in fact, the molecules do. So you can rotate around like that and you have the same molecule, no matter where you're rotating. That's just like me going with my hand, right? Like that, of course I'm the same person if I do this or if I do this, okay? Around a double bond, there is no free rotation. You can't do that. So that means that when the compound is in this form, it's going to be totally different compound than the compound that's here, okay? Even though they have the same molecular formula and the atoms are connected in the same ways, okay? So we call this phenomena geometric isomerization or these are geometric or isomers of each other, okay? When they're on the same side, we call that cis or z, okay? So you can remember it because of this like common thing that people say, z is the same side, okay? So you'll remember z is the same side, right? So since the things are on the same side, it's z. Okay, the other one is called trans or e, okay? So I want you to know all these names for these things. So when I've got the two big groups of the double bond on opposite sides like that, it's called trans. If I got the two big groups on the same side, it's called cis, okay? Does that make sense? So we're going to look at a survey of a few, see how it works. Oh yeah, that's awesome. It's my new eraser, okay? So there you go. There it is written out. The cis isomers have the two big groups on the same side of the double bond. The trans have the two big groups on the opposite side. So notice that when we look at the physical properties of these two molecules, I know it's probably hard to see from back there, but if you look at this table, you can see that you actually have different physical properties. So the melting point is quite significantly different of these two molecules by about 35 degrees Celsius. The boiling point is different about three degrees Celsius and the density is different. So this hopefully proves to you that these are two different compounds, okay? And they can't be changed into each other without a chemical reaction. So here's some more geometric isomers. What I'd like you to do is help me out and figure if we can call these easy trans or cis, okay? So what about this one? Is that going to be cis or trans? Cis, why is that? Because the two big groups are on the same side, right? What about E or Z? What will we call that? Z, okay? So we all cool with that? So notice this compound is a geometric isomer of this compound, do you see that? Okay, so you're going to have to, when I give you those things, you're going to have to recognize that value, okay? Or if I could say draw the two geometric isomers of this compound, okay? Notice here, those are geometric isomers of each other. Do you guys see that? Okay, so which one is this? Or how about this? Which one's the E geometric isomer? The one on the right. What about the trans geometric isomer? The one on the right, okay? So of course the Z or cis would be the one on the left. And what about this compound? Can you tell which one's the bigger group? Where's the double bond? So the double bond is right there, right? That's a cis, right? Cis, okay? And it's geometric isomer is right there. Okay, so these are fairly simple alkenes, right? You can imagine that these molecules can get much bigger. Let's see if I have a, see look at this alkene, how big that alkene is, right? It's got one, two, three alkenes in it. We call that a triene when it's got more than one alkene in it. Look at this one, it's got, you know it's pretty big molecule of alkene in it. This has two alkenes in it, do you see? So what about this one? When we talk about the double bonds, right? We've got two double bonds here. So we're gonna have to say one of those double bonds is this and the other one is this, right? So if I asked you, this double bond here, is that gonna be a cis or trans double bond? Cis, what about this one here? How would we figure that out? How would we figure that out? But what about this one here, right? So this is groups two for this double bond. So let's look over here, right? So there's that compound. Let's figure out how we would mention or how would we designate these as cis or trans. What about this one here? Is this cis or trans? Why do you say that? What's the rule? What's the rule? What is the rule? What do we say was the rule? The two big groups, right? What are we talking about? Big groups are, so you're referring to the bromine and the hydrogen being the big groups or the two chlorines being the big, so how did you decide that the chlorine was bigger than, no, bigger doesn't mean more, right? That's not the same thing, right? Like, how would we decide what's bigger? So you just decided, oh, it must be the chlorines because they're the same thing, right? That's what you've noticed, okay? That's not the way you do it. I said the bigger groups, and so that's the way you do it. Don't make up your own rules, okay? So if we look, how do we decide what's bigger? Well, we've got this huge table here that we've been looking at for the entire semester telling us which atoms are bigger than which other atoms. So you're gonna have to reference the periodic table. So if we look here, are we gonna ask ourselves, well, which one's bigger, chlorine or hydrogen? Well, we look, hydrogen's atomic mass is one, right? Chlorine's atomic mass is 35, so clearly chlorine is much bigger than hydrogen, okay? So we're cool there, so we'll say that. Now we gotta compare the other side, right? Bromine and chlorine, which one's bigger, right? It's not chlorine, right? Because when we look at the periodic table, we can see that chlorine has an atomic mass of 35.45 or an average atomic mass of 35.45 and bromine has an average atomic mass of about 80, right? So clearly, bromine is bigger, okay? So it's not just saying like the two same things are on opposite sides, you gotta look for the bigger of the two around the double bond. So in this case, it's not a trans double bond, right? It's a cis double bond because the bromine is bigger than the chlorine, okay? So it's kind of a trick, right? So you gotta watch out. So now we're going to do these cyclic structures, okay? These are much more difficult to figure out or not much more difficult, but a little bit more difficult. And I'm going to show you how to do it. Right now. So, let's do that bottom one. Well, let's look at this first. Okay, so notice this has two alkenes in it. It's got one there and one there. Do you guys see that? The two alkenes? So if I were to ask you, let's look at this bottom alkene first. Is that a cis or trans alkene? Can you see it? Here, I'll draw it up on the board. So the bottom part, well, the whole thing is like this. So that's what it looks like. So we're looking at this double bond here. So what do you gotta do first to decide if it's cis or trans? So what did we do on this one up here? We looked at one side of the thing and then we looked at the other side of the thing, right? Okay, so let's do that. What is on this side of the double bond? So how many of them? Two, right? How do you know that there's only two hydrogens on that side of the double bond? Hydrogen can only make one bond, but more specifically, what can carbon do? Carbon can only make four bonds, okay? So since this carbon already has how many bonds on it? Two bonds, it needs to make two more bonds, right? And remember, if those two bonds aren't shown, it's implied that it's hydrogen that's making those bonds, okay? So what's bigger, hydrogen or hydrogen? What's bigger? Which one is bigger, hydrogen or hydrogen? Neither one of them is bigger, right? Okay, so if neither one of them is bigger, can we call this cis or trans? Can we call it cis or trans? No, right? Why? Because we have to have things that are different, okay? So if they're not different, then it's not cis or trans, okay? In fact, does anybody remember what we call this type of an alkene? Something that you should remember from the notes previously. A terminal alkene, yeah, this is a terminal alkene, okay? So you guys gotta recognize that stuff, okay? So is this a terminal alkene up here? Is it a terminal? What does it mean terminal? But just not in alkene speak, what does it mean at the terminal position of anything? It's the end, right? Does the terminal mean it's in the middle of something? No, okay? So is this double bond in the middle of something? Yeah, so it's not a terminal double bond, right? So remember, the terminus is always the end, okay? So when we're looking at our carbon chain, no matter where we start, bam, we get to the end here, right? So that's the terminus, okay? So we say that's a terminal double bond. In fact, what kind of double bond is this double bond here? What is it, well, what is the internal double bond, right? Because it's inside of the carbon chain, okay? So you guys gotta remember that nomenclature. Now we gotta ask ourselves, okay, is this an E or Z double bond? Let's try that, or a cis or trans, okay? So on this side, it should be much easier to figure out what's bigger than on this side, I'll grant you, okay? So we've gotta go, well, what's missing on this side? What are we not showing here? The hydrogen, okay? So let's write that in just so we can figure out our double bond, okay? So what's bigger, what's here, what's this thing here? That's a carbon, okay? So the way we need to do this is just like we did it here, except there's no other atoms connecting to these ones, okay? So we gotta watch out what we do. So when we come from here, we gotta say which is bigger? Hydrogen or carbon, okay? Not hydrogen and all of this other stuff, okay? So it's not all of this stuff, it's just that atom there, okay? That's all we're asking ourselves. Which one's bigger, hydrogen or carbon? So which one is bigger, hydrogen or carbon? Carbon's bigger, okay? Okay, so we're cool there. Now we come over to the other side of the double bond. What's this atom here? Carbon, yeah, carbon, thank you, right? Because what did we say when you have, how many times did we say that last time? If there's nothing there, it's carbon or it's a methyl group specifically. Again, I can't remember how many times we said that last time, okay? So let's try this one more time. If it's at the end of a line, what's there? Carbon, thank you, tell me one more time. End of a line, what's here? Carbon, okay, we're all cool with that now, right? It's not hydrogen, let's just say it one more time. It's at the end of a line, it's not hydrogen, okay? So I think I said it just as many times as I said it last time. So hopefully you guys remember, okay? So what's bigger then, carbon or what's there? Carbon, right, that's an oxygen, right? If that were an oxygen, I would put an O there, right? Okay, so let's try this one more time, okay? What's that thing? Carbon, what's that thing? Carbon, so what's bigger, carbon or carbon? They're the same, okay? So what do we have to do now? Okay, well we have to go to the very next atom, okay? So what's the next atom up here? Everybody? The next one from the carbon. So if I were to make a bond to this atom, it would be to what? Hydrogen, right? How many hydrogens are there? Three hydrogens, right? Okay, so I'm not gonna put the other two, okay? They're implied, okay? So let's ask ourselves now. So that's hydrogen, hydrogen and hydrogen. Hydrogen's the biggest out of the, or they're all the same, right? They're all the same. So we can pick whichever hydrogen. So you wanna pick the biggest of those next atoms, okay? Now we ask ourselves, well what is this carbon bonded to? Okay, so what is it bonded to? Oxygen, how many, so how many bonds, okay does this carbon have? Four, right? It's got one to the carbon we're interested in and then three more, okay? What are those three bonds bonding to? Let's ask that question. Carbon, oxygen and oxygen again, okay? So I want you to think of the double bond as doing it twice, okay? What's bigger, carbon or oxygen? Oxygen's bigger, okay? So now what are we doing really? We're comparing what's bigger, oxygen or hydrogen, okay? Oxygen is bigger than hydrogen. So that means that this is higher in priority than this is, okay? So we got that now, right? So what double bond is this, cis or trans? Cis, double bond, okay? So it's just stepwise, you just see the next atom, next atom, next atom, okay? So don't think it's more difficult than that. The only problem is you gotta remember what these structures are representing. Just like if I were to write words up here in English, right, and you didn't understand what the letters meant, you couldn't understand what the words meant, okay? So we gotta remember all of our rules that we're putting together these molecules, these structures about, okay? So I'll let you guys try this one on your own. Tell me what is that double bond, cis or trans, okay? So try that one on your own, see if you can figure that. Okay, let's jump to the next type of functional group. Very similar to alkenes, it's called alkynes. So an alkyne is a compound containing at least one triple bond, okay? So remember that if we have a pi bond in our compound, which a triple bond has how many pi bonds in it? Two pi bonds, right? So an alkyne, it has, does it have a pi bond in it then? An alkyne has a triple bond in it? Yeah, it must have a pi bond, right? So if we say, if it has a pi bond, it's unsaturated, therefore all alkynes are unsaturated, okay? Acetylene here, that's the simplest alkyne. Notice the bond length, you can go back through the notes and look at the bond length of the alkyne, alkyne, and we'll talk about alkynes in a second. And you'll notice that single bond is longer than a double bond, which is longer than a triple bond. It's another good thing to know. Okay, so remember the general structure that we did for an alkyne, or an alkyne like I said, is very similar for an alkyne, except for because the carbon's making a carbon-carbon triple bond, it can only make one more bond, right? So we've got similar terms with the alkyne nomenclature as we did with the alkyne nomenclature, okay? So if we got an alkyne at the end of a chain, it's called a terminal alkyne, just like the alkyne at the end of the chain was known as the terminal alkyne, okay? If we've got an alkyne that's in the middle of the carbon chain, we call it an internal alkyne, okay? Does this make sense? So the hydrogen stops the carbon chain, right? Because can we stick another carbon to that carbon there? Not on, right? We can't do that. Why can't we do that? Because carbon can only make four bonds, okay? That's it, again, if anybody puts more than four bonds to carbon on any one of their structures, it will be automatically wrong, okay? The thing is, I am an organic chemist and the first rule you learn when you get into organic chemistry is carbon can only have four bonds, okay? It's like what's known as the cardinal rule of organic chemistry, if you will, okay? So if you break that rule, you are doing an injustice to everybody who has ever thought about organic chemistry, okay? So make sure you don't do this, okay? Carbon only has four bonds. That's all it can make. Okay, so are we cool with these terms? Terminal, internal. So, here's some alkynes. Let's try to figure out whether these are terminal or internal alkynes. What about this one here? Is that terminal or internal? Internal, right? How do you figure that out? Yeah, because it's, well, it's in the middle of the carbon chain. That's what you wanna think of it like, okay? What about this one? Is that terminal or internal? Terminal, right? How'd you figure that out? Yeah, there's a hydrogen there, right? It's at the end of the carbon chain, okay? If you haven't figured out, when we have these ch-ch-ch-ch-ch-ch of carbons, we call that a carbon chain, okay? So what about this one here? Terminal or internal? Terminal, right? How do we figure that out? Because it's CH there. So notice, you can draw your structures quite differently, right? I can draw my H sticking to my C like that, or I can draw it like that with a bond to it, okay? Or I could draw it like that, right? Is that a terminal or internal? Terminal, how'd you figure that out? Because what's bonded to this carbon here? Hydrogen, what about this one? Terminal or internal? Terminal, so notice here, this is the way you can draw a terminal, this is the way you can draw a terminal, this is the way you can draw a terminal. They all mean the same thing, okay? They're not all the same structure, right? Except for that alkene portion. What about these three? What about this one? Is that a terminal or internal? Internal, right? What's this here? Is that a hydrogen? That's a carbon, right? Make sure that's a carbon, okay? So notice, you can draw it like that, okay? That's an internal one. Clearly, hopefully everybody would say that's an internal one. What about that one? Internal as well, right? And then this one? Internal, right? I know, it's pretty bad, right? Let's go to the next slide. Okay, that's all you need to know about alkynes, okay? Now let's talk about alkanes, okay? So since we talked about more complex structures, now we're going back to the most simple structure so you can think about what's going on here. So an alkane or another more classical term for this is a paraffin, okay? So if you ever heard of paraffin oil, it's an oil of alkanes. So alkanes are hydrocarbons. What are hydrocarbons again? Molecules, right? They're containing what? Only, only carbon and hydrogen, okay? So go back in your notes, look where we've talked about this. We talked about it a few times. Alkanes specifically are hydrocarbons that contain only sigma bonds. What are sigma bonds again? Single bonds, okay? So if you're not one of the ones that's shouting these answers out to me, you guys need to start studying this stuff, okay? Because it's going to come back and bite you and on the final, okay? So alkanes can be represented by this general formula of CnH2n plus two. So this is about the extent of the math that you're going to get in this. So if I said I have an alkane, an alkane, so CnH2n plus two, if I said I got an alkane that has four carbons, you should be able to tell me how many hydrogens it has, okay? So if I had four carbons, it would be C4H, what? Good job, 10, okay? How did I figure that out? Because I just put n, because n, right? Equals four, put n there, n there, right? Got that? Okay, so if I said I have an alkane that has 10 carbons, what would be, how many hydrogens would that have? 22, okay, good. So methane here, that's the simplest alkane as you could imagine. This is natural gas, CH4. Notice the bond length relative to the bond length of the triple and double bonds, you should look at it. Here's the general structural formula of an alkane. So it looks very strange compared to the alkene and the alkyne, but remember, R's are just carbon chains, okay? So it's just something that would be like that, right? And it's just saying instead of a functional group there, we have just a little H, right? In fact, we've got three H's there, right? Remember that. So we can have a couple of different types of alkenes, or alkenes, we can have a normal alkane, or we could have a branched alkane. So remember, notice, these are structural isomers of each other, right? Why are they structural isomers? Because they have the same what? What do these things have the same of? They have the same molecular formula, right? So their molecular formula is the same, but what are they different in? The way they're connected, okay? So I want you to say they're different in connectivity, that's the way you want to think about that, okay? So notice the molecular formulas of these things are the same, but they're different in connectivity, so we call those structural isomers, okay? Remember, geometric isomers also have the same molecular formula, but they have the same connectivity too. They own the only thing is they can't rotate around that double bond, okay? We'll talk about some more type geometric isomers when we talk about cycloalkanes. Okay, so let's look at these compounds here and decide what's a normal alkane and what's a branched alkane. So when I point to it, you tell me if it's normal or branched. What about this one? Normal, right? What, how come that's normal, right? And when we look at it this way, that's normal, right? Why is that? Well, when we look, the carbon chain doesn't split, right? We don't have a carbon chain going off here and a carbon chain going off here. We see the carbon chain splits here, right? Just because it's drawn kind of weird, you know, drawn not in a line doesn't mean that it's branched, okay? So we just got to say carbon chain, look at the carbon chain. So is this one branched or normal? Normal, is this one branched or normal? Branched, this one? Normal and this one? Branched, so are we cool with that then? And do you guys see the relation between the bond line structure and the drawn out structure here, the condensed molecular or the condensed structural formula here? Do you guys see the similarities, okay? So make sure you can translate from one to the other, okay? So here's some more alkanes, okay? So they can get quite complex. You can see this one has, you know, three rings in it. One, two, three, there. So there's the ones that have rings, we call cycloalkanes, okay? So is this normal or branched, alkanes, normal? Is this normal or branched? Branched, don't get freaked out by these. Remember what these mean, right? What does this line mean here? It's coming towards us, right? And this one means what? It's going away. So this is showing perspective, okay? So this is showing perspective on a structural formula. Is this normal or branched? Branched. And these, we don't say normal or branched, we say these are cyclic alkanes or cycloalkanes, okay? So what's that atom there? Carbon. How many hydrogens does that carbon have coming off of it? Two, right? And why'd you figure that out? Because carbon can make how many bonds? Four, right? Four bonds, right? Okay, so what about that? What is that atom there? Carbon. How many hydrogens are coming off of that carbon? One. One. How'd you figure that out? Because it's got three bonds. What about this atom there? Carbon. And how many hydrogens? Two. Okay, very good. So what type of compounds are these all? Alkanes, but there's a bigger group of compounds. These are collectively known. Alkanes, alkynes, and alkenes are all part of what type of compound? So compounds that contain only carbon and hydrogen are called what? Hydrocarbons, okay? So you're gonna have to remember all of these things. Okay, and there you can see that alkane's getting bigger, bigger, bigger by one carbon each time. Okay, so you're gonna wanna know the name of the first 10 alkanes, okay? But they're really easy to remember, okay? So the first four are called methyl, ethyl, propyl, and butyl, okay? Those are hard to remember, except I'm gonna give you what do you say, a mnemonic device that helps you remember those, the mnemonic device is mice eat peanut butter, okay? So mice eat peanut butter. This'll help you catch mice too. Mice eat peanut butter. Okay, so methyl, you already know that. Carbon, one carbon is called a methyl group. The next one is ethyl. This is like ethyl alcohol, the stuff that you drink, okay? Propyl, this is like propane, okay? The stuff you cook your grill with. And this one is butyl. That's like what's in the lighter, butane, okay? So this is the, like if you've got a group coming off of here, we call this a methyl group. If we got two carbons, we call it an ethyl group. But CH4 is called methane, C2, whoops. This is called ethane. I keep wanting to do one more. That's propane, and that's butane, okay? The last ones are easy to remember because they're the Latin names of numbers. Pentane, hexane, heptane, octane, non-ane and decking, okay? So those first four are kind of hard to remember. Methyl, ethyl, propyl, butyl, but you'll remember them now because you know mysy, peanut butter, okay? Yep, okay? And here's the rest of them. You can see pentane, hexane, heptane, octane, non-ane and decking. And here's, if we look, methane, if we've got a CH3 group, we call it a methyl group, okay? Notice the number of carbon atoms increases, the boiling point increases, okay? So remember, boiling point and molecular weight kind of mirror each other. The bigger my molecular weight is, the higher my boiling point is, okay? This is like taking a tennis ball which is very small in weight and taking a bowling ball which is very heavy in weight and asking yourself which one do you think you could throw higher, okay? Because the bowling ball is much heavier, just like a big alkane is much heavier than a small alkane, it can be thrown higher up in the air, okay? So it's got more energy, okay? So the tennis ball can be thrown higher than the bowling ball, right? So that's like this dichotomy between small and large alkanes, okay? We'll talk about conformational isomers next time. Oh, really? That's where you are. Okay, I'll put the rest of the slides up.