introduction to organic chemistry for this session we're going to have three objectives the first one describe the atomic structure of carbon explain how the structure of carbon atom affects the type of bond it forms and third recognize how carbon atom forms different kinds of compounds with other elements in itself okay take a look at these pictures what can you say about it how does it feel when you taste or you smell these kinds of food they may smell sour like sweet and also the chili would be very very spicy yes so as you have known all these sensor experiences that we got from these kinds of food are caused by special compounds and these special compounds are very abundant in our environment not just in our food not just in our clothes not just in our in the things that we see around but also in our very bodies okay what comes into your mind when you hear the word organic ever heard of the word organic like organic food organic matter organic compound okay how about in these pictures which of these are organic and which of these are not organic okay if you got the answers right the organic substances are sugar this duck the cow the corn the banana the rose the berry the house material the plant except for the stone we will see why okay when we talk about the word organic it can mean different things to delay people the word organic would mean organic fertilizers or organic in the original sense from living organisms organic food those foods that are grown without synthetic fertilizers or pesticides all these kinds of food look at that organic but to the chemist these words matter differently organic defects compounds that contain carbon and other elements such as hydrogen oxygen nitrogen phosphorus and sulfur this it's talking about this composition for example this kind of compound all right in this subject we are focusing on a branch of chemistry which is organic chemistry this is the study of compounds that contain carbon technically compounds that contain carbon it is one of the major branches of chemistry a field of study that greatly contributes to the production of the consumer products we buy and use every day look at these kinds of figures these are some examples of organic compounds we can have this kinds of skeletal figures this one or we can have ball and stick so these are types of models that the chemists have agreed to show organic compounds molecular structure another terminology in chemistry is this difference between organic and inorganic compounds when we say organic it is having that bonds which are entirely covalent and inorganic the bonds are ionic ever remember about these two words ionic and covalent all right when we say covalent covalent bonding there is a sharing of electrons this usually happens among non-metals because they tend to gain electrons when we say ionic this happens mostly on metallic substances which usually lose electrons and as they lose electrons there is a transfer instead it's not sharing but transfer for organic look at this image this moving image the yellow small ones are the electrons the red one it's the oxygen atom and the white one it's the hydrogen would you look at that small yellow dots here come around oxygen and it's like they're sharing the electron from hydrogen so it is a sharing relationship for the second one look sodium has one one electron and this tiny electron is shared into the of chlorine and they become they still become bonded together but this time there's a transfer of electrons that is a type of an inorganic compound so sodium chloride is an inorganic compound whereas water not really organic well those are examples of the type of sharing in ionic and covalent bonds when we say organic they have covalent bonds inorganic ionic bonding these words bonding are types of chemical bonding that happen among atoms okay let's proceed but the there will always be exceptions to the rule not all compounds that contain carbon will be considered as organic some are considered as inorganic and these are the exceptions number one oxides number two ionic compounds of carbon based ions for oxide the first one is carbon monoxide number two it's the carbon dioxide just a little things to remember number two number two the carbonates cyanides carbide ions such as silicon carbide okay special things okay people before thought that organic compounds or compounds that contain carbon are just exclusive for living organisms and we can't create them we can't produce them or manufacture them but this was disproven by a single experiment by mr friedrich wooler he synthesized the urea in the lab and proved that organic compounds can be made without the involvement of a life process okay what did he do he had a mixture of ammonium chloride and silver cyanate and heated it this is a symbol for heat and it became urea urea was a white substance some silver chloride excess and this is the molecular structure nobody thought it would ever be created in the lab and that is why organic compounds can still be so and that is why we can say that organic compounds can be created in the lab it's not just exclusive to living things okay look at this pie graph can you find carbon where is it it would be hard to look at it because it belongs around here just a tiny bit oxygen and silicon are majorly abundant in the earth's crust these are usual these elements usually constitute the elements inside stones and rocks so because our earth is a rocky planet but this tiny carbon that's found here is the very essence of life and that is why it's called the element of life okay it is so small but why is it so special just why as we have observed a lot of compounds around us are made up of organic compounds ninety percent of the compounds are organic all those products that we use they're organic substances again organic the technical organic containing carbon okay why are there so many organic compounds on earth okay before we dive in let's get familiar first with our tools scientists have designed and have agreed on this rigid set of rules on how to view these molecules and how to represent these molecules and these are what they call the structural formulas we can have it presented in a ball and stick model an electron dot formula these are dots of electrons or a dash formula or a condensed formula or a bond line formula in a bond line formula each vertex are considered as carbon and the ends here is also a carbon and the h are not shown it's as simple as that okay let's look at the three familiar ones the structural formula the dashed line formula they're both similar in name these are the stick figures that you have seen so far for example we have carbon carbon carbon and connected by hydrogens this is a kind of a dash formula wherein you can see dashes surrounding atoms the type the number of dashes will be depending on the bonding capacity depending on the bonding capacity of that atom and we will learn later about the bonding properties of carbon the lewy death structure is this kind of uh representation wherein the valence electrons are shown around the element you still remember about the planetary model from niels bohr how many electrons does carbon have we have looking at the periodic table there are six electrons and how do we draw its arrangement inside our bits we have the capacity of two here remember and here we have the capacity to hold eight in the second shell remember but if you don't remember you can really review the formula for this one is two n squared okay because it's six and there are already two you can have four sitting in here that means there are four on its outermost shell i just didn't continue the circle but it's supposed to be a circle and this one too okay so the four are what you call the valence electrons valence electrons are the electrons in the outermost shell okay how about condensed formula looking at this looking at this structure that we draw number one condensed formula is that condensed version without the dashes and the h's are written around a single c for example the first c this one there are three h's around it so you just write ch3 and then the second c there are two so c h two and this one c h three so it is understood that it is written in this order structural formula shows arrangement this one order but sometimes it can still be written in another kind of formula that we call empirical formula or the simplest form this is the most condensed form so how many carbons are here three so just write three and how many h this is six eight c three h eight okay this is another kind of writing just remember this four the structural louisiana structure condensed in empirical formula all right let's go to the star of this lesson the atom carbon carbon is considered as the element of life as i've already mentioned a while ago there are four valence electrons surrounding it on its there are four valence electrons on the outermost shell it has six electrons at six protons and six neutrons the mass of 12 gram per mole the atomic number of carbon is so versatile that it can make long branches of compounds and different varieties and the reason is its bonding properties it's so unique that carbon can number one it can create three types of bonds three types of bonds the first one a single bond when we say single just one double two triple three look at this pictures one lines around so within a c one carbon to carbon there is one bond carbon to another atom you can make two and you can make also three in a single bond one pair of electrons is shared between two atoms when we say shared they're sharing it so both has it and for this one carbon has an electron here and hydrogen has an electron here and two pairs meaning they're sharing two per pair so let's just have a shortcut so let's draw first the lewis structure of carbon there are four dots around it this is the lewis structure of carbon four valence electrons are shown this carbon meets a hydrogen that has one electron because what hydrogen is the first element that has an atomic number of one and has just one electron as well and they and they tend to share this one as mentioned a while ago there are two and there are three elements try to follow this octet rule rule wherein the outermost shell must be fully eight so because it's four it needs four more so it looks for other elements to bond with so that it will be stable this is for stability the exception for this one is hydrogen because it can only hold two okay just remember that going back to c so c is looking for four more here it finds one hydrogen and the hydrogen is good enough to share its electron and these other electrons too would like to look for other elements and hopefully another hydrogen comes and they share these two and another hydrogen and another hydrogen and they shared these two and these are those sharing bonds or covalent bonds that means there are four more electrons that are being shared and if you count them all that would be eight and when it's eight it becomes happy because it's satisfied with the octet rule so this is a single bond how about a double bond a c having four valence electrons can meet another carbon which has four valence electrons it has the capacity to form a covalent bond here share these and another covalent bond here this is a double bond so these two here would look for other elements to bond with for example hydrogen [Music] and this one hydrogen this is an electron this one hydrogen and this one hydrogen part in my drawing so to write that to write that better you can write c one two okay and maybe some two lines here sometimes they're written in angles sometimes they're written in straight lines only both are accepted one up or down or upper side all are accepted you can have all or like this up or down up or down there's an edge here like that how about a triple bond so c having four could meet another carbon and could share these two here and share these two here and show these two here and this one goes looking for other elements to bond with say other carbon or maybe other electron other hydrogen let's do it again because it's erased okay this you can have another element or maybe another carbon here and so on but can you make four can you combine these these two and these two no it's not possible because the structure of the carbon inside its molecules it really just allows four up to three up to triple bond only just remember that okay in summary carbon can hold four bonds at maximum for but four bonds four single bonds but with carbon to carbon it can only have a maximum of three okay only three not so much okay three let's go next so having these three types of bonds you also have their characteristics observe the numbers one five three point five picometers one three three point nine picometers um picometers 120.3 picometers yes picometers okay if it comes shorter right short term it gets shorter and more bonds are here now three two yes so as you go from here to here it becomes shorter but actually it also becomes stronger it would be harder to cut these buns a lot more than having these two being cut out so it's stronger and shorter but shorter then another property is that carbon can make this kind of arrangement so there are different kinds of arrangement of molecules and this one is for single bonds when carbon makes single bonds full four single bonds it tends to arrange in this kind of arrangement a tetrahedron so there are four there so these um four hydrogens are trying to say as far as possible because they tend to repel each other because of this electrons that are present around them but at the same time this whole atom is holding itself amazing right okay lastly this amazing property of carbon can have it carbon can connect with not just itself but also with other elements too so you can have this so look at that the first level these are the lewis structures of different elements that can possibly combine with carbon to form organic compounds so the first one we know that carbon has four valence electrons and nitrogen how many electrons that does nitrogen have nitrogen actually has nitrogen has seven but because the two are on the first level on the outside it's just a remainder of five so it has five five valence electrons next oxygen how many electrons does oxygen have and look at it in the periodic table the atomic number that indicates the number of protons and the number of electrons oxygen has eight so let's draw the planetary model again it's always two in the first level and a maximum of eight and the third and the second so two needs six more one two three four five six okay so there are one two three four five six six on the outside six valence electrons so when we draw the lewis structure it would be one two three four five six like that next hydrogen hydrogen is the first element in the listing of the periodic table is just has one one proton one electron that means it just has one electron sitting on its first level first energy level okay and it's ready to share that very electron it's very kind then x how about this x what element is x is it xenon is it no there it was written that it has seven valence electrons looking at the periodic table the halogens on the last part of the periodic table the halogens the fluorine chlorine bromine have their group number 7a so these actually refer to the halogens what are those halogens we have chlorine erase again halogens those fluorine chlorine bromines bromine and iodine or iodine okay so these have a remainder of seven at its last shell so it has seven and it can only share now let's look at their bonding capacities carbon has um just because they have these valence electrons it doesn't mean that they can share all these so for carbon it can share all four so it makes four so it's so it is possible for carbon to have four but nitrogen even if it has more freelance elections it can only share three so it's not always okay these two tiny um elections here nadilli marshall that is what you call lone pairs or unpaired electrons lone pair it wants to be on their own these are gonna hand share so nitrogen has a bonding capacity of only two with this two lone pairs that are imaginary they want to have it their way how about oxygen oxygen also has lone pairs and two pairs this one and this one it is able to share only two the two are around here how about hydrogen well hydrogen is so kind to share all that it got so is sharing and then this one again these are the fluorine chlorine bromine iodine iodine okay it also has three that is not shared and it only shares one okay accepted all right here's the summary carbon can form four covalent bonds covalent to share with no unshared pairs three covalent bonds for nitrogen with one unshared pair two covalent bonds for oxygen and two unshared pairs one covalent bond for hydrogen no unshed pairs and the halogen x fluorine chlorine bromine iodine normally forms normally formed so there are other situations can deal with foreign covalent bond with three unshared pairs of electrons pairs of electrons review you just have to remember this the little member is carbon it can make four next nitrogen it can make you can pause the video if you like three how about hydrogen it can make one by the way you can write it this way or this way whichever way and this one too then how about oxygen it can make two or you can write it this way double bond maybe a double bond or a single bond oxygen is capable of double bonds too remember this so oxygen can make single bonds and double bonds we're done i think it's just the remaining fluorine so if it's fluorine it can make a single bond only if it's chlorine it can make a single bond if it is bromine it can make a single bond and then if it's iodine iodine you can make a single bond we will see later at the examples on how these bonding works