again it's on the video i put it there but i'm going to say it one more time here matter you have pure substance and you have mixtures there we are not going to look into the mixtures more you have elements and compounds right so far we have seen this now elements are of two types one we call it atomic element another is a molecular element it is very important to differentiate molecular element we also have a compound called molecular compound so if you simply say molecular that's not enough you have to say whether it is molecular element or a compound okay now every element in the periodic table they are atomic element except seven okay and those seven are usually given at the bottom of the periodic table right here you see it it's right there those elements are molecular elements now if i wanted to know you supposing if you are given a periodic table without this information it's easy to find you take hydrogen okay then from nitrogen you move three steps nitrogen oxygen fluorine and then go down three steps chlorine bromine and iodine okay so those are the six elements hydrogen and then you start with nitrogen go three steps nitrogen oxygen fluorine go down from fluorine go down three more which will be cl2 br2 i2 and that's what you see it at the bottom you see that h2 n2 o2 f2 cl2 br2 i2 those elements are called molecular elements every other element in the periodic table is an atomic element so this is possible like you will see if i give you a choice of like four elements and i ask you on the following which is an atomic element which is a molecular element okay very simple all the elements in the periodic table they are basically atomic element except seven of them those seven i told you where to look for so that's about elements so what about compounds so now compounds are of three different types and that's what we are going to see in this class okay so i am going to take this compound and then split them further here compounds are of three different types i can say something is an ionic compound i can say something is a molecular compound and i can say something acids so these are the three broad classification of compounds again what do you mean by compounds means atoms of two or more elements combining that's what compounds are okay so i have an ionic compound molecular compound and acids those are the three different types of compounds now how do i know this now that we are doing looking at this these different classes how do i do this now remember we know that a general classification of elements in a periodic table how are they classified metals non-metals and semi-metals is that right that's a general classification we saw that from the previous chapters metals non-metals and summatives now in order to make a compound how many minimum elements i need at least two is that right i need to have at least two elements yes the two elements combined water hydrogen and oxygen minimum two so i know the elements are basically split into these two groups three these three groups metals non-metal semi metal right so if i take two elements what are the various way i can combine i can combine a metal with your metal is that right i can combine a metal with a non-metal i can combine a metal with a semi-metal what are the other possibilities i can combine a non-metal with a non-metal i do not have to say non-metal with a metal which is already there and non-metal with a non-metal a non-metal with a semi metal and what other combinations i can have a semi metal with a semi meter right because semi metal with the metal is already here semi-metal with the non-metal it is already there you don't have to repeat so if i take two elements minimum remember compounds come with three four elements coming from three elements four elements so on and so forth okay the minimum amount of elements you need is at least two so within the two i can have this many combinations right but luckily for us what we are going to do here is of these three combinations of these six combinations we are going to take only three this is ruled out we are not going to look intimate that's why somebody you know just told me right if you have two metals how do you write it the general rule is you write the metal to the which it comes on the left side first okay we don't look into metals and metals we look into metals and non-metals if i have metals and non-metals i call it ionic compound okay now metals and semi metals we are not going to look at it now of these combinations semi metals and semi metal we are not going to look at this so these two are called molecular compounds okay now usually you will ask me like how do i know acids then acids usually start with hydrogen and there are a little more rules to follow okay but then acids we will treat them separately i'm going to look into this much more closely before i come to acids okay so um if you have a metal with a non-metal it's an ionic compound if you have a non-metal and non-metal non-metal enzyme metal they are called molecular okay so once depending on these the naming differs if it's an ionic compound you say the names in you are going to apply a rule for ionic compounds in order to come up with your name if i know something is a molecular compound i am going to apply the rules for molecular compound to get the names now they are not totally different rules some rules here we don't follow that that's all nothing nothing uh like thought it's not going to be totally different and if it's an acid how do i give a name like i said acid i will come to that later not now okay so what i'm going to do is i'm going to write a few formulas and i expect you to tell me whether it is an ionic compound or molecular compound we are not going to worry about the name just as an exercise okay so whether we can found find something as a molecular compound or ionic compound okay here there is a skill builder test given here a skill builder exercise given under example 5.4 okay some examples are given here i have this this is one sample one formula the other one is this and the third one is this now this is an element right because how do i know this has through two letters this also have two letters then you will be wondering like how do i know this if it's a compound both of them written in uppercase if it is one is written in uppercase one is written in lowercase then it is a an element that's why like i i sometimes there is an element called cobalt in the periodic table you write it like this there is also a compound called carbon monoxide it is very very important to know the difference you cannot loosely write one for the other okay so if i ask you to write the carbon monoxide this is the formula if i ask you to write the name of a cobalt this is how you do this both have only carbon and oxygen now if i have a bigger bigger letter uppercase and a lowercase this is an element if i have both of them uppercases it is going to be a compound because compound elements coming atoms coming from two different elements very important to understand okay so don't think anything more than one letter it should be a compound not necessarily it's very important that's why like when you write it sometimes like this i said i just circulate and say i don't write it like this because it is a big deal this is a compound this is a an element so now let's take this and this how do i classify this now the first thing i look at is i'm looking at two elements sodium and oxygen now if you have a metal that will be the first part first element the metal will not become the number down the line i look at the first element if it's a metal and i look at the second one which is going to be usually non-metal so this is a metal this is a non-metal how do i classify it's an ionic compound okay this is nitrogen and oxygen nitrogen is a non-metal oxygen is a non-metal both are non-metal so it's a molecular compound that's how i say that okay so let me give you a few more examples so let me write down the rules here ionic compounds means metal with a normal molecular compound is a non-metal with a non-metal or a non-metal with a circle okay now remember if in cases we are only talking about two elements you may have a formula with four or five different elements if it's an ionic compound there can be only one metal say for example baking soda the baking soda we use is this all right the common name is baking soda but the chemical name we will come to that here you look at this how many elements i have one two three four elements that means this compound is made from four elements if you happen to have a metal you can have only one you can't have more than one sodium is the metal the rest of them are non-metals very important to understand okay so you won't have sodium magnesium aluminium like the aluminum like that never like that don't question yourself like that okay i'm not going to give you any trick question like this with involving more than one on metal okay so i trade the first element which is metal here the rest of them has going to be treated as one group i'm going to treat them as one box which i call it polyatomic ions which is given at the back of the periodic table okay so what is this compound ionic sodium rest of them are non-metals supposing if i do this one p2 s5 both the phosphorus and sulfur are non-metal so it is a molecular compound the rule is if if i have to make it very simple i look at the first element if it's a metal it is ionic if i don't it's the chances are it's molecular now the acid starts with the hydrogen will come to acid later okay so usually it's very easy to remember okay you don't have to so i look at phosphorus phosphorus is in group 5 it is a non-metal so it's not an ionic compound what else it can be it's a molecular compound okay so i look at this one i have one carbon and four chlorine atoms look at the way it is written there c this is c and l this is the symbol for because when you write it like this you are saying i have a compound with three elements one is c another is c another is l it creates a confusion you can write the same two elements like this if it is two c you have to write c two right very important to understand when you write the symbols you may think that it is not it's not going to make a difference it does make a difference here this one confuses you that you have three a compound with three elements two of them have the same symbol you don't write it more than once here it clearly says i have one element here one element there how this is a smaller letter this is an upper case letter so this is carbon is a non-metal chlorine is a non-metal both are non-metal i don't see metal so it is a molecular compound okay sodium chloride sodium sorry we all know that but there is a rule how to follow this see here i see a metal it's an ionic compound okay metal the moment you say metal you can you can just pinpoint oh it's an ionic cup okay now there are i don't want you to apply this rule two steps after you take two forces down the line you cannot do that where you will see more examples where in which you will see compounds without a metal but they are called ionic compounds okay now this is an intro class so i i have to treat you like we have to only go within that sector okay so don't go and talk to another professor my professor said like this and then you say no he said like this you are wrong something like i'm talking for this class m101 and that's making it easier there are some compounds okay which are called ionic but you don't see a metal those are exceptions to the rule we are not looking into the extreme cases here uh the reason why i'm saying this is this is a face-to-face class no problem but you do see sometimes from an online class where they said i spoke to a professor he said like this why you are saying like this i think probably they don't they have a lot of time in their hand they try to like i address to the class okay it is not that i am telling what i know i'm only trying to say what is needed for this class okay so make it easier for you so here it is non-metal this is a non-metal so it is a molecular form okay so you know the difference now the difference between ionic and molecular if i see a metal it's an ionic compound if it's a molecular compound i don't see the metal i'm making that rule very simple now the way you the book presents the information here is they deal with ionic compounds all the way and then they come to molecular compounds next and then they come to acids now what i'm going to do is i'm going to slightly change the order why because with molecular compounds you have to come only with the name nothing else for ionic compounds given two elements you should know the formula first you have to derive the formula and then come up with your name that is lot more involved okay and then acids are a specialized type of compounds which comes last so what i will do is in order to make this transition easier for us molecular compounds naming the molecular compounds is very easy okay and that's what we are going to do first so i'm slightly if you happen to look at the class notes or something like this you might be wondering like why this is keeping ionic component i will come back to ionic compounds let's look into the molecular compound because for molecular compounds we need only the names we don't have to like we don't have to say how i got this formula we don't have to know but you will be given a formula you come up with a name if you are given a name you should come up with a formula that's all it is whereas if i if i give a metal with a non-metal you got to be careful to get the formula right okay sodium chloride is nacl right sodium oxide is na2o how do i know this there is a rule to follow there okay that's why we are going to come to ionic compounds a little later so let's deal with this so when i try to write the name the name is uh the technical what is the technical term anybody remembers what did they say what's the technical name for naming nomenclature because sometimes i will say that write the names of these compounds that's how i do this if you see it in a common final exam say what is the nomenclature of this they try to put a very specific word there and i want you to understand nomenclature means name okay okay now the first thing is when you name what is the rules for molecular compounds you say the name of the first element as it is from the periodic table the second element you have to change the name a little bit that is you have to change the name in such a way it ends with i d e the name of the first element is written as it is okay the name of the second element must be changed into ide in this case sulfur will become sulphide okay this is sulfur right sulfur becomes you drop this like what is that you are and it becomes sulphide this is chlorine chlorine drop those two letters and then replace it with ide chloride fluorine is fluoride sulfur is sulphide like that okay so and what else nitrogen is nitride so basically if you have the second element the name should be changed to ide and what else you need to know about molecular compounds you have to use prefix what do you mean by prefix you have to specify how many atoms of each kind is present okay now the prefixes are given in this right here do you see the prefix for one it is mono for two it is die three is try like that so i have it on the periodic table you will have it till uh the final exam the final exam if they give it that is fine otherwise you need to know this uh from 1 to 10 mono diet try tetra like that it's very easy to remember but for now till the final exam you will have this periodic table all right so in order to name them we write that we say the prefix followed by the name of the element prefix followed by the name of the second element okay now there is one little rule where you may you may stumble across is if the first element happens to be only one atom we don't use prefix in all other cases we use prefixes let me make it very simple okay so if you are given a compound and if you find out it is a molecular compound the way to do that is the order is this prefix for the first element name of the first element which is written as it is prefix for the second element and the name of the second element should end with ide okay so having said this now i wanted to try the name for this one i have two elements here two atoms here right phosphorous two so i say di and then this is phosphorus so i'm going to write it as it is diphosphorous okay and then the second element 5 penta if you look at the periodic table it will say penta sulfur becomes sulphide so it is penta sulphide diphosphorous penta sulfide that's a name okay so let's try the name for this one the first element has only one atom so i won't use the prefix for the second element there are no restrictions you have to use the prefix okay so the here i won't say mono carbon i will simply say carbon now for four what do we say tetra table with you tetra chloride so that's the name okay carbon tetrachloride so we have these bases in between those or no oh they should they will be one word or keyword or yeah no no it will be written as one word because i didn't have the space i may go out of the camera so i wrote it like this it's all one word okay so both of them have carbon and oxygen right but one has one carbon one oxygen one has one carbon two oxygen so i got to make sure that i know the names for this so what is the name i give for the top one anybody can you try the first element is only one carbon carbon monoxide very good carbon monoxide carbon now remember mono oxide but if you have two hose you can drop one of them so basically you can write this as carbon monoxide so what should i say for this one anybody um carbon dioxide very good carbon dioxide so naming of you see that i want to get into this chapter slowly so that you get your like you are able to understand this that's why i started with molecular compounds carbon dioxide okay so this is how we name the molecular compounds the rules are the first element is written as it is the name of the second element is ide it should end with ide the second rule i have to remember is for the first element i if it is one atom i won't use the prefix for the second element i have to use the prefix whether it is one or more it doesn't matter okay let me write a few examples here and then i'll ask you to come up with your name and uh what else we all know water is this water also has a chemical name we are going to try this today and let me come up with some names here some names some formulas i have given okay so we are going to look at these names and then i'm going to stop okay and then when we come back next time it is going to be ionic compounds okay so let's try some names here now i want i don't want the same person answering i would again this class they interact pretty well they are actively involved and so i don't want the same person trying so i want different people trying this again don't be like worried like because it's getting recorded i am telling you like i don't want you to think if someone gets it wrong like it is it is that attempt nobody rode your bicycle the first time you got and you went there nobody walked straight right when you started walking the same thing applies here we do make mistakes and then we correct ourselves that's why we are doing this as a class so let's try this the first one anybody can you try the first one is it um chlorine monoxide no you are almost there what else i should do you are missing at the prefix be before chloron chlorine yes dichlorine monoxide because this is two i have to use the prefix dichlorine so someone else can you try this one what is this the second one see it doesn't take me like 40 seconds to finish this but i don't want to rush like that i wanted to give you a chance so that you can you can try to do this i i believe that you are hesitant that you may make a mistake and all it's okay this is it's in the learning process that's how we do this if i have to learn french i i do not know how to write those words or feminine gender or everything has a gender right in french is it um sulfur trioxide it is sulfur dioxide here i don't say mono sulfur it's a sulfur trioxide everything is together i'm just giving it a like splitting it so you can see it okay we all go to restaurants and have water so next time when you want a glass of water you are going to say this name to whoever is waiting on your like in the restaurant so what's the name i should give for water anybody now let me not put the pressure on you like do this you can pick any one of them answer this because we are done with these two pick anything else so let's call this this is one this is two this is three four five six so pick any one we are done with one and two already okay so let us save some space here so one and two we are done already so let's try three four five six i give you a choice pick any one of them is three hydrogen dioxide uh now dioxide means there are two oxygen is that what you see on the board is it dihydro hydro monoxide dihydrogen monoxide okay because this is hydrogen we have to say that this is more than one so i have to say dihydrogen oxygen is one so i have to say monoxide if i say hydrogen dioxide we are saying that remember the prefix comes before the name of the element right right so it'll be it'll be the two behind the o instead of the h if so we're [Music] let's say for example if i give you a formula h42 what is the name you should give anybody instead of hydrogen dioxide yes we don't say monohydrogen remember that is very important hydrogen dioxide okay so water is dihydrogen monoxide now you know the chemical name for water right um number five is silicon dioxide very good silicon silicon dioxide silicon is a non-metal sorry semi-metal semi-metallic a non-metal is a molecular compound again silicon dioxide now remember silicon is to the left of oxygen so that's why we write it like that number four is it um iodine my mono chloride very good see this is this is what it makes the instructor very happy like when you get that that's basically like what what really excites me instead of me saying the holy name okay so this is iodine very good whoever said that iodine monochloride i also want you to pay attention here iodine and chlorine both are halogens on the seventh group right there on the seventh group you see that iodine comes below chlorine that means i should write iodine first that's how we write the formula so iodine is written so also pay attention to each one of them how the formula is written the one which comes on the left should be written first if it's in the same group the one comes below should be written first okay metals if you have metal metal should be written first okay so this is uh iodine monochloride i don't write this as cli if i write cli supposing let's say for example instead of ir icl if i write cli how different the name will be it will be chlorine mono iodide is right the naming changes you may think i can flip the formula symbols it's okay no the naming completely changes here this is chlorine mono iodide this is wrong here it is iodine monochloride they have the same oneness to one but the way you write the naming differs okay now remember i can give you your name and you should come up with the formula it's very easy in a molecular compound it's very straightforward when i give a name and ask you to write the formula so what is the name right here the last one i mean that nitrogen monoxide very good nitrogen monoxide nothing makes an instructor more happy than the class is actively involved okay nitrogen monoxide okay so um let me give you a few names and see whether you can write the formula nitrogen oxide sulfur hexafluoride and then what else phosphorus now i have given a name so what should i do i have to i want you to write the formula for that okay now this is nitrogen it says die so i should write 2 right penta oxide so it should be oxygen pentium is fine so this is the formula n2o5 can someone give me a formula for this sulfur hexafluoride what should be the formula s um so um s f six okay now this is made this one here student sometimes things fluoride formula is sfl if you write like this you won't have my mercy i will mark it 0 because you cannot change the name of this right you cannot change the symbol there is no element called ff that's florida not fluorine okay very very important so you write sf6 many many times i see them they write it like f5 no that's wrong don't assume you have a periodic table why do you have to assume so this is sf6 for right what is this one p uh-huh c uh capital c small l three okay all right pcl3 that is a phosphorus trichloride so now you got the names for molecular compounds is that right so you won't have any problems uh writing their names and the formula molecular compounds now i'm going to let you go by saying just this one for ionic compounds how do i name it we have to get the formula first that is a different uh challenge okay but in ionic compounds the most important rule to write remember is we do not use prefix ionic compounds don't use prefix at all okay so just to give you an example we all know uh salt is nacl if it is a molecular compound how i would have named it sodium monochloride something like that right not in ionic compounds in ionic compounds no prefixes whatsoever i will simply say sodium chloride okay the most important difference between the nomenclature of molecular compounds and ionic compound is this here i don't use any prefixes whatsoever for ionic compounds okay so that's the topic uh for the next one where you will see we will deal with ionic compounds and once we deal with ionic compounds we have something called acids and that will be the end of this chapter okay and let's see i'm going to