Oxidation States of D-Block Elements | Cengage Chemistry | Dr. Balraju Karri | JEE & NEET

[00:00:02]Good morning everybody. So after understanding the wonderful oxidation states in the p block, let's talk in this video about what things are related to oxidation in the d block? We will talk about that. So one thing we studied from the d block in the p block is what is the down group stability of higher oxidation state? Decreases.

[00:00:22]Meaning the higher oxidation state of the above elements is stable. And stability of lower oxidation state increases down the group. And if you are asked question Y in the exam then say int pair effect. In D Block, it is not exactly the opposite. In D Block it is exactly opposite to the P Block. The stability of higher oxidation state increases down the group. Increase down the group. This is the first exception. Isn't it?

[00:00:50]Stability of higher oxidation state increases down the group. And what is the best example to prove this? Like we take the chromium group. Let us take Chromium Group that is Chromoton is not Chromaton company is not fan's. So chromoton this is tungsten so chromoton this is chromium mallb tungsten. If we take these three compounds, then here chromium forms K2 Cr2O7 where it shows +6 oxidation state.

[00:01:20]That is the higher oxidation state of this group. And molds shown in the figure form InO3 and WO3.

[00:01:26]These also show +6 and +6 oxidation states here. Now K2Cr2O7 we all know is one of the best oxidizing agent. We use it in organic chemistry.

[00:01:36]Right? But MO3 and WO3 they are not very good oxidising agents.

[00:01:45]They are not good oxidizing agents.

[00:01:49]Whereas this is the powerful best, we will call it the best oxidizing agent. This is the best oxidizing agent. All three of you are in +6 +6 +6 state. So these two are not behaving. So if you have watched the P Block video carefully then let me repeat it again. Look, if someone is in a stable oxidation state, if he is stable then he will react or not. Those who are stable react. Not there. He said, brother, I am happy here. We neither have to decrease nor increase the oxidation state.

[00:02:21]Who will do it? If we are talking about the best oxidizing agent. Meaning that it is very reactive. It is reactive meaning that +6 is not stable. So +6 is the higher oxidation state. So chromium's +6, theirs is also +6, these are not reacting at all.

[00:02:37]They are not oxidizing agents.

[00:02:39]How does that mean their +6? Their +6 is stable.

[00:02:43]How is their +6? It is stable. That's why he is not reacting. Their +6 is unstable. That's why he is reacting. So down the group stability of higher oxidation state is increasing. It is unstable above and stable below. So what's happening here is the stability of the higher oxidation state down the group? It is increasing. This is the first point. You should know it. The second point we need to know within the D block is which shows the highest oxidation state? The highest in the entire d block is osmium.

[00:03:15]How much does it show? It can show +8 in its compound called as osmium tetraoxide.

[00:03:23]Osmium shows +8 oxidation state in osmium tetraoxide.

[00:03:29][laughter] Manganese also shows +7. Right? But the 3D series has the highest manganese. Because the highest within the 3D series is +7. But osmium has the highest oxidation state in the entire periodic table. You should remember this second point.

[00:03:44]Third point. Well, who helps them in showing this higher oxidation state? Who helps them show higher oxidation state. Those would be the most electronegative elements. And who is he? Fluorine and oxygen.

[00:04:00]Fluorine oxygen helps them exhibit higher oxidation states.

[00:04:07]But the question will be this, come on brother, both of them will help in showing the higher oxidation state.

[00:04:13]But which one is better?

[00:04:16]Once we see Floren's point.

[00:04:17]Florin, which is not what we have? Scotty VCR Manganese even talk.

[00:04:26][sound of clearing throat] Titanium will form TiF4 from fluorine and show +4.

[00:04:33]Vanadium will form VF5 and show +5.

[00:04:37]Its higher oxidation state. Chromium will form CRF6. +6 will show. Higher oxidation state. But what is the higher price of manganese?

[00:04:47]Is +7. Fluorine cannot form Mn F7 with manganese.

[00:04:53]You have to remember this is an exception.

[00:04:58][laughter] All of these are formed with fluorine in its higher oxidation state, and all of these are formed with oxygen as well. TI can show TiO2 vanadium pentoxide here +4 here +5 and this is CRO3 +6 means to show higher oxidation state of titanium vanadium chromium both are equally powerful. Fluorine can also show oxygen as well. When it's Manganese's turn, Mnf7 is not possible. But U can form +7 bola oxide.

[00:05:35]Which oxide does it form?

[00:05:37]Mn2O7 and Mn2O7 is what I made?

[00:05:48]Green It's a green covalent oil. Remember the question is made in it is it a green covent oil.

[00:05:58]So what does manganese do when it has to show +7 to fluorine? This fluorine takes the help of oxygen. It takes help of oxygen. It forms MnO3F.

[00:06:11]This is a compound of fluorine. From manganese where manganese shows +7. But here it is not just fluorine, oxygen also helps here. So tell me, after seeing all this, what will you do?

[00:06:23]Which is better fluorine or oxygen?

[00:06:25]Put it in the comment box. Who is better?

[00:06:27]How many votes does Floren have? How many votes of oxygen? Everyone thinks fluorine would be better. Because fluorine is the most electronegative element. That's why everyone thinks fluorine must be better. But it is not so.

[00:06:40]Oxygen is better. Because oxygen can help with manganese and its highest oxidation of each element. Now suppose I gave you the example of osmium. If you tell Osmium Bhai Saheb to combine with Fluoren and show the placenta, then Osmium will have to form a bond with eight Fluors and such a molecule does not exist. You know what geometry highest geometry is?

[00:07:04]Pentagonal bipyramidal. Such stable geometry is maximum only up to octahedral.

[00:07:09]But if you go above that, you will see some pentagonal bipyramidal molecules. It is not above him at all. This means that a maximum of seven bonds are possible. Here it is not at all possible to make eight bonds.

[00:07:22]But the same osmium forms bonds with oxygen very simply. Four oxygen is enough. Why? The Reason Is Oxygen Can Form The Pi Bonds. You know that if a bond has to be made with oxygen then it will easily form a pi bond. Oxygen forms double bonds. Forms multiple bonds.

[00:07:39]What does that same fluorine do?

[00:07:41]Forms single bonds. So that's why it's taking eight fluorines here for plus eight.

[00:07:46]Four oxygen is enough here. Because one oxygen will form two bonds. This ability of oxygen to form multiple bonds makes it better than fluorine to help this element exhibit their higher oxidation states. So this also raises the question why what?

[00:08:03]Right? You are clear with that. So these are the questions in D block where oxidation state based questions are important. Let's add one more thing. D block elements show variable oxidation states.

[00:08:16]And this is because they can show variable oxidation states that act as good catalysts. Here the question can arise whether they are good catalyst assertions. What is Reason?

[00:08:25]Because they can show variable oxidation states.

[00:08:27]What exception comes for this? The exception to this is scandium. Scandium shows only one oxidation state. +3 oxidation state. It does n't show anything else. So if we talk about it this way, then scandium should not be a transition metal. But why did it happen? So the definition of transition metal is it must have at least one unpaired electron. So scandium has a D1 configuration so it survived.

[00:08:51]Otherwise, you will find more properties of transition metals in it.

[00:08:55]No, just missed. Isn't it? Because it shows the operation state of only one variety.

[00:09:00]So sometimes people say scandium should n't be here. But then because of unpaired electron definition is following. So we placed scandium there. Right? So these are different you know concepts on which question comes in d block on the basis of oxidation state.

[00:09:18]If you are asked what is its common oxidation state? So the common oxidation state is +2 and +3 within the d block.

[00:09:24]You all know this. So infection. If this is asked about the lowest common oxidation state. You have to read the question carefully. Okay, right? The lowest common oxidation state is +2. And it has just been said that what is the common oxidation state? And you have to tick only one, so +3. If you have given multiple correct answers and this is an advanced question, then tick +2 as well as +3.

[00:09:46]Thank you very much.

[00:09:48]In the next video we will talk about F Block.

[00:09:50]Inside the F block are small things that can come up with Occupation State based questions. We will discuss. And apart from this, if you want to know or understand any other topic, then please put it in the comment box. Thank you.