In this video, we're gonna talk about the ligand types. Now ligands themselves represent molecules or ions that act as Lewis bases, and donate at least one lone pair to a metal cation. Remember, a Lewis base is an electron pair donor, The metal cation will behave as a Lewis acid and accept that lone pair. When we talk about ligand types though, we're talking about neutral ones versus negatively charged ones or andionic ones. Now cationic or cationic like ligands, those with positive charges do exist, but we don't talk about those types within Gen Chem. So for right now, just realize that the ligands that we're gonna observe are either gonna be neutral or negatively charged. If we take a look here, for our neutral ones, we have ammonia. It's a ligand because we have this lone pair which we could donate to a metal cation if we chose. Water, we could donate one of these. Here we have carbon monoxide here. In the structure overall, it is neutral. But if you were to do the formal charges of the carbon and the oxygen, carbon will be negative, oxygen will be positive. And it's the negatively charged n that would be donating its lone pair. Also remember that carbon ideally wants to make 4 bonds. So out of the 2, it's the one that wants to make a bond. It's only making 3 here. O 2, both of those oxygens are the same. Either one could donate a lone pair to our metal cation. On the other side, we have our anionic ligands or ligands, those that have negative charge. So we have hydroxide ion, we have x minus, remember x represents a halogen, those in group 7 a, so it could be fluorine, chlorine, bromine, or iodine. We have our cyanide ion, again the negative charges on the carbon here, so it's what will donate its lone pair. Then we have here a thiocyanate ion. In this case, we have lone pairs in terms of this. We could have the formal charge of negative on the nitrogen, so it could donate its lone pairs it chooses to to our metal cation. So for right now, remember, ligands or ligands represent Lewis bases where they can donate a lone pair. We can have them either be neutral or them be negatively charged. In either case, they will donate a lone pair to a metal cation.
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example
Ligands Example
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Here it says, which of the following would represent a neutral ligand or ligand? So here we have bromide, hydrogen sulfide, ammonium ion, hydroxide ion, and cyanide ion. First of all, remember, we said that the ligand types that we will focus on in Gen Chem are either neutral or negatively charged. Ammonium ion is positive, so it's going to be out. Next, we have bromide. I means it has a negative charge, minus 1. So that's out. Hydroxide, Ide again, negative charge, that's out. Cyanide, c n minus, that's out. The answer is b here. Hydrogen sulfide represents h two s. H two s is similar to H2 o. Remember, h two o we saw as a common type of neutral ligand ligand, so hydrogen sulfide will fit the same bill. So after we're substituting out the oxygen for a sulfur, it'll be given the same way. So in this case, option b represents our neutral form of a ligand.
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concept
Ligand Reaction
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Now a ligand reaction kinda coincides with something we've seen before. Recall that the adduct equals the product of a Lewis base and acid reaction. So remember, a ligand or ligand represents a Lewis base, it's donating a lone pair to a metal cation, which represents our Lewis acid. Now when we talk about, adduct, we're adding them together, the overall charge of an adduct equals the sum of the metal cation plus ligand or ligand charge. So if we take a look here, we have our metal cation in the form of cadmium ion. We have our ligands, which is water. Here, this is a metal cation which can accept the lone pair, so it represents our Lewis acid. And we're gonna say here that water can use one of its lone pairs and donate it to that metal cation, so this is our Lewis base. Now it could be multiple waters attaching to this cadmium, not just necessarily one. Here we have our adduct. We have in fact 4 water molecules attaching themselves to 1 cadmium ion. So here, because it's an ion, we put it in brackets, and the charge is gonna be on the outside. Cadmium has a 2 plus charge. The full water molecules that we're adding to it are all neutral, so their charge is 0. So the overall charge would be the charge of the metal cation plus the charges of the ligands. So overall, that's gonna be 2 plus. So this would be the overall charge of our adduct product between our cadmium ion and 4 water molecules.
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example
Ligands Example
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Determine the adduct product when a nickel 3 ion combines with 2 bromide ions. Alright. So we have nickel 3 plus, and it's gonna combine with 2 bromide ions. It's going to be ionic in nature, so we have the plus 3 from the nickel. Each bromide ion is minus 1 and there's 2 of them, so that's minus 2. We'd have left over for our overall charge a plus 1. So here this adduct has a charge, and because of that we have to place it within brackets. So this represents our adduct product.
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Problem
Problem
Determine the charge of the metal cation in the given adduct product below:
A
+1
B
0
C
–2
D
+3
E
+2
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Problem
Problem
Determine the type of ligand connected to the calcium ion.
A
Neutral
B
Anionic
C
Cationic
D
Not enough information given.
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Problem
Problem
Determine the overall charge of the adduct when the aluminum ion combines with 2 bromides and 1 chlorides.