Transcript for:
Organic Chemistry Course Overview

welcome to organic chemistry one this is kim 231 uh this is going to be a lecture series on this for the first semester of organic chemistry i will be doing it on youtube for you my name is dr smith course materials that you will need for this course we are going to be using uh wade's textbook on organic chemistry 9th edition in its solutions manual that is online i also recommend that you purchase a molecular model kit uh this will be highly useful when we are discussing structures of molecules and chirality i also again highly recommend that you purchase the acs organic chemistry study guide it is currently on its second edition there's a lot of first editions out there we recommend getting the second edition now you can purchase this on amazon and through other educational sites and just message me if you want those other sites course breakdown the homework is worth six percent of your grade uh participation is worth fifteen percent of your grade there will be a quiz four exams and then in between the exams there will be a second quiz this is going to be your alkene synthesis quiz this is the general schedule for this uh but it may vary depending on the semester and how it runs how do you succeed in organic chemistry uh organic chemistry is it can be extremely difficult for some people it should be a challenge it should stretch your mind and how you can and your problem-solving skills one thing that is a good indicator of success in organic chemistry is how much studying you do this is a general rule of thumb if you just use the lectures only so you can pay attention to these online lectures or in class lectures you and that's all you do you don't do any homework or additional you should expect that you are going to fail the course the course is a course that you have to practice doing problems so if you do the suggested homework problems these are the textbook problems these tend to be a bit easier these help you need them to develop a good foundation so you need the lecture and the homework sets to start creating your foundation most people don't pass the course just doing those two they end up having to do more difficult problems like reviews practice exam old practice exams and that will get you into the b range generally and then the students that do the best modify problems based off what they've seen in class and how we teach the course and they try to modify them to how we would ask on an exam keys to succeed first one is never miss class and take copious amount of notes um this is often forgot you know i can always reference what you said in class because there's lectures online that is not good studying habits you should always take notes um read ahead in the textbook you have multiple different avenues of getting the information you have the textbook you have the lecture series and you have online uh information that you can use so make sure you are reading ahead in the textbook and if you don't understand it use some of the online resources videos and these lectures this lecture series what i highly recommend doing is you write down the difficult subjects and you study those subjects more if you don't understand make sure you're using office hours to get a better understanding of it but again always write down the difficult subject that's what you want to study if you're studying the all the hard things hard subjects you will save a lot of time in your studying you need to do it consist study and practice problems consistently each day cramming does not work at all and this is a you need to learn this especially because many of you are planning on taking the mcat you can't cram for them cat and you can't cram for this course either so some subjects take multiple days to understand and grasp so if it takes three or four days to understand it for your brain to grab understand the concept then if you're trying to cram the night before you're not gonna get it and you will fail the exam or be on the low end where you're not happy with your grade make sure you're attending review sessions and redoing the review session packets or explore mores as we often call them practice old course material will give you old exams they're going to be found in live cloud make sure you use those kind of give you an idea of how difficult the exams are make sure you're studying with intelligent people people that will challenge you always find that good study group that's not always discussing what's the new thing on social media or in the news but there they can focus on studying for ocam or the course that you are taking always get enough sleep that is a very important thing uh college students tend not to get enough sleep i've seen many students fail my courses just because they didn't get enough sleep they understood the material but since they were so tired they bombed the exam and this one sounds kind of silly don't forget anything the reason it may sound something like how do i remember everything the reason i write it is because many of the new subjects that we are going to cover later on especially no chem 2 they are going to talk about things or subject material that was in ochem1 and it doesn't go away we're always building on previous material so since we're always building on previous material you do not want to forget it the most important is you must solve problems this class is based off problem solving um one analogy i give often is the basketball players you may watch basketball professional basketball players play and you may critique them during the game and go oh you should he should have went to the right he should went to the left but the truth is if you were in that situation you wouldn't have done better because you are not a professional basketball player you're not wonderful at that yet same thing applies here those professional basketball players practice forever to get good at it and that's the reason they're good at it same thing applies for ocam you need to practice to get good at it you can you may hear me say something and say oh i totally understand that the truth is you don't truly understand it until you can use it yourself and do it yourself so when you break it down organic chemistry when we're looking at the different types of learning there's the base that's the simplest form of learning and that's just knowledge that's memorization a lot of classes are based off that knowledge of just memorization it's not really truly understanding the concepts you just need to memorize your way through it which is not ideal then there's the next layers comprehension understanding and then we get to application problem solving we most of our exams start around the application and we will sit there and go through the last portion of this analysis where you have to understand new concepts based off the knowledge you have synthesis is putting ideas together making new ideas we tend not to sit in this range down below as much usually around three and four where you have to apply and do problem solving analyze new situations but sometimes we will do the synthesis where you have to put multiple ideas together in to answer a problem so do not expect to memorize your way through this course there is some memorization though uh taking notes is a very important aspect of succeeding in difficult courses and there is an art form to it it is not just a simple sit there and hey i write down when the professor says it's it's important i write down that's important that is part of it um but there it's a skill and people are good at taking notes always do better than if they weren't good at taking notes um most of the best students are wonderful at taking notes okay this is my suggestion on how to take notes you do not have to do it this way but if you look at the reasoning of why you should take notes this way and you make sure you're just following those reasons whatever method you use will turn out well you just need to understand the reasoning behind it i recommend that you print the notes and that you are actively taking notes so during these online lectures you're listening you should be taking notes if you're not taking notes you're not taking advantage of the lecture and it's fullest you're wasting a lot of time if you're not taking notes i recommend that you have three to four highlighters again this does not have to be highlighters it can be different color pens just a system that you follow when you take notes and this is the system and the reason i recommend highlighters so the very first thing you need to do is this is the most important is whenever you're taking notes or you're doing homework problems or you are doing review session or practice exams you mark it that with the ones i don't understand so i have it marked here in yellow so highlighting it hey i don't understand this material and this is the material that you must fix before the next lecture time or course class time you are this is the most important part of of your studies um because we build off previous materials so much if you don't understand the concept and we build off of it you are going to be lost so you must fix your mistakes when you're studying or the pro or the areas where you have a difficult understanding this and that one is left behind in a lot of when people train on how to take notes i don't know why but often like in junior high and high school they don't mention this but this is the most important thing when you're taking notes the second most important is what's going to most likely be on the exam the reason is what's going to be in the exam is because that's where the majority of your grade is coming from and if you're taking notes for a job or something what am i going to be using the most would be this highlighter i give multiple hints dr grubbs gets multiple hints dr sodom also gives multiple hints we give you ideas of what's going to be on the exam so when you hear those hints you should be totally excited and that you're marking your paper when you're taking notes like this will be on the exam because this will save you hours and hours of studying if you mark what you should be on the exam because we'll generally give at least half of the exam in hints uh don't come back and do it again so this is a different color or i've seen people write little clocks as their indicator of that need to come back and do it again so this is for when you're doing homework problems review brackets old exams uh the brain when you do a problem like that and you're having difficulty doing a problem and you okay i'm gonna go look at the solution in the solutions manual or in the solutions that we gave for the practice exam and you look at it oh that totally makes sense well you're not completely sure if you truly really understand the material um as i that basketball analogy well you saw the professional player do it so now it it makes sense why the professional player did it but can you do it so what i recommend doing is you write a date of when you did it or the date three days later and then you come back and do it three days later do that problem and the reason i recommend three days is the first day if you came and did it that night you're still going to have the answer kind of memorized so of course you can do it you have the answer memorized you're just going to give the memorized answer after the first and second day your brain starts to forget that memorized answer and around the third day that memorized answer is generally pretty much gone and now you have to re-figure out the problem and see if you can do it and this is that i am practic when you're studying it's i am practicing the stuff i have difficulty with and that's why we do it this will save you a lot of time studying and the fourth color this is kind of the bonus color this is the for the students that really want to succeed in a class or at work is stuff i need to modify and practice in in practice so you're trying to modify problems situations so that you can better understand the material and that you can better succeed in the course or in your job so that's the art of taking notes again you don't have to use highlighters you could use pens of different color if you have a tablet there office one note you can multiple different colors and it has different highlighters there's a or if you're using your ipad you can use different colors too and mark it up uh one other part of art taking notes in or actually i should say taking this class and doing a lot of the lecturing online you need to do a couple different things i am doing these lectures and they're mostly in the entirety of the chapter so they get very long you need to treat this lecture like a kind of like a textbook your textbooks are extremely long you don't freak out when you see a giant textbook you just read some and then you bookmark and then you read some more and then bookmark same thing with these lectures when you're taking notes you should write down your time so when you complete a section write down the time so you can come back and go get to it really quick because you're most likely aren't going to watch this entire lecture in one sitting because we have it's going to be a couple hours long and then you have all the practice problems in which you're going to add another hour or so so you you're not going to be sitting for three hours so make sure you're writing down the time in your notebook or on your tablet or whatever you're taking notes on so that you can easily come back to it another thing treat it like a standard lecture if you just watch these videos you're not going to do well okay you need to take notes and as i just mentioned you must take good notes do the practice problems when i say pause pause and do the problems yourself don't just rely on me because you don't have those skills yet and you're trying to develop it so make sure you're doing those problems next one is ask questions about the online lecture um i'm can't see your face because i'm this is a recorded lecture in a classroom i would be able to interpret what you're thinking kind of by your facial expressions and i would explain certain subjects more um if students were showing signs that they weren't understanding it so if you're not understanding something that i lectured or you think i made a mistake make sure you ask inform me of the mistake or like i'm pretty sure you goofed up the number here it should have been a nine instead of an eight um or i wrote something down i drew a structure and i forgot one of the atoms i often will do that when i'm writing really quick so if you have questions make sure you ask now like add one more to this do not have distractions that is one giant indicator if you're gonna fail or not i've watched students in class on their computer doing other things than what i was talking about in lecture immediately i know they're gonna have troubles in this course so that's gonna hold true for you too you're at home or at school or whatever watching these lectures if you have your phone going and your text messaging constantly or you have netflix or some sort of video going and you're also trying to watch the video new practice problems the distractions are going to make it extremely difficult to truly understand this material so please eliminate distractions alright so that gets us to organic chemistry well why organic chemistry why is this class so important well there's a couple different reasons um it teaches you techniques needed to study different difficult material i've had students that have taken mcat after this course and they bombed it the first time and then they wondering why they bombed it and they were going to go take it again and they and they started trying to fix their study habits and the funny thing is is after they fixed their study habits and i was talking with them they basically stated hey i started studying the way i study for oakhem the mcat and i did much better so this course will teach you great study habits um it increases your critical thinking skills better so you can better evaluate difficult situations uh again this is a very important indicator for medical schools and graduate schools they like to look at your organic chemistry even even if the subject you're going into doesn't deal with organic chemistry they like to look at it just because it tells them it's a good indicator of how well you will succeed in their program it's a great foundation for biochemical reactions you're going to go into biochemistry and biochemistry builds off of organic chemistry and you will see similar reactions situations in the bio and biological systems in this course if you're going on a graduate school you're going to go back and you are going to take biochemistry in graduate school if you're going to med school or pa school so it doesn't necessarily go away there is a very important information in organic chemistry that you can will be useful in the future and the last most important reason it's awesome it's okay okay so i'm gonna break down chapter one into its multiple different sections and we're going to go through those sections and discuss and give a good introduction to organic chemistry first section we're going to go over we're going to discuss the history review some of gen chem and discuss structures of organic compounds um we're going to discuss the different ways of drawing organic compounds and then also discuss elements of unsaturation and structural isomers of different compounds so what is organic chemistry well at first it was defined as vitalism is natural products that can only be produced in nature and they were needed to be that vital force some vital force that created them and so they thought only byproducts of humans or animals or plants could be are considered organic well with time we've discovered that it wasn't so frederick wohler in 1828 we have urea urea is found in urine and he discovered that if you take ammonium cyanate and you heat it up you will actually form urea and so that proved since ammonium cyanate's not coming from some animal source that is doesn't necessarily need to come from some organic comp uh organic material that's coming from an animal or plant it can it can actually be synthesized so we redefined it as the study of molecules that contain carbon and why is carbon so special and why would you make a whole subject on carbon well first thing is we got carbon here the sixth element on the periodic table and it can bond with pretty much anything on this periodic table it can bond to all the non-metals off to the right here and it can also bond to the metals the transition metals it can bond to the group one metals group two metals so alkali and alkaline earth metals it can bond with pretty much any element on the periodic table except noble gases it can also form single bonds it can form double bonds and it can form triple bonds so you get a large variation of different bond formations and it's tetravalent so it actually forms four bonds total but it can form four bonds and it can go all the way up to a triple bond so it can make form a very strong interaction between two atoms carbon can be a cation so it can have a positive charge that can react with anions carbon can be an anion also so it can have a negative charge whereas a lone pair it can form long chains so you can have a carbon bound to another carbon bound to another carbon and connection form these very long chains and they can get so long that they form [Music] they normally would be a gas if just small carbon chains and if you get really long they can actually be solids we use use them all the time they're plastics and polymers but again as i mentioned above they can form very strong and stable bonds again since they can form these strong and stable bonds they're necessary for life and co2 gas is converted into oxygen and photosynthesis and it breaks some of those strong bonds okay what do organic chemists do so we we study carbon but what can we do with that well there's different subject matters in organic chemistry one of them is the natural product chemist uh these people isolate and determine the structure of compounds found in nature this would be very important for drug new drug discovery a lot of drugs are found from compounds found in nature so we gotta isolate those and determine their structure making compounds so once we find these structures we have synthesis experts in organic chemistry they synthesize these compounds then there's those people that medicinal chemists they develop analogs of these natural products so you have somebody that finds them another person to synthesize them and a like a medicinal chemist they will form different analogs or slight variations of that compound where you're just changing a few elements to change how it reacts like the body or have different properties slightly different properties and then we have organic chemists that are experts in nomenclature um and then and last one you have the organic chemists that develop new reactions and study reactions and try to perfect reactions that gets us to our review of general chemistry so in chemistry we build on previous material and we are constantly building on previous materials so concepts don't go away topics that you definitely should know in organic chemistry that came from general chemistry you need to understand your periodic table you need to understand physical properties uh solubility density intermolecular forces like london dispersion forces hydrogen bonding you need to understand ionic charges molar mass be able to calculate molarity understand what isotopes are hybrid orbitals electromagnetic radiation chemical kinetics enthalpy entropy gibbs free for many of you gibbs free enthalpy and entropy will kind of scare you they don't go away we're going to do some calculations with them and then acid-base reactions from gen kim are also going to be coming back you might need to remember your bronsted lowry and your lewis acids which we'll add if you don't remember them from jenkins so the periodic table a periodic table i've seen it up in the right quickly the atomic number is the number of protons and also electrons if it's neutral so atomic number for carbon was six so it has six protons and if it's neutral it also has six electrons it has five electrons and have a positive charge they had seven electrons would have a negative charge the atomic mass is equal to the number of protons plus the neutrons so carbon 12 would have six protons six neutrons carbon 14 six protons eight neutrons most stable and these are going to be isotopes of each other because they have a different number of neutrons most stable inner and inert are the noble gases over here and we are trying to have the same most atoms are trying to get to that same electron configuration so that they are stable elements in the same group have similar properties so if you looked at this group right here group six we have oxygen sulfur they're in the same group so they're gonna have similar properties the halogens are right here they will also have similar properties to each other because they're in the same group and then chemical properties are determined by the valence electrons from the number of electrons in outer shell so if you don't remember valence electrons these electrons are the most important electrons they determine the bonding there the electrons are doing the bonding the internal electrons don't deal with bonding but the outer electrons do so if we looked at carbon it's electron configuration we have six protons in it because its um atomic number is six and they also have six electrons so if we filled the orbitals because electrons move in orbitals we put those there'll be two electrons in the 1s two electrons in the 2s and then we have two left over again we have to follow hund's rule paul exclusion principle and so forth and so this would be the electron configuration for carbon it has a 1s2 a 2s2 and a 2p2 and that's just stating there's two electrons in each of these orbitals because you can only have two electrons in each of the orbitals so what is carbon's electron electron configurations for its valence electrons so again valence electrons are the electrons in the outer shell outer shell is going to be the 2s so the twos so that is its valence electrons and you can rewrite it as helium which would be the internal electrons and then we have a 2s2 and a 2p2 so here's the valence as i mentioned previously atoms like to have their valence shell full so that it's two electrons or eight electrons in organic chemistry in the future you'll find out there's some rules that get broken for certain atoms but this is for this is for period one and period two they like to follow that rule they have two electrons in an outer shell or eight electrons once you get to period three and below you can break this rule but again they often will like to have the noble gas state if atoms lose organic electrons when they come in proximity of other atoms they're this is going to be called ionic bonding so you saw this like sodium and chloride in oak this is ionic bonding the electrons would go from the sodium to the chloride if you start with sodium neutral and chlorine neutral and they share electrons so then so these electrons are shared between the carbon and the hydrogen that is covalent bonding and this is again review from gencam and this type of bonding is dependent on the electronegativity of the atoms generally again this is generally if you have a metal and a non-metal so if you're looking at the periodic table not metals over here on the right these are metals so non-metals bonding with the metal this is generally going to be a ionic bond and that's because the electronegativity difference is not i mean is great between the nonmetals and metals but that's not always the case non-metal and nonmetal this is going to be a covalent bond there's just a small difference so if the electronegativity difference is generally below 0.5 it's nonpolar and if the electronegativity difference is between that 0.5 and this varies some people say 1.8 this is going to be polar bonds and then electronegativity is greater than that 1.8 it's going to be ionic and some books will state it as 1.9 instead so common bonding patterns so in organic chemistry we're going to be doing a lot with covalent bonds and there's going to be some common patterns that you're going to see and these will follow the periodic trends and you should initially memorize them you'll just practice them so much that you will memorize them so make sure you do practice that much if you're looking at some common patterns you have carbon it likes to make four bonds nitrogen likes to make three bonds oxygen two bonds fluorine one bond and hydrogen one bond this has zero lone pairs there's your lone pair likes to have one lone pair two lone pairs three lone pairs and zero lone pairs and this follows the periodic trend so periodic table if you have the halogens over here you had the fluorine chlorine and so forth they're going to fall in that same as the fluorine so fluorine chlorine bromine iodine they like to make one bond have three lone pairs and this is the common bonding it's not always happening but it's the most common there is a table of valence electro normal valencies so if you look at hydrogen there's three different types of hydrogen bonding or hydrogens that you can find hydrogen by itself when it's neutral it likes to make one covalent bond zero lone pairs charge is zero now if hydrogen has a positive charge it means it makes no bonds whatsoever it has no lone pairs and has plus one charge negative where it has a lone pair has a negative charge then you can go to like carbon carbon can make four bonds be neutral as a positive charge it only makes three bonds no lone pairs negative three bonds one lone pair this is a great little chart that you can use to get going at the beginning you can memorize to help you along but after a while just understand it so well and that gets us to drawing structures we have lewis structures condensed structures and line angle structures that we're going to deal with lewis structures is what you did in general chemistry these are messy they're time consuming and they have no 3d information in them and the reason i say they're messy is because if the compound starts to get 20 30 atoms long you have a lot of atoms and you're always it's hard to interpret the material uh determine the structure very well condensed structure formulas these are simple quick they don't give structural information directly and so they're sometimes easy to make a mistake from the formula and what structure the compound has and then we have line angle or also called zigzag we call it line angle consistently this one's the simplest and sorry i shouldn't say simplest it's simple it's quick and one problem with it though it's very easy to forget hydrogens because we do not draw hydrogens unless it's for certain functional groups so as a review i want you to go ahead take a moment we're going to do this consistently in lecture as i'm going to give you some practice problems i want you to pause the video and then come back after you've done it and then see what my answers are and you can compare and contrast um but we will do this consistently so plan on it and the best students will do it okay going to the first one we have methane here there's a carbon and four hydrogens carbon again is tetravalent so it likes to make four bonds and we have four hydrogens and so they're going to attach to that carbon the next one we have 4 carbons and 10 hydrogens and this 2 here is just telling you you can draw it multiple different ways in this case we could draw two different ways we have carbon sorry carbon is bound to another carbon bound to another carbon and it's bound to another carbon again carbon like to make four bonds so each carbon we have a hydrogen we're at five hydrogens right now five more to add to it and you can see at the ends we have additional hydrogen so there's generally two hydrogens per carbon on internal ones unless it branches and we have the additional hydrogens then so another variation of that is we can actually have a carbon with multiple carbons more than two attached to it so we have carbon carbon on each end and then maybe one more carbon so that's all four carbons carbon likes to make four bonds so i have to put hydrogens on the end of each of this the ones on the end have three hydrogens and this one in the middle already has three bonds and so we just need to add one more hydrogen and that will be our 10 hydrogens so these are two different structures you could draw with that molecular formula okay c2h5bro we have two carbons i'm gonna put the carbons together because it's organic chemistry generally it's carbon bound with carbons we have five hydrogens and an oxygen so if we put a bromine here put some hydrogens this oxygen can come off the carbon and then we put another hydrogen attached to it yes have two lone pairs the bromine likes to have three lone pairs and we can do multiple different variations of this that's why it's kind of blank right there so if you haven't done another variation go ahead and try to do another variation okay there's nothing that says this oxygen can't be in the middle so we can have oxygen carbon compares on the oxygen that the carbon is going to have a bromine another option for this one is two carbons instead of we could have the alkyl the oh and the bromine attach the same carbon so those are some another option for you and those are our three different ways that we could have drawn this and the last molecular formula we have three carbons four hydrogens and nitrogen and fluorine we have three carbons we have four hydrogen so let's just start putting hydrogens on the carbon fluorine hydrogen now we just have a nitrogen left so if we put this nitrogen attached here this shouldn't remember nitrogen likes to make three bonds carbon likes to make four so we're going to have to add additional bonds in a lone pair we can do this another way you could have made rings circles cyclic systems could add a triple bond in between the carbons fluorine and carbon here chlorine hydrogen nitrogen with like so again there's multiple variations of this you could have moved in the first one your fluorine could have moved over one with the switch with this hydrogen and the last one fluorine could have gone on the nitrogen right now you don't need to know all the rules on what bonds are acceptable or stable but you need to be able to draw all the variations of the lewis structures okay before we move on i am going to show one more concept that gets used all the time at least i use it all the time let's we're going to take this compound right here and we're going to modify it slightly so some instructors like to change the way they draw structures and i am one of those and where i use two electrons are represented as a line and that could be for a bond or for lone pair so instead of drawing the dots for lewis structures i draw lines dr grubbs does dots i think dr sodom does dots generally too so based on your instructor if you have to do it for homework or for an exam if it's a written exam follow the instructor's system um so for my class use lines for dr grubbs or sedom i believe it's dots and that gets us to condensed formulas condensed formulas is we try to simplify a molecule and get rid of the bonds drawing the bonds because you know drawing bonds can be time consuming and we just write the elements and the atoms are attached to in the quantity we use subscripts and a parenthesis as we go down the chain to describe what they're attached to so the rules for this electrons and single bonds are not shown so do not show lone pair of electrons and don't show bonds there are some limitations to that but generally their single bonds aren't shown bond atoms are written in their bonding order so up above you have the ch3 has attached this carbon over here and there's three of them attached to that carbon and we move to the right so as we move down we go down the bonding order multiple bonds though are shown for clarity so or but not always so sometimes we will write compound like this or we can also just write it like this either one is acceptable so sometimes we show the double bond sometimes we don't for condensed formula uh groups of bonds are groups bonded to the same atom are shown in parentheses so if you look up above we have this compound up above you have the c there's a ch3 and it says there are three of these ch3s attached to this carbon so here's your carbon actually i'm going to switch colors here and that's the green carbon and there's three ch3s attached to it and that parentheses that's what tells how many the quantity of the groups there's also repeating ch2s will be shown with the parentheses and a number and we have that example up above here in purple so we'd have ch2 and there are three of these ch2s challenge here and number six is handling oxygen oxygen there's multiple different ways on oxygen or different bonding on the oxygens you have the cho which is the one we have above that cho right here cho is this where you use carbon double bond to the oxygen and then a hydrogen attached and then you have the ch2och2 that would have been ch2 oxygen lone pair ch2 and it's bound to other elements and then the last one would be a ch 2 o h for rings you have to show the bonding for rings so if we had a compound that made a circle what we call ring make it cyclic it's three carbons it would look like this for the lewis structure and if you did it for condense it would be ch2 ch2 ch2 okay one concept you really need to understand from condensed formulas is you're following the general structure or general trend for bonding for the atoms so carbon likes to make four nitrogen likes to make three oxygen likes to make two okay so the cho right here you get a ch2 right before it and it's bound to cho and you're going oh it's there's a carbon and it's bound to a hydrogen and then there's oxygen well hydrogen only likes to make it likes to make two one bond you have two so you know immediately there's something wrong so maybe it's like this where the oxygen hydrogen well then carbon only has two bonds and carbon does not like to form two bonds because it's not following its octet when it's neutral so that's bad too the way you're going to remember this is you wants to fill its octet so one bond to the hydrogen two bonds to the oxygen now it will fill its octet and the carbon will be stable so make sure you're following those general principle general bonding patterns when you're doing condensed formulas and if you're breaking them you most likely goofed up in interpreting your condensed formula or making your condensed formula okay for the very first compound we have ethane it's a ch3ch3 you could write it like this we have two ch3s next compound is isobutane there's a couple different ways we can write this we have three ch3s and you can put this in parentheses ch so there's three ch3s attached to this ch sometimes you will see it like this it's not the preferred that means there's one ch3 coming down hexane here we have n-hexane you write ch3 for the terminal and then you have one two three four ch2s in a row and then another ch3 okay diethyl ether will often be written like so where is ch3ch2 and it's bound to an oxygen and there are two of those bound to that oxygen you will also see it written like this so do not be shocked to see both um this is the preferred the first one because it's the simplest meaning there's not as much writing involved most organic chemists are lazy and they want to make it the easiest way possible to write a compound so they don't have to spend so much time writing moving on we're going to discuss ethanol which has a ch3 there's a ch2 and then an oh the next compound there's two ch3s it can be written where you two ch3s those are the ones at the end and then we have a c-h-o-h and then the last one where dimethylamine you have your nitrogen there's two ch3s attached to an nh again sometimes these compounds will be written like so just do not be shocked when you see that so this one sometimes is written like this actually where the o h is in parentheses and they have a ch3 and the parentheses is just stating its attached to the carbon there's some more condensed formulas uh we have two butane we're looking at the double bond and two butane there's two different ways you could write this you have the ch3chch again as i said you have to follow the octet rule when you see that like well that carbon is attached to that carbon and it's attached to that hydrogen and it's attached to that carbon that's only three bonds that means there has to be a double bond in there in order for it to fill its octet again you can write the connect structural formula both ways the one on the left or you show the double bond uh we have acetonitrile the lewis structure you can write it as ch3cn or you can ch3c triple bond to the nitrogen you will see this one a lot more than the one on the right and then like acetylaldehyde there's that carbon double bonded oxygen and the hydrogen which i mentioned before which is our cho so you'll see the one on the left generally sometimes we will show the double bond and then we have acetone we have a ch3 co and then ch3 again looking at this carbon it's bound to this oxygen it's bound to this carbon and it's bound to this carbon that's three bonds so it has to have a double bond somewhere those other two carbons they have two ch3s and so it has to be a double bond to the oxygen and then our last one acetic acid where we have ch3 and then c with two oxygens and then hydrogen it can be written three different ways you have the ch3cooh you can write where you show the bonds and then often the most uh often way of writing it is ch3co2h and that's the one i'm going to use mostly okay so go ahead and do these practice problems and come back when you've completed them okay we are drawing the lewis structures of the following condensed structures so looking at the first compound there's ch3 and there's three of them well you can't have three ch3s attached to each other because then we're gonna be breaking the octet rule okay that middle carbon has five bonds which is 10 electrons so that cannot be it so that means these ch3s are attached to this carbon so we have that central carbon with their three ch3s and that carbon is attached to 3ch twos this is from the example above so if you remember it this should have been pretty easily and then that cho again carbon has to have four bonds right now it has one one with the hydrogen it needs two more so it's going to bound with the oxygen oxygen like to make two bonds and lone pairs like so okay next compound we have a ch2ch well again that's ch2 carbon only has two bonds with the carbon that's three so it's missing one so it's gonna have a double bond so now we're there there's a hydrogen attach carbon needs one more bond to the other carbon that carbon has a hydrogen and an o h draw correctly here and then that carbon is also attached to a ch and there's two of them so let's see h and then another ch well not enough bonds so it has to be a double bond here and then that's attached to a co2 h so carbon it's two oxygens attached one is going to be a double bond and then the hydrogen and so that would be the number two moving on to number three we have a ch3 bound to an oxygen oxygen likes to make two bonds going to bound to the next carbon carbon's bound to this carbon into this oxygen only so it has to have a triple bond okay so those two carbons are right here then we have a ch2 and then an nh2 nitrogen makes three bonds and has one lone pair all right that's converting those through three condensed formulas into lewis structures and that gets us to line angle structures or zigzag structures and this is the method that we generally will use in organic chemistry so you need to be familiar with it and be very comfortable with it it is much faster initially it feels like it's going to be painful but it will get easier the more you use it and then what do we do how does this work well we use bonds are indicated by lines okay carbon atoms are located at the intersection of lines and endpoints so i'm going to draw an example over here okay on the right we have lines these are the bonds and then there's a carbon at the intersection so right now the way i wrote it this you can see that there's three carbons and it's still up above three carbons hydrogens are not shown double bonds get two lines and triple bonds get three so i'm going to increase the length of this so come down here carbon double bond to another carbon and then we'll do one more change to it add one more carbon to this and then we're going to put an oh on it so we'd have our o-h so these two compounds are identical the one an example is the line angle formula so again there's carbons at each endpoint and intersection and we're following the rules carbon likes to make four bonds unless we explicitly show lone pairs and charge it's gonna make four bonds so that this carbon right here it's going to have three hydrogens attached to it this carbon here is going to have two hydrogens attached because our a has two bonds attached this one has two bonds already so it's going to have two hydrogens on it you can see those there the next carbon is going to have only one hydrogen attached because it has three bonds already it needs one more the next carbon is going to have one because it already has three bonds watch one more for the four and then the last carbon it's going to have two hydrogens because it already has two bonds okay again the rules are we don't draw the carbons um in general bonds are indicated by lines uh you have to be able to calculate the number of hydrogens double bonds and triple bonds get extra lines and then heteroatoms or anything that's not carbon generally would be shown so the oxygen nitrogen so forth okay well let's go ahead and do one or two of these and then you guys can try to do them on your own and then come back after you've completed them so the very first compound we'll do is hexane we have a ch3 there's four carbons ch2s which and then a ch3 so there's six carbons so two three four five six there's a carbon at each endpoint in each intersection so those are six carbons and that's hexane hex two in we have one two three four five six carbons again and then between the second and the third carbon there is a double bond and so that would be the line angle for hex twoing go ahead and attempt to do the next four on your own and then come back after you've completed them okay hexane threol we have again six carbons two three four five six and then we have an o h on that third carbon so one two three o h and you don't always have to draw the lone pairs you can do it if you need to if you react with those lone pairs then you will draw them in the future if you're not doing a reaction with them you generally won't draw them okay then we have cyclohexane two in one own you have the condensed formula drawing the lewis i mean the line angle double onto the oxygen and there's a double bond between those two carbons we have two methylcyclohexane one oh one all we have two hydroxy groups coming off these carbons like so and then the last one nicotinic acid uh niacin you have you need to draw the nitrogen down at the bottom there's double bonds and then we have now this you can draw a couple different ways you can write it as co2h like so you could draw draw it and that's generally how we're going to do it we're not going to write the carbon okay so those are the way of drawing the line angles from the condense as you can see it's much faster once you learn it and so in it's easier it's not as much writing okay we have a line angle structure here and i want you to determine the molecular formula so the number of carbons and number of hydrogens because on the exam you will definitely have a question that has a molecular formula and see if it matches a compound or you're going to have to determine the molecular formula formula from a compound so go ahead and try to determine it okay so let's go ahead and do this we generally will start with the number carbons i highly recommend that you mark on the exam whatever it is just count them so 1 2 3 4 5 6 7 8 9 10 11. so c 11 and then we want to do hydrogen's next so we have 2 3 4 5 6 7 8 9 10 11 12 13 14 15. do not forget the hydrogens that are on the heteroatoms the nitrogens are oxygens and i went through that relatively quick again you need to count the number of bonds so on the one on the far left there's two bonds already so that means there has to be two hydrogens this compound right here this atom right here has three bonds so it needs one more so we'll have one hydrogen now we get to the heteroatoms we have the oxygens there's two oxygens and then there's also a nitrogen and i wrote that wrong sorry generally we'll do an order on the periodic table so nitrogen and then our two oxygens and that would be the molecular formula for this compound okay moving on i want you to go ahead and write the line angle structures for the following condensed structures and come back once you've completed them okay the very first compound we have the three carbons coming off of one carbon then we have three carbons in a row one two three and then we have a ch two a c-h-o now on the c-h-o you are going to draw it out this is one of the few times you will actually write a hydrogen so make sure you write it out the next compound we have ch2 which is going to be a double bond with the carbon single bond to this the third carbon we have an o h coming off of that and then we have two ch2 two chs so that's going to be a double bond and then we have a co2 h which again if you draw it out look like this and the last compound we have ch3 bound to an oxygen bound to a carbon has a triple bond and then ch2 and then this goes to an nh2 okay those are our three line angle structures okay so we're going to do the molecular formula activity we're going to use this activity twice so once for the molecular formula and then we're going to do one that's for the elements of unsaturation elements of unsaturation which we'll talk about so i want you to go through these compounds and determine the molecular formula for each of these compounds and then come back once you've completed that okay so let's go ahead and do the first compound we have five carbons in a row two c five there's going to be three hydrogens the first carbon two on the next two on the next two three and so we're going to have h 12. on the next car uh compound we have one two three four five six seven eight nine ten eleven carbons doing hydrogens we have one two three four five six seven eight nine ten eleven and then we have a nitrogen on the next car compound we have one two three four five six seven carbons hydrogens we have two 3 4 5 6 7 8 9 10 11 12 13 14. the final compound on that first row there's four carbons there's going to be four hydrogens and two oxygens moving to the second row again one two three four five six carbons we have one two three four five eight hydrogens and then one oxygen next one we have one two three four five six seven eight nine ten eleven twelve thirteen fourteen doing hydrogens we have three three three so there's nine 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 we have a nitrogen and two oxygens next compound we have one two three four five six seven eight carbons we have one two three four five six seven hydrogens and then we have a nitrogen on the last compound we have 1 2 3 4 5 6 7 8 9 10 11 12. hydrogens we have you can use symmetry to help you along too so there's two three four five same on this side so 10 11 12 13 14 15 16 17 18. and then we have two oxygens and two bromines and that's those are the molecular formulas the elements of unsaturation we'll get to in a second all right so elements of unsaturation uh we're going to use this when we're determining structural isomers which are those same molecular formula but they're actually different structures one of the first things that we're going to do is we're going to determine the elements of say unsaturation or degrees of unsaturation and there's an equation for this is eu equals one half two times the number of carbons plus two minus the number of hydrogens that's the simple version of that equation and in the simple version if you're going to use that nitrogens they count as half of a carbon oxygens we don't care about them we don't get them at all halogens they count as hydrogens make one bond and since they make one bond just like hydrogens they count if we expand the formula the eu equals one-half two times the number of carbons plus the number of nitrogens plus two minus the number of hydrogens plus the halogens or minus halogens if you it was separated non-parenthesis and this is expanded formula so let's go ahead and try to understand this a little bit more so elements of unsaturation it means that there's not maximum number of hydrogens and the way we can get this it's like a ring so a ring we're going to lose some hydrogens in order to make the ring so if we had three carbons made in a ring we'd lose two hydrogens a double bond also counts as a unsaturation of one we've lost two hydrogens if we have an unsaturation of two we're gonna lose four hydrogens and that could be a triple bond or also could be two double bonds it could be a double bond and a ring it could be two rings so all these compounds have the same molecular formula they just have different bonding in order to get the unsaturation to two and that's if we were comparing it to four carbons we lost minus four hydrogens when we go to the following compounds now if we had unsaturation of three now it's going to get even more complicated we're going to have a triple bond or we could have a triple bond and a ring we could have a triple bond and a double bond we could have three double bonds and then one two three four five two double bonds in a row you could have three rings and i can't draw three rings with this compound let's let's lengthen it we have six carbons two three yeah plus one more carbon you can do two double bonds in a ring and we can do two rings and a double bond so that would be unsaturation of three as you can see if you go back unsaturation of one we have a ring or a double bond so one is very easy to determine the number of structural isomers once you start increasing it to two and three your options increase dramatically so elements of unsaturation again we can figure it out by the number of bonds and we can also determine it by our equation so right here we're going to determine it by our bonds so again single bonds don't count double bonds count as one triple bonds count as two rings count as one so going through this we have a ring so there's one we have another ring which is going to be one and then we have three double bonds which is going to be three and then there's no more double bonds or triple bonds or rings so you add those all together our elements of unsaturation is going to be five so what we're going to do is we're going to do the elements of unsaturation fraction practice and that is back at our molecular formula practice you're going to use the two different i would like you to use the both the methods to determine it use the equation and just looking at the molecule okay very first one there's no double bonds triple bonds rings so it's zero if you did the equation eu is equal to one half the number of carbons which is five plus two minus the number of hydrogens so two times five is ten plus two is twelve minus twelve it be zero so half of that would be zero okay the next compound if we're just counting it we got four from this ring and it's three double bonds and then one from this one and then there's a triple bond right here so that's two so overall this is going to be an eu of 7. if we did the equation eu is equal to one-half two times the number of carbons which there are 11 plus half the nitrogen so 2 times 11.5 or you could say 2 times 11 plus 1 plus 2 for the number and then minus the number of hydrogens we have 11 hydrogens and here's your equation so we have eleven and a half times two which is 23 plus two is 25 minus 11 um is 14 14 divided by two is seven so it matches and this is a great way of double checking to see if you got your problem uh you did it correctly in determining your molecular formula okay the third compound c7 has a double bond so it's one for double checking eu equals one-half two times number of carbons which is seven plus two minus fourteen and that equals one last compound on that first row we have c4h4o if you're counting there's one one one so three and then also eu is going to be one half two times number of carbons which is four plus two minus number of hydrogen which is four so that equals three moving on we have three from the ring so eu is going to be three the equation two times number carbon which is again our six plus two minus eight we have 12 14 minus eight is six divided by two is three so they match we have a double bond here two rings so our e is three e equals one half two times number of carbon which is our fourteen nitrogen which is one of those plus the two then minus number of hydrogens which is 25. so we have 28 31 minus 25 is 6 divided by 2 is 3. so they match so our multiple formula is most likely correct okay third compound on that fourth a second row eu we have four from the ring two from the double bond here i mean the triple bond so our eu should be six if we throw it into the equation one half two times number of carbons which is eight plus the nitrogen plus the two minus the number of hydrogens which is seven sixteen plus three is nineteen minus seven is twelve divided by two is six so we're good and then the last compound we have one two three rings so it's three double checking our answer eu equals one half two times number of carbons which is twelve there's no nitrogens so just plus 2 minus number of halogens which is 2 and the hydrogens which is 18. so we have 24 26 minus 18 is 8 minus 2 and 6 divided by 2 is 3. all right so that is our molecular formula practice and the elements of unsaturation and you're going to be using elements of unsaturation quite a bit so make sure you memorize that formula okay this would be a good exam question we have ethanol estradiol which is a birth control drug uh i want you to determine the number of carbons it has number of hydrogens and indicate the degrees or elements of unsaturation okay number of carbons again i highly recommend marking it so at 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20. double check make sure you didn't miss any okay now we're gonna do the hydrogens again i recommend marking those so we got one two three four those two don't have any 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24. and then elements of unsaturation do that in green we have four here one one one for all each ring and then for the triple bond we have two so adding those up we have five six seven eight nine now what i recommend doing is drawing out the molecular formula writing it out so you we can do the elements of unsaturation by the calculation to double check our answer so we have two oxygens okay eu is equal to one half two times number of carbons with 20 there's no nitrogens so plus 2 and minus number of hydrogens don't have to worry about oxygen so we have 40 plus 2 is 42 minus 24 which is 18 divided by 2 which is 9. so another reason this is such a good idea is to double check your answer if you get a half value for your product for your final answer you definitely know you counted wrong somewhere and that leads us into structural isomers so we've already done some structural isomers at the beginning when we were doing lewis structures i showed the little number in parentheses of two there's two different structures we can make these are structural isomers so if c3h6o you could have a compound like this but we could also move that carbonyl into the middle or that c double bond o these have the exact same molecular formula but they have different connectivity so they're called structural isomers or also known as constitutional isomers either name is appropriate so what i want you to go ahead and do is we're going to do some structural isomer practice go ahead and do these problems and then come back when you've completed them okay for this first compound we have c3h6 oh first thing that we do always find the eu one-half two times the number of carbons plus two minus number of hydrogens which is six so this is going to be eu of one so that means we have a double bond or a ring you can't have both of them just a double bond or a ring so we're going to draw the double bond we have where we have what's called a carbonyl so we have our double bond at the end and then we can move it down one if we moved it one more over [Music] these two compounds are identical we just have to rotate them so they are not structural isomers so this one will not count because it is the same compound as the first one okay then we can also do a carbon-carbon double bond so our three carbons oh we could also do it the oh is on the carbon-carbon double bond do it like this also if we move that double bond these two are identical we just rotated the compound so they don't count as structural isomers and then we can do a ring because again it has an eu of one so three carbons and then an oh we don't have to do an oh we can also do an oxygen in between the carbons so we have this four member ring here each of those would be acceptable this should be all the compounds for this c3h6o actually there's one more sorry there you go okay moving on to more structural isomers so go ahead and do these structural isomers the number in parentheses tells you how many possibles you have okay looking at the very first compound we have c3h8 streak eu on this compound is going to be zero so that is your only option c3h6 eu again one half two times number carbons plus two minus six equals one and so on this one we have a couple different options we have the double bond and then we also can make a ring and three member ring those are two options moving on c3h8o you three carbons plus the two oxygens don't matter minus eight equals zero so three carbons with no h we can move the o h into the middle you can't move it any further in the middle we can also put an oxygen in the middle between two carbons and these would be the three structural isomers moving the c3h7 in again eu is our first priority one-half two times number of carbons plus one from the nitrogen plus two minus seven hydrogens our eu is six nine seven one okay so we are gonna have a double bond or a ring so if we do our three carbons and then a nitrogen we just need a double bond in there we can move that double bond over move it over one more time we can do a branch actually let's take the center one and move it over once and then we can take that and have a double bond to the nitrogen okay and then we can do rings so triple bond and h2 we could do four member ring um we can take the nitrogen do branching off of it so as a double bond to the knight to a carbon has two groups coming off two carbons coming off you do it with one carbon coming off so there's nine of our 11. you could do double bond then the nitrogen and then the carbon and it's going to have hydrogen and then our last one is one more of the rings we have nitrogen is in the ring give the carbon coming off there's actually another one too so we have 4 5 6 7 8 9 10 11 12. we miscalculated okay c3h6o we have eu equals one half two times the number of carbons plus two minus six so that's one so we have a ring or double bond okay there's our first compound we can move the double bond over one can't move it over anymore we could have double bond with carbons and we put the oh on it various forms of that and then we could do an ether form which is double bond oxygen and then we can start doing rings we have three carbons and oh you could put the oxygen inside the ring you can also do a bigger ring and those are nine different of structural isomers for c3h6o okay the next compound eu is going to end up be going one so we're gonna have a double bond or a ring there's four carbons double bond you can move it down one we could do a branching also we can do a ring one carbon off or we can do a bigger ring and those are four five structural isomers next compound we have c4h6 two times that four plus two minus six equals two so that means we have triple bond two rings double bond in a ring or two double bonds these are all our options okay so doing the very first one we do triple bond four carbons we can move it into the middle if we move it again it's the exact same as the first we can do a little branching here too oh sorry i can't do any branching um then we can do two rings four carbons it's the only option for two rings double bond and a ring let's draw that be like that or it could be inside the ring it could also be inside the ring where the ch3 is attached to the double bond we can make the ring a little bit larger and then our next compound we have two double bonds so we did two double bonds like that or we could do two double bonds like so now it's gonna be our nine compounds okay moving on is c4h10 two times four plus two minus ten so our eu is zero so four carbons and we do one branch say c4 h11 in there's supposed to be eight of these eu equals one-half two times four plus one for the nitrogen plus two minus eleven and that is going to equal [Music] zero so there's no double bonds or triple bonds four carbons then our nitrogen we move that nh2 down the chain remove it again it's the exact same that's the very that's the second one we can do branching off the nitrogen or we can do branching off the carbons so four carbons and h2 and then we have nh2 okay now i did what this is a common theme with four carbons you have the linear you could do this with alcohols halogens whatever it is you have the linear version i'm going to write it as x you have what's called an iso version of it which we'll find out and then a sec version of it and then a t which i goofed that one of these up the t okay now that's just the common theme with four when you have an eu is zero so look for those four different all right now we can branch off the nitrogen that would be one acceptable three carbons off the nitrogen we could have two carbons off the nitrogen and we could also have a branching and that's our eight options right there c4h10o two times four plus two minus ten so one half two times four plus two minus ten and that is going to be zero as i stated with the previous one four carbons you have the linear and then o h you're gonna have the branch o h move that branch down one more o h and then you have the t oh h and then we're gonna also have where the oxygen is in between carbons this one could be branched also and those are the seven for the o-h and oxygen in between okay the last with c6h14 can always do the eu and so it's zero six carbons take one methyl group and just move it down one let me take one ch3 and move it down one move it down again you move it one more time it's not gonna it's gonna be identical to the previous so we're gonna do a second one carbon so two carbons coming off and then we can also take third get it branched again those are five okay those are structural isomers again you you should practice these get pretty quick at them um on the exam or quiz often we'll just give you a molecular formula and say how many structural isomers so you need to be comfortable finding them all and that is done by just practice that finishes our first section of the slice for chapter one go find that i recommend finding the second video for chapter one and continue on going through chapter one