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0:05
okay in this video we'll be talking about coordination compounds so last video we saw what are transition elements what are their properties and how electronic configuration essentially controls their properties and their interaction with different elements in periodic table so in this case we'll talk about different types of compounds that these transition metals can form and one of those compounds is called the coordination compounds or coordinate compounds
0:36
so up until now you guys have learned about two different kinds of compounds one of them being the ionic compounds which is formed between a metal and a non-metal and then there are molecular compounds uh which is formed between two non-metals so for instance ionic compound is like sodium chloride nacl na is a metal cl is a non-metal so that makes it ionic here they essentially transfer electrons from one atom to another which makes them ionic
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and the bond that m is keeping these two atoms together is an ionic bond um the other kind of compound is molecular compound which is composed of two non-metals for instance if we talk about water h2o hydrogen is a non-metal oxygen is a non-metal so that essentially makes that compound a molecular compound now the kind of bond that keeps the
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atoms in a molecular compound together are called covalent bond so in that case both the atoms that are bonded together to each other by a covalent bond are sharing one electron each so they're they are sharing electrons together to fill up their octets uh coordination compounds are the compounds where one of the uh atoms kind of donates to a lone pair to the other atom and that kind of bond is called a coordinate bond where the electrons essentially like a
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lone pair is completely donated so today we'll talk about coordination compounds what you what you see right here this is an example of a coordination compound so it every coordination compound how can you identify it you would see that there is a certain part of this compound a certain formula of this compound would be written in square parentheses okay so whatever is written in square parentheses that is called the complex part of that compound
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so for instance what we have here if this is a compound it consists of this part in parentheses
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and a certain part which is outside the parentheses so then we have co nh3 whole 6 in parentheses and cl3 outside the parentheses so whatever is inside the parentheses for instance between this is called the complex
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ion whatever is outside the parentheses is called the counter
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ion so but essentially this means in this case of a compound this complex ion is acting as a cation
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right so it consists of cobalt and ammonia and this is a whole ion in itself so up until now you guys are familiar with some polyatomic ions right
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i'm just going to put an example right here this has nothing to do with coordination compounds okay i'm just trying to explain you uh like for instance right here if this sulfate ion is a polyatomic ion which means that it consists of multiple atoms similarly what you see right here co nh3 hold 6 is a coordination complex or complex ion this is also polyatomic ion right and this is just a complex ion it's called a complex ion y because it consists of a
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coordinate bond which is formed between cobalt and ammonia and this will make more sense as we talk about this but essentially it consists of this ion which is called the complex ion so whatever is included in square parentheses is a complex ion always remember that it can be cationic it can be anionic in this particular example it is cation so whenever we write a formula remember in chemistry
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it's always cation followed by anion it's always cation written words for instance fcl h plus cl minus cation is the positively charged ion that is the one that is always written first nacl you can pick whatever example you want it's always cation followed by an answer in this case also we have the cation written first in this case cation is a complex ion how do you know that because it's in square parenthesis so always just remember whatever is in square parentheses is
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part of the complex ion and whatever is outside that is the counter line now again counter line can be positively charged negatively charged depending on what compound we are talking about
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now this is about uh where we're talking about the complex ion right in a coordination compound now let's further uh break this complex ion down so what we have here we have chloride ion you should know how you name cl minus that is a chloride ion this is the downtrend and this is a complex ion now let's break apart our complex ion it consists of cobalt parentheses ammonia six and if i break this apart it is going to be three plus and i'll explain you
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why i have three plus here but anyways let's just see what i'm uh want to express from here for now essentially it consists of a metal which is going to be always a transition metal
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so in this case that is cobalt and then whatever is outside or whatever is apart from that transition metal is called a ligate so there is always a transition metal and there are going to be certain amount of ligands now that can be same ligand multiple different kinds of ligands in this case the only ligand that we have is ammonia okay so what does a coordination compound consists of it consists of a complex ion which is always going to be in square parentheses and
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a counter ion now it's not necessary if it has a counter ion or if it's if it's a compound it will definitely have an ion but if it's a coordination ion it would just give you ion like this
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and the next thing is that in a complex ion it will always consist of transition metal and everything else apart from the transition metal is called the ligand now what do these ligands do these ligands essentially are
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donor of electrons
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so remember our metal is always positively charged metals are always cationic in nature they are always looking for electrons so in order to make this compound these ligands they donate a lone pair of electrons so they always have an extra lone pair and that lone pair is donated to the metal ion and that forms a coordination bond that's why these complexes are called coordinate complex coordination complexes or coordination compound
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so let's take a look at the definition of a ligand
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so the ligand of a complex ion are the molecules or anions with one or more donor atoms each donor atom donates a lone pair of electrons to the metal ion to form a coordinate covalent bond so the bond between coordination compounds remember is called the coordinate covalent bond both electrons in the shared pair come from same atom and what are these vegans these legions can have multiple different kinds so you will have to kind of memorize that there are
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and some ligands that are called monodentate monodentate means mono means one dent means teeth so when you write a coordination compound you usually assume that if this is the metal in the middle this is my transition metal it has formed coordination bonds with multiple ligands and each of these ligands essentially forms a bond with the metal just like it's
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acting like a teeth for this particular metal so that's why it's called dentate mono means just one vegan mono dented ligands are the ones where one ligand for instance if i have this metal m and this ligand l one ligand will be forming a bond with metal only one bond so each ligand can only form one bond that is a monodentate lead what is a bidentated ligand a bidentate ligand is going to be something which has two donor atom for instance if i have this uh ligand which is let's
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say en okay en can have two different coordination bonds so the same molecule can form two bonds with metal so that's why it is called a biodentidian so it has two teeth two teeth with help of which it can interact with the metal and then there are polydented ligand which means that this particular negan will have more than uh two donor atoms so it can form multiple bonds with the metal so one single ligand can form multiple bonds with the metal so that is a polydentate legend
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in the coordination compounds and you need to be able to differentiate between these compound you should at least know their names i don't expect you to know their formula for not for at least these funds in the bottom but you should definitely know their names
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and you should be able to recognize them when you see their formula written out but i don't expect you to know their formulas by heart so the more oriented league in examples would be water so if you see water has oxygen oxygen has two different lone pairs and it can donate one of these lone pairs so it can only form one monodentate bond one bond with the metal in coordination compound that's why it's called monodentate then this fluoride ion fluoride ion also has multiple
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lone pairs but it can only make one bond so f minus you should know their symbol for at least the top ones these are these are the easy ones these are polyatomic ions that you should have already known their names and their formulas by now then there is cyanide ion cyanide ion also has
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the extra electron lone pair that it can donate um now there are um the next example is hydroxide ion hydroxide would be o h minus cyanide would be c n minus then there is ammonia which is nh3 chloride which is cl minus thiocyanate which is scn so essentially instead of cn it is scn minus here thiocyanate can form a bond with either the s so it has two atoms that can donate electron either s will donate the electron or n now either way it can only form one bond with
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the metal because it's a mono-dented vacant next example you see here is nitrite which is o n o minus so here also again nitrogen has a lone pair that it can donate and oxygen has a lone pair that it can donate but idea is that only one of them will be donating electron at one time point now let's look at certain examples of bi-dented legion first is ethylene diamine which is also abbreviated as en so you should know its name ethylene diamine ethylene means f means
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two eth ethylene or ethylene means two carbons so what you see right here two carbons and each of these carbon is interacting with one amine so that's why it's called dye amine because this molecule has two amine molecules amine is nh2 so this is a structure of ethylenediamine what you should know sometimes when you're writing the structure it can be abbreviated as en so instead of writing the formula you can just write e n and make two
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different bonds and why can it make two bonds because there are two nitrogen or two amines that each of them has a lone pair which can interact with metal to form a coordinate bond so this ethylenediamine one atom will be forming two bonds with a metal in the middle similarly there's another example of identity legion which is oxalate oxalate is essentially c two o four two minus so you can see the formula can be written out as simple as that c 2 o 4 2 minus
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that means it's an oxalic ion and each oxalate ion will be forming two bonds with the metal two coordination bonds with the metal two of these oxygens essentially can donate one lone pair each
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now certain examples of polydented ligand means so you can see right here when there's only one nitrogen in ammonia it can form one bond when there are two amines two nitrogens it can form two bonds now if i have multiple amines for instance in here diethylene triamine so there are diethylene so two ethylene groups ch2 ch2 two of those and triamine means three amine groups so therefore each of them can form a bond so it is going to form three points with the metal then you
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see triphosphate which again can also form three bonds each of these oxygen can form one bond with
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the metal ion this is triphosphate
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next you see ethylene diamine tetra acetate ion which is also abbreviated as edta this is a very popular compound which is used as a chelator we'll talk about that in a little bit but what does it do each edta molecule is four minus and it can form multiple bonds so you can see right here one two three four five and six so the highlighted ones highlighted atoms are the ones that can each donate a lone pair to a metal so it can form one two three four five six six bond one if
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edta molecule can form six bond with the metal so it can donate six lone pairs to the metal at one
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point therefore it is called polydentate so you should know their names by now there's water ammonia fluoride chloride cyanide thiocyanate hydroxide nitrate and examples of dye or biodentate is en ethylene diamine and oxalate which is c2o4 2 minus and lastly is polydented for instance diethylene triamine it can form three bonds triphosphate it can form three bonds and edta italian diamine tetra acetate ion which can form multiple bonds even as of
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each edt okay now i said to you there is a term called chelation edt is a very good chelator that is used in chemistry what is what do i mean by chelation chelation essentially means that when you have a certain compound or certain ion like this it has so many teeth that it can interact with the metal and kind of engulf that metal inside of it that is called the chelator something that can essentially just
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interact with the metal and kind of engulf it so remember i said that each of these metal will form one bond with the ligand right and there are some ligands that can form multiple bonds some ligands that can form two form two bonds one bond or multiple bonds so if a ligand can form bidentate or polydentate meaning if it can form either two points or more than two bonds then those ligands
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usually can form the ring around the complex ion so for instance if i'm making a complex between cobalt and en en was abidented ligand ethylene diamine so for instance right here you see co again each of these remember can form two bonds so i have one en and you see here three en so one two one more en and then one and two one more en so i'm not writing the complete formula i'm just writing en which also means that i understand this it's ethylenediamine so this ethylenediamine you
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can see how this ethylenediamine has all its teeth each of the ethylenediamine has its two teeth on cobalt so it kind of has engulfed this cobalt it's not going to interact with anything else that's called chelation the process and this com these and legions are called chelators
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a complex ion containing this type of structure is called chelate because the negan seems to grab the metal ion-like claw so it has kind of like stuck the metal with an instructor next example is you see here right here edta right each edta has six donor atom and form very stable complexes with metal so you can just imagine that one edta molecule can form all these six bonds just one atta molecule so it's a very good key later it can interact with the metal and just
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keep it attached to itself and does not let it go or interact with anything else
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now i already explained to you that the components of a coordination compound for instance right here in this example the square parentheses are written first and the ion is written at the end which means chloride ion is the anion in this case cl minus and then this co nh3 whole 6 to the power 3 plus is our
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counter ion or the complex ion in this case so and how many ligands are there in this case there are six ligands so there are six ammonia which means there are six medium that are interacting with cobalt and if i look at the other example which is k2ptcl4 so if you look at this example how can i dissociate this whatever is in the parentheses remember that is our complex ion so in this case it's going to be platinum times cl4 and then since i'm breaking it apart it has to have a
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charge right so we'll figure out what the charge is later on but right now i have potassium ion which is k plus and then we have this ion which would be what would be the charge here to minus
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how do i know that remember when you make the um when you go from the ions to their structure um to their chemical formula that's how you do it if how do you get nacl as nacl because you have na plus cl minus so you cross these charges over to get to nacr right how do you get mgcl2 mgs mg2 plus cl cl minus 1 so you cross over these charges without the sign everything is positive and that gives you
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the chemical formula it's exactly like this here this is the cation now this is and i and so the whole charge of the compound is zero it's a neutral compound right there's no charge charges are usually written as a superscript on the right side there's no charge which means potassium
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is the ion and remember potassium belongs to first a group it always has a plus one charge so there are two of those so two times plus one plus the total charge of the compound it consists of this platinum chloride which we are interested in figuring figuring out what is the formula for it so i'm just going to assume it's x there's only one of those is equal to total charge of 0 which means x is going to be to do this i'll have to subtract
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2 from on both this side that would give me x as minus 2 that's how i know what is the charge on platinum ttcl4 right so those are coordination compounds now there's another term which is called the coordination number what is it the coordination number is defined as the number of bonds that are formed by central meton ion directly with the ligand now there can be uh uh different ligands that are involved or there can be just one ligand that is involved in a
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coordination bond but the idea is what is the total number of bonds between the center and the ligand between the metal and the linen that is a coordination number that's all
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so for instance if i pick this example what is the coordination number of cobalt in this so cobalt is right here now remember whatever is inside the parentheses is a complex ion so now we have to figure out if i were to think of the structure i have cobalt in here then there is one cl one cl and this is bonded directly to cobalt how do i know that because it's all in parentheses as long
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as it's all inside the square parentheses it's all directly interacting with the metal ion so first thing you should identify this is my metal and have two different types of ligand one is chlorine and the other one is en which is ethylene diamine so there are two chlorine so i drew two chlorine electrons right here right so i draw two different chlorines now what the next thing is i need to draw two e and again remember en is a bidentate leaking which means if i have one uh
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molecule of en it will form two bonds with cobalt so i can have one more em it's going to form two bonds with what so each of these en will be forming two bonds so now what is the coordination number coordination number remember is the total number of bonds that are formed by uh the central atom irrespective of what negan it is so total bond is one one two one three one four five six so total number of bonds is six so coordination number is
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six very simple as long as you just understand the terminology and how to use it
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so now i will talk about actually let's just talk about the coordination number and shape of some of these complex ions so again like you have studied before the all the compounds read molecular ionic they already have they always have a shape or a geometry that they follow and that geometry is dependent on how many bonds are present how many atoms are interacting with each other how many atoms are charged how much charge total charge is present so ah for instance right here if
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uh and a complex sign only consists of one metal and two ions uh two uh ligands sorry i shouldn't say i own two like legions interacting with it it's going to be linear
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if something has a coordination number is four there are two possibilities and are possible one is square planar other one is tetrahedral so i don't expect you to kind of memorize this all um the whole thing here but one of them is square planar the other one is tetrahedra and the last one is the coordinate number of eight if it's eight it's essentially
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would have a geometry of octahedral structure and here are some of the examples okay so you should just know if it's two coordination number it's always going to be linear if it's six coordination number it's always going to be octahedral if it's four it can be between square planar or a tetrahedral structure square planar is usually
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now let's not get into it right now if we want to discuss it we'll discuss it later in the slide
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so what do we know for a coordination compound as of now we know that it can consist of three different scenarios one is where it consists of a complex cation so whatever is in the parentheses is going to be written first with simple anionic counterparts and whatever is the counterpart will be written outside the next example is a complex anion with simple cationic counterparts so for instance the
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counter ion is going to be written first followed by the parentheses uh which consists of our uh
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coordination ion complex anion so it consists of these two scenarios there is also a third scenario where we have a complex cation and a complex anion for instance this complex cation is also complex and n is also complex so that is also another scenario that is possible i will not be dealing with that third scenario in your course we'll only stick to the ones which has a complex ion as a cation or the complex ion is acting as an anion those are the major two scenarios
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okay
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now we come to um two different things there are actually three things that are very important in this chapter that you should understand one is how you can figure out what is the charge or the oxidation state or oxidation number of the metal ion
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the second is that we should be able to write the formula of a metal i a transition compound if i know the name and the last thing is i should be able to name a coordination compound if i know the formula so those are the three things that we'll try to focus on so the first is how can i determine the charge of the metal ion that is present in a coordination compound now remember the metal ion will always carry a positive charge if it
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if you for some reason are getting a negative charge of just the metal ion that means there is some error you should go back and check your work okay so let's see how we can figure that out for instance this is a compound cobalt ammonia 4 cl2 i'm not talking about the actual name here because we haven't learned that yet so in this case what you're going to do how would you find the charge
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of the metal it's exactly the same idea that we do for any ionic compound so what is the total charge of the compound here zero how do i know that there is no charge written on the right superscript charges are always written on the superscript at on the right side of the uh formula so there's nothing that means zero and whatever is the charge of the complex is equal to charge of the metal ion and the total charge of the beacon in this case it has broken let's first break
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the total uh compound so we are going to break this into ion the first ion would be
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co nh3 hole 4 cl2 parentheses minus ncl sorry plus ncl minus how do i know that because cl is going to be dissociated cl always carries a negative one charge so if that is negative one there's only one ion and there's only one complex ion that has to neutralize the charge of this chloride which means it will be plus one now once i have this ion i can um assign each of these
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entities or each of these atoms that is present inside the complex ion with a uh charge or the total oxidation number and that is going to be equal to the total charge of the ion which is plus one so this consists of two things one is the positive ion one is the negative ion so now we are only interested in cobalt so i will only pick the cation here so what is the total charge of cobalt is something that we want to figure out so i can write cobalt right here i have one of those
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then there are four ammonia and you know ammonia is a neutral compound so each ammonia is going to be zero plus two chloride ions here so two and each of those carries a negative one charge and all of this added up is going to be equal to zero oh not in this case is going to be equal to
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the charge of the ion which was plus one so now from here we can solve for cobalt so
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this plus one again is coming from the charge of the ion that you see right here so you're going to split your cation and the anion separately and then figure out what is the charge of the complex ion or the metal in the complex ion so for instance in this case this is going to be cobalt
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plus 0 minus 2 is going to be plus 1 so what is cobalt going to be we will add 2 on both the sides that would be this cobalt as plus in this case the charge of cobalt is plus 3 and what is the oxidation state of cobalt plus 3 how many what is the coordination number in this case it is forming one bond each ammonia remember is a uh monodented ligand so each is going to only form one bond with this that is total of four bonds and then there are two chlorine and each chlorine
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can also only form one bond so that is two more bonds which means again the coordination number is in this compound is also six now you'll see for most of the coordination compound the coordination number is six sometimes there's also two and four but most of the times that's six
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so let's try some question give the coordination number and charge of the met central metal ion in the following coordination compound so let's begin with the first one in this case the question is asking what is the coordination number coordination number means how many bonds that's all and what is the charge of the central metal so in this case what is my complex ion i'm going to start with na2 parenthesis znoh for parentheses so to find
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both of these first thing we have to dissociate this so there are two sodium ions so it's going to be one sodium plus for each one of those right and there are two of those which means to neutralize make this compound neutral this complex and which is z and oh four should have a total charge of 2 minus now the question is what is coordination number coordination number is again how many total
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bonds this metal is forming the metal is forming four bonds with four ligands so each of these would make it coordination number of four next is what is the charge of the central metal how do we find the charge again to find the charge i'll put everything equal to the total charge of the ion so zn i only have one of those four times hydroxide each hydroxide is minus one and this total is
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going to be equal to minus two y minus two because the total charge of the ion is two pi so now we are just solving for zn so zn uh negative 4 because it's 4 times negative 1 will give it
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negative 4 is equal to negative 2 so zn is going to be i add 4 on both the side it will be negative 2 plus 4 which means total charge of plus 2. so in this case zinc is carrying a charge of plus 2 and coordination number for zinc here is four
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now let's do the second example so you guys can try this example on your own before i show you the answer so you can pause the video try the question and then come back and look for the answer
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okay so the second compound is potassium with cobalt water and remember c2o4 is an oxalate ligand oxalate ion so you should remember that so if i start with my compound it is potassium in parentheses it's cobalt water holds twice c204 whole twice parentheses so the compound is neutral and what is the complex ion whatever is in the parentheses is the complex amp whatever is outside is the counter ion so if i break this it's going to be potassium ion which is
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a counter ion and i only have one of those and potassium always carries a positive one which means the second ion that i will have will carry in to neutralize this positive charge it has to carry a total charge of negative one so i can break this ion
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as negative one so now i can figure out what is the coordination number what is coordination number remember each water is a monodented ligand so each water is going to form one bond and that makes it two times one and this is coordination number so number of bonds with the metal and then we have oxalate now remember oxalate is a bi dented ligand so one oxalate will form two bonds and i have two of those which means two times two will give me a total of four so that's
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two plus four again the coordination number is the common coordination number which is six now the question is the second question was after coordination remember what is the charge of the central metal so we want to figure out what is the charge of cobalt here so how would we do that again we use this ion right here we total up sum up all the charges and make it equal to the total charge of the ion so cobalt is something we want to figure out plus water what is the total
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charge of water water is a neutral compound i have two of those which means two times zero plus oxalate and i have two of those and each auxiliary if you remember the formula for oxalate ion was i'll write it here c204 two minus so each of them carries a negative two charge and i have two of those so 2 times negative 2 is going to be equal to what oh sorry it's equal to
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the total charge of negative 1 right here so now if i solve for this that means cobalt minus 4 equals minus 1 so now i rearrange this so cobalt will be equal to minus 1 plus 4 which gives it a total charge of plus 3. so that would be the total charge of cobalt in this particular compound
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now let's try uh the last question which is are you h2o2 ammonia chlorine and br so this is just i'm just going over all the components that are present in here for now
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let me clear my screen in the meantime you guys can try this question out pause the video if you have to and then you can come back and check confirm if you have the correct answer okay so let me begin with this part
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so the example we have is parentheses are you h2o2 ammonia two of those oh
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and cl2 and outside parentheses i have br so whatever is inside the parentheses remember that is what is important for me to find the coordination number so now if i'm just solving for coordination number let's just first dissociate it br minus and then i have parentheses r u water
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pole twice ammonia pull twice cl2 this is all that's in parentheses and this if this is negative one this has to be charge of plus one to neutralize that final compound so now what is the coordination number of ru here again we are looking for number of bonds
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so there are two water molecules and each water is a mono dented ligand so it will form one bond then there is ammonia ammonia is also mono dented ligand so each ammonia will form one bond so it's two times one and then there's chlorine and there's two of those and each chlorine also is a monodentate which is going to form one bond so fluorine chlorine bromine you saw the example of fluorine in this slide which means chlorine bromine iodine all of those are halogens as well
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so the total number of bonds that has formed is two to four five six again the coordination number would be six now the next part is the charge of the central metal so again we'll start with the charge of l root so are you we'll say are you
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the next molecule that we have is water and we have two of those in each water is zero why because water is a neutral ligand then i have ammonia two of those in h ammonia is also neutral it has no charge so zero plus chlorine each chlorine again there are two of those but each chlorine is negative one it's a halogen they always have negative one charge and this totals to a total charge of plus one which is written right here so now we
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are just solving for r u r u negative two equals plus one now if i rearrange that it would give me r u equals i add plus two on both the sides that would give me r u s plus three so that would be my total charge of the central metal ion all right
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so that is how you solve questions like this these are fairly simple questions you just have to know the have to understand the idea behind it and this should be fairly simple to complete
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now let's look at the next type of question that you can see here so like i said we have to figure out what is the formula of a coordination compound how would you find out what's the formula of a coordination compound just follow these steps like written right here okay then writing the formula for a coordination compound remember the cation is written first then the it's always cation followed by an i
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then the charge of the cation is or are balanced by the charge of the anion to make the compound neutral so that's always what we do for instance if we make nacl we put one na1c of y because we are trying to neutralize the charge so n a has a plus one charge c a minus has a negative one charge we want to neutralize it that's why you need one of each and exactly what you will do here you do that crisscross approach then the next rule is charge on the complex is the sum of the
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charge on the metal and charges on the ligand so how do you find what is the charge on the complex
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complex ion what we have just been doing so whatever is in the parentheses add the charges of everything and that would give you charge which is right here for the full ion when more than one kind of ligand dispersant this is important when more than one type of ligand is present you always write the neutral ligand first so for instance if i have water and c2o4 2 minus in the same compound water will be written first in the formula so neutral before anionic ligands
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and anionic ligands they both are written in alphabetical order so for instance if i have uh two different types of neutral molecules so i know neutral comes first but which neutral will come first if i have uh water which is aqua and then i have ammonia which is
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nh3 they both are neutral right so which one do i put first you're going to use the alphabetical order in that case so always put neutral followed by charged
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or anionic and then both of those are written in alpha vertical order so if you have two neutrals they'll be in alphabetical order if you have two choice there'll be an alphabetical order and that's it those are the rules but there's also ah look onto those rules later on let's just try a couple examples for instance if i'm writing a compound between cobalt so the question is telling me there is a compound between cobalt two plus there are six water molecules and two chloride
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okay two cl minus and the question would tell you which one is a ligand and which one is a counter ion now you should know what is the ligand and what is the contour and so for instance in this case the question is telling us six water molecules are bound to cobalt ion so these are ligand water is a ligand the two chloride ions are there only to balance the target charge meaning they are counter ions so their counter ions in this case and io
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so we are just going to follow our rules regarding writing the formula so what is the formula we write down the cation first so the two things that we have here is one is a ligand there's cobalt two plus sorry that's calcium cobalt two plus and that is interacting with water right so when you write the formula remember the metal has no choice so i'll write cobalt and then i'll write water and we have six of those so six this would be in parentheses that would be my one ion
43:38
the second ion is cl minus and i have two of those so that's going to be cl2 in minus charge right each of them carries a negative or one charge so that is going to be one of the ions now remember the cation is always written for its this is x and this is minus and i have two chloride ions so now we first have to identify what is x here so how do we find that cobalt is going to be let's
44:05
say we want to figure out the charge of cobalt the cobalt charge is plus 2 we already know that right
44:12
we want to figure out what is x so cobalt is already plus 2. what is the charge of water we have 6 of those each water is 0 which totals up to x which means x is going to be equal to plus 2 or 2 plus which means when i write this formula i can replace this x oh my god
44:34
i can replace this x with 2 plus and then i have 2 cl minus ion neutralizing it which means
44:44
these 2 here and these 2 chlorides are going to cancel each other out so if i write the formula if you write this crisscrossing it so total charge of cl is going to be 2 cl minus right so if you crisscross this that would give you a formula of co h2o 6 times two of these and two of these now remember you cannot have when you write the ionic formula you always put the least ratio that is possible right so if i divide both by 2 that would give me one of this one
45:19
of this and you usually don't write one in the formula which means the formula is going to be just this right here because they will neutralize each other when it comes to the number so that is how you can identify what is the formula for compact
45:35
next let's try one more example here so what is the formula of complex made
45:43
by a g plus n2 cyanide ion so in this case the question is telling us we have wow what is this
45:54
okay so what do we have we have a g plus and two cyanide ions decide if the complex could be isolated as chloride salt or potassium salt write the formula of the appropriate salt so the question is saying there is a g and there is c and minus now you tell me should i put the counter ionus chloride or potassium how can we tell that we'll first write the complex formula for the complex ion there is complex ion so in parenthesis there's a g which is one and then there's cn minus
46:27
right so let's just put this as here ag plus and c and minus so it's telling us there is one a g and there's two c and minus so that is my complex but now i don't know what is the charge when i put these together so i have to now identify what is the charge of my complex ion right so let's identify that so what is a g a g there's only one which means this is plus one oh
46:55
each of them is plus one the question tells us it's a g plus what is cyanide cyanide is cn minus and i have two of those so two times minus one so what is the total charge equal to that is x total charge is equal to whatever the charge of the ion is right so that gives me plus 1 negative 2 is x which is equal to negative 1 which means my formula for complex ion is a g c n whole twice negative one so if this is negative which means what do i have in my formula this is
47:29
going to act as n i n so if i want the formula to neutralize it i need something positive which is i need a cation right and out of chloride and potassium which one is cation chloride is cl minus potassium is k plus i need something positive to neutralize that so my formula would be k is plus 1 and this is a g c n whole twice minus one they are going to cross over and both of them are one so they'll cancel each other out they'll neutralize each other so c n so a g c n
48:09
o
48:12
whole twice and one and one will neutralize each other so that would be our formula for our final compound between a g c n and un counteract so now you should understand this is the complex ion in parentheses this is the counterline just let me neutralize our final compound because it's a compound remember compounds are neutral in charge ions are the ones that carry it right
48:40
okay moving on we have next question so in this case what is the formula for the complex made by copper two plus and four ammonia molecules let's try this questionnaire by ourselves decide if the complex could be isolated as a bromide salt or sodium salt right the formula for appropriate so this is based on the exact same idea what do we have we have hopper two plus so first write the complex ion which is just a copper right comma remember this charges that you see
49:17
they don't go in the formula it's just copper and four ammonia so you just put copper one ammonia as n is three and you have four of those so times four and that's it that is our compound uh complex sign it has a charge now it has a positive negative i don't know i have to identify so i'm just putting an x right here now we'll identify what is x how do we know that copper is plus two
49:46
we know that question tells us this is plus two i have ammonia four of those and i know ammonia has a charge of zero this totals up to x which means this is totaling up to plus 2 so what is the ion that i have i have copper 4 of ammonia and total charge of 2 plus what is the counter ion for this if this is my cation remember cations written first i need an iron so something negative what
50:16
is negative bromine or sodium bromine is the one bromide is the one that is negative so br minus one now to cancel each other and utilize each other out we need
50:54
we need two bromide so the formula would be cu
51:00
nh34 times pr2 now the whole charge of the compound is neutral and that's all
51:11
let's try a couple more example questions the type of questions you can see uh from this chapter what is the oxidation state of iron in the following complex so what is the oxidation state oxidation state essentially means whatever is the oil so whatever is the charge on iron that would be the oxidation state how can i append it by again we'll begin with what we have seen for now
51:34
you don't have to break apart this each time you can just do the whole compound and make it equal to zero because the whole compound is equal to zero right what do i mean by that there are three potassium what is the part of each potassium ion remember potassium is group one it's always plus one i have three of those that's why i have three outside plus iron which is we want to find out plus this cyanide so i have six of those each finite c and minus one
52:03
how do i know that i memorize it okay add all of this up and make it equal to the total compound which is zero you don't see a charge which means it is zero so now i'm just rearranging this to solve for fv so if i rearrange this that would be fe plus 3
52:21
minus 6 is equal to 0 so fe minus 3 equals 0 which means f e equals plus three so that would be my oxidation state or oxidation number or charge of iron in this complex next question is what is the oxidation state of nickel in following complex same idea nickel is what is we want to find out so nickel plus cyanide i have four of those each sine that is negative one total everything up equals to the charge which is outside which is minus two so in this case
52:58
i know nickel minus 4 equals minus 2 to rearrange this i have to add 4 on both this side that would give me minus 2 plus 4 which is plus 2. so nickel would carry a part of plus 2. next question is what is the formula for the complex made by cr 2 plus and 6 ammonium molecules add chlorine or potassium so cr easy if i'm writing the formula i put parentheses there is one cr six ammonia each ammonia is nh3 and each of them is neutral six of those times oh sorry parentheses
53:37
to the power x now i have to figure out what is x cr is plus two i have one of those plus 2 plus ammonia i have 6 of those each ammonia is 0 total adds up to x which is equal to plus 2 so in this case my compound is cr ion times six is two plus and i need a counter line to balance it out so which one do i need something negative something negative here is chlorine or chloride so cl minus one again to balance the charges i need to cross over so that would give me cr nh3
54:14
whole six cl two so this is my formula which is option number c so that would be my final answer
54:28
there you go it shows you all the answers and how we got them
54:33
now let's move on and try a couple more questions what is the formula for the complex between cr and five water molecules and one chloride ion as ligand so it's calling you there is five water and one chloride in all of them is ligand add chloride or potassium ion to form appropriate salt so we have chloride which chromium sorry cr is the metal ion then i have water molecules five of those so
55:03
water times five and then there is one chloride so don't forget that there is one chloride as a ligand meaning this is acting as ligand if it is vegan it's going to be in parentheses and then now i have to figure out what is the charge of this which is x so cr is plus three the question is telling me i have five water each quarter is zero so five times zero plus one chlorine so one times
55:28
each chlorine is negative one equal to x so this totals out to 3 minus 1 which would give me plus 2 so my x is plus 2 which means this is a cation the complex ion is a cation and i need something negative to balance it out which would be negative one so now crossing these over would give me i'm just going to erase it right here and put my final number it would give me
56:03
cl2 i need two chloride to balance out the total charge of plus two over this complex
56:11
now the last part is which the following can act as a chelate vegan remember chelating or chelating ligand is the one which can form multiple bonds either two or more right two or more bonds which one of those ammonia can only do one bond water can only do one bond cyanide can do one bond there is one amine one n can only form one one there are two amines here one and one this can form two bonds which means this can act as a helium that's it
56:48
next we'll move on to the next idea which is how do you name a coordination compound so there are again rules about naming a coordination compound what we saw up until now was how do you write the formula for a compound now we'll see how do we name a chemical compound a coordination compound specifically so again when you name a compound you always write name of catin first followed by n9 how do you remember this you know nacr that's the easiest example this
57:17
is not a coordination compound we know that but it follows the same rule n a is an a plus c l is c l minus we always call it sodium chloride and we do not chlorine chloride sodium right we call it sodium chloride because iron is written first so always cation name goes first then an ion within the complex ion ligands are named in alphabetical order before the metal
57:44
so you first put cation so the first rule is always put ketain name followed by a nine name now you name each of them separately okay how do i name the one of them is going to be complex ion how do you name the complex ion the ligands are named in alphabetical order before the metal so metal comes last legions are named first if it's an anionic ligand meaning something negative drop the ide and add o so for instance if it is cl minus
58:13
what is the name of cl minus it's chloride but when it's a coordination compound you put it as chloro not chloride okay so you remove the ide replace it with the old oh ligands whose name end in ite become ito ligand whose name end in a t e become ato so everything has to end with an o i t e i t o a t e ato okay like nitrite will become nitrite o carbonate will become carbonato okay oxalate is ate will become oxalate that is about naming the ligand now what is the next thing
58:56
a numerical prefix is used to indicate the number of ligands of a particular type so prefixes do not affect the alphabetical order of ligand so remember we put these ligands in
59:08
alphabetical order and the prefix is put before the alphabetical before the ligand name so if i have one of those it's going to be if it's one you don't put any uh prefix if it's two you put this
59:24
if it's three you put tris if it's four you put tetra guess okay you only have to learn till here if it's this tris or tetra case so two three four and now again the base doesn't affect the alphabetical order tris doesn't affect so it doesn't mean if you put a tris in front of a ligand it's going to begin with t that's not the whatever is the name of the vegan that would be the alphabetical order lastly
59:52
a human roman numeral is used to indicate the oxidation state of the metal
59:58
that can have more than one state the name of the metal is written ah and then it's followed by an oxidation state so if it's iron let's say you put a plus three plus two whatever is the charge
1:00:11
and if the complex ion this is when the complex ion is a cathy if the complex ion is an anion we drop the ending of the metal name and add an ate so usually metal name is written as is but if it is an anion you drop the metal name remove the ending and put an ate now let's take a look at a few examples so here are some of the names of the ligand that we saw now remember ligand you think it would be the same name uh that we call them
1:00:46
but that's not correct so for instance please remember this this is something you have to memorize naming you have to memorize how to name them and all these names i do expect you to have them memorized so for instance if it's water it's not called water it's called aqua if it's nh3 it's not called amine it's called a mine a-m-m-i-n-e usually amine is a-m-i-n-e don't make that mistake this is a mean but in in coordination compound it's written as a a-m-m-i-n-e that's how i call it
1:01:21
amine just to remember it then there is co which is carbonyl then there is no which is nitro co these are the uh different kind of names that not so common names that you would see rest everything is very similar and follows the rule that we just saw so you kind of would have to memorize these four carbonyl nitrosyl amine and aqua don't use water okay
1:01:53
next the ligands that are ionic we saw what the name is if it's fluoride f minus is fluoride it changes to ibe changes to o so it becomes fluoro chloride becomes chloro bromide becomes bromo iodide becomes iodo hydroxide becomes hydroxyl cyanide becomes cyano so ib is replaced with o
1:02:16
here are name of some more ligands for instance you have carbonate ate becomes ato so carbonate becomes carbonate this is something this is not something new these are the ligands that you should know the naming of these ligands by now already this is from general chemistry one so you should know their naming by now then there is thiosulfate which is s2o32 minus it's called thiosulfato there is
1:02:43
thiocyanate which is scn minus so it's thiocyanato when the bonded through sulfur it is isothiocyanated when it is bonded to nitrogen i don't expect you to remember each of these uh but definitely remember carbonate oxalate nitrate and nitrite these you should know because you have already known these names and then at least c and minus which is cyanide right so oxalate becomes oxalato then this is nitrite no2 minus no2 minus if it is bonded through oxygen
1:03:19
it becomes nitro if it is bonded to nitrogen it becomes nitro so nitrite ite becomes ito so nitro nitrite becomes nitro it's not ito exactly but it becomes nitro and it becomes nitro if it is bonded through oxygen now what happens name of the metals remember name of some metal iron in complex anion if it is cation if the complex ion is cation the name stays as it is iron is iron copper is copper lead is lead silver silver gold is gold but if they are in anions if
1:03:57
the complex ion is an iron so for instance if this is the cation and my anion is the complex ion okay then your name of the metal will change so iron will become fair weight copper will become tuporate again they add an ate remember we drop the ending of the metal name and add ate so just do that iron is fed ray by ferrous so it becomes very copper becomes cube rate lead becomes plummet
1:04:30
silver becomes arginate gold becomes orate tin becomes denate aluminum becomes aluminate manganese becomes manganate nickel nicholate zinc zincate platinum platinate vanadium vanadate cobalt cobaltate so most of those are very similar the weird ones or something different is essentially here lead is plummet silver is arginate gold is orate thin is standard rest everything is same and also copper is cube rate not copperate
1:05:02
it's cube rate iron is not ironate it's period okay so these are the ones that you kind of will have to spend some time on but otherwise rest is you just add an ate at the end
1:05:18
oops i should
1:05:25
some of these so for instance this is an anion okay first thing you have to identify the complex ion is cation or an ion complex ion is anion so what is the rule i put the ligand name first ligand is cyano it's cyanide right so it becomes cyano cyano and how many do i have i have two of those so that becomes di cyano and silver silver is if it is cation here this is anionic in nature which means it will be origin a this is where the name of the metal changes now remember it said
1:06:01
always follow the metal name with the oxidation number so i have to find oxidation number of silver here how do i do that again i'll assume silver is silver each cyanide carries a total charge of negative one which totals up to a total charge of negative one because of this negative 1 so silver minus 2 equal minus 1 which means silver equal plus 1 so this is going to be 1 and since this is an ion it ends with iron if it was a compound you don't put anything for instance if
1:06:36
i'm naming n a plus right remember always go back to this example of sodium chloride if i'm naming any plus i don't call it sodium sodium is any what is n a plus n a plus is sodium ion similarly you call this ion because this is an ion it has a charge to it okay so just don't leave it at that
1:06:56
let's look at the next one okay i'm the answers are showing here but try to not see the answers and try to name them yourself so what do we have here this is again an anion which means the name of the metal is going to change first thing next thing is you always name the ligand forest so what is the ligand in alphabetical order i only have one i have hydrox hydroxide remember ide becomes o so hydroxide becomes hydroxyl so how many of those do i have prefix would be tetra hydroxo
1:07:36
and see there's no space anywhere it's all connected and so don't put any spaces anywhere
1:07:44
hydroxyl and now the name of the metal which is zinc but since it's in an iron it will become
1:07:52
zincate followed by the chart ion now let's find the charge it's going to be zinc
1:08:01
let's assume that is zinc four hydroxide so
1:08:07
each hydroxide is
1:08:11
plus one so zinc plus oh zinc plus four hydroxide is each is minus one total minus two
1:08:22
so that means zinc minus 4 equal minus 2 so zinc will be plus 2. so in this case it will be zinc 82 so don't forget any of these steps because this is all credit or no credit so it's going to be legal name followed by prefix legal name followed by the metal name
1:08:46
the next example is right here so what do i have here i have cobalt ammonia six ammonia ligands this is a ligand and this is cationic in it which means the metal name is going to stay as it is what is ammonia called first let's by the name of the anion which is a mine how many of this do i have six which means it's hexa now if i put hexa photo it's going to make it double a so you just put one a in between okay take off one of those is you don't put double a's so hexa amine
1:09:22
cobalt because this is a normal and a cation so it's going to stay as it is and now i put metal followed by charge ion so let's find what is the charge of this metal cobalt is cobalt plus six of ammonia ammonia is zero the total charge is equal to plus three which means cobalt is plus three so i'll put a 3 right here in roman numerals don't put 1 2 3 it has to be always roman numerals
1:09:55
lastly i have this this is going to be a little tricky one so remember e en en is ethylene diamine you have to know its name ethylene diamine i don't expect you to know the symbol or the structure but just have an idea if you have two amines and two carbons that is a clean diamine and again this is a whole compound so now it's not an ion this is a complete compound so what do you do you first name your cation then your anion what is the name of the cantilean that is
1:10:26
an ion so i'll have to name it separately what is the name of the anion chloride that never changes right nacl sodium chloride so this is the name of the anion chloride this is outside the uh complex ion so we don't make it chloro it stays as chloride whatever is inside that naming changes so let's name this we'll first put name of the ligand which is ethylene diamine how many three which means it's tris ethylene
1:11:02
diamine followed by name of the metal which again in this case is cationic in nature so it's going to be same manganese followed by charge and then followed by the final ion which is chloride so now to find this parentheses how do i find that again mn you don't have to separate it out you can just start with this mn
1:11:28
three ethylene diamine and if you remember each ethylene diamine is
1:11:33
neutral so the total charge is zero plus two chloride which is two minus one and total charge is equal to zero because the total charge here is zero so m n minus two equals zero meaning m n equals plus two so the total charge here is going to be plus 2 that is the name of this compound
1:11:59
now next question is what is the correct name of nibrcn ammonia three okay how would we identify what is the correct name now you have multiple negans in here it's a neutral compound there are multiple negan's here so now we have to name them by alphabetical order so let's name it nickel will stay as nickel this will come at the end it's a metal right so i have bromo
1:12:28
i have cyano and then i have a um mine which is alphabetically correct a mind comes first then bromo then sayono how many are mine two so it's going to be
1:12:49
of mind right so let's see if we can find a name there's no base but there's a dye
1:12:57
a mind okay so we can work with that dye our mind bromo cyano nickel 2 now we have to figure out if it's actually nickel 2 how can we do that nickel let's assume it's nickel br is 1 and there's
1:13:14
negative 1 always in br so 1 times negative 1 cyanide is also one so i have one times negative one and ammonia is neutral so it's zero equal zero y because total charge is zero so nickel minus one
1:13:31
minus one equal zero so nickel minus two equals zero so nickel is plus two so that is correct i'm thinking the correct answer is b which is diamine bromocyano
1:13:48
okay now let's predict the formula for these we have one formula before again formula is also from benign but now we have to do from the naming formula so how can we name it it's very simple formula through uh name two formula is very easy what do you see tetracyanus so let's pick each of these so tetracyano means i have cn o4 then it's cuberate so i have copper and it's cuber rate right which it's not copper cubed it means the total ion charge is going to
1:14:22
be negative because it's an anion and it is copper plus one right so what would be the formula copper followed by 4cn and that's it now i have to find the point of this ion so cn copper is plus 1 plus each of cyanide is negative 1 so total charge is equal to x which comes out to be a total charge of negative 3 so my actual formula is going to be replace x with 3 minus
1:14:54
right so now let's move on to the next one which is try
1:15:02
a mine so put each of them separately okay
1:15:06
nh3 i have three of those thio cyano thio was s c n and there's only one of those because there's nothing no prefix before it and then there's platinum and platinum is plus three so we have to make a compound between these three so how would we make that you write three platinum first
1:15:32
oh sorry don't look at the answer yet so we'll write the uh in parentheses it's going to be platinum first followed by the iron which was amine and scn now remember we always put the uh
1:15:50
neutral league in first so this is partially not correct you should put the neutral ligand first so what is going to come first is ammonia which is the amine followed by scn which is a negatively charged one and now we put the total charge x and what is x you'll find that because platinum is plus 3 given to us in question three are mine which is three times zero once higher sine which is negative one is totally
1:16:16
equal to x so three minus one means plus 2 is x so x is plus 2 so this x i can replace it with
1:16:26
plus 2. so don't leave it as x okay make sure you give me the final answer so this is your final answer lastly we have potassium so potassium is going to be plus one remember this is this this is no longer has an ion next to it which means this is a compound so i see cation name is always written first so potassium is methyl
1:16:51
i have cn six of those ferret means fe and why is it called ferret because the total complex ion is going to have a negative choice i don't know how much so i'm just going to leave it as negative x for now we don't have to find we'll have to find it eventually ferret is plus 3 so let's figure out what is the charge of this x ion if we want the final formula we need this right so six times cyanide each cyanide is minus one plus iron i n it's telling us is three
1:17:24
equal to x so forget about this minus sign for now i know it's minus y because if it was a plus or a cation it would be iron because it's not it i know it's 9. so this is going to be equal to x between minus 6 plus 3 is equal to x so x is equal to minus 3 so now how do i write the final formula it's potassium first put the metal fe cn 6 minus 3 so now we cross over the charges to balance it out
1:17:59
to balance this charge of minus three i need three potassium f e c n sorry c n six so that would be a final answer for this so you just make sure you cross over the charges to balance it out
1:18:17
and that's all
1:18:21
so there are a few more examples which you guys can try on your own what is the systemic name of this what is this systemic name of this what is the formula of this what is the formula of this so essentially the kind of questions you'll get from here is either naming the formula uh writing the formula from the name or naming the compound if the formula is given to you so make sure you understand and remember the naming rules and remember the rules for writing the formula
1:18:52
and those are the major questions that will come from this part of a chapter there's this last chapter part which i'll cover in the last video which talks about different forms of isomers of coordination compounds along with isomers we'll talk about a little bit about uh
1:19:10
distribution of electrons uh crystal field here i am not going to give you much questions from there but yes isomers uh you should definitely understand what are isomers so we'll talk about isomers in the next video
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