NECO CHEMISTRY THEORY 2026 REVISION CLASS

[00:00:00]Yes, you welcome everyone to iMac and today we'll be looking at the NECO chemistry theory 2026 revision class. And here in the class we've got some questions to attend to and let's see them one after the other. Okay, now the very first question here says what is fermentation reaction?

[00:00:21]What is fermentation reaction? Of course, fermentation reaction is peculiar to glucose. So we simply say that it is it is a slow decomposition reaction okay, in which glucose >> [snorts] >> all right, in the presence in the presence of an enzymes okay, known as zymase.

[00:00:59]All right, is converted is converted to ethanol ethanol and carbon four oxide.

[00:01:11]Carbon four oxide, okay, that's exactly what fermentation is. It's peculiar to glucose alone. All right, now the next question here quite familiar to fermentation reaction tells us or is asking us rather. Now with chemical equation only show ethanol can be formed from starch.

[00:01:33]Exactly as we have defined in the fermentation just before now. All right, now remember that glucose as we said is the primary product from starch. Okay, the starch if broken down okay, into the smallest unit we have what we call the glucose. Then before the glucose is fermented to ethanol and carbon four oxide. So in other words, here it actually means that we should originate from starch, okay, showing how the starch degrades firstly or is hydrolyzed, as the case may be, to maltose, a disaccharide, and further how the maltose is hydrolyzed further to glucose. Then we proceed with fermentation, okay? Then exactly it gets us. So, let's begin with the starch. Of course, we know that starch is an isomer of glucose. We have C6H10O5, okay, in the presence of water.

[00:02:30]Now, we call this reaction hydrolysis.

[00:02:33]Now, we have a large macromolecules broken down in the presence of water is called hydrolysis.

[00:02:39]We've got that to produce uh what we call a disaccharide, that's C C12 H okay, that is 22, then O11, all in the presence of water again, okay? We've got this alone to be this alone to be maltose. Now, got the sugar to be maltose. Then we need to further the reaction, that is maltose would then be broken further into a a a mono- a monosaccharide, rather, that is called the glucose, okay, in the presence of water called the hydrolysis. We call this hydrolysis. And the enzymes responsible for this Now, let's be detailed here. The enzyme responsible for the hydrolysis is called a diastase.

[00:03:25]Okay, diastase. Diastase is an enzyme that is peculiar on acting on cooked starch or starch to break it further into maltose. As a matter of fact, diastase simply means any group of enzymes being able to change starch to maltose, okay? So, now, we've got that level there, diastase. Now, diastase, we've got the immediate product here to be maltose. Then maltose is further broken down. So, let me get the maltose here again. That is C12H22O11 in the presence of water as well, which we refer to as hydrolysis again. Okay, hydrolysis. This very time because the substrate is maltose. Therefore, the enzyme here is maltase.

[00:04:15]We've got it to be maltase. All right?

[00:04:17]Then it breaks it down to glucose. Being a simple sugar this very time. C6H12O6.

[00:04:24]All right? Then this is the smallest unit of glucose to be obtained from the starch. Then after which the starch the glucose undergoes fermentation here.

[00:04:33]Then we have ethanol produced. Okay? The glucose C6H12O6.

[00:04:41]Okay? In the presence of an enzyme called the zymase.

[00:04:45]It is converted to ethanol C2H5OH and okay, carbon four oxide. So, we've got this reaction to be obtained from the series of processes involved in starch converted to ethanol. All right?

[00:05:02]So, we've been able to answer that. We proceed to the very next question. The next question says, "How many moles are contained in 25 g of magnesium trioxocarbonate four?"

[00:05:15]And let me get that again. How many moles? Here notice, we're not specific the element in question.

[00:05:21]Perhaps they mean the whole of the compound. I suspect. How many moles are contained in 25 g? All right. So, the first thing we need to get do is Now, let me analyze that into the formula.

[00:05:33]The molecular formula of that we've got that to be magnesium trioxocarbonate four. Okay? We've got the compound to be MgCO3. Now here, it is very expedient that we get correctly the molecular formula as in an attempt to get the molecular formula wrongly, automatically makes us get the answers to solve wrongly. All right. So, being able to do that, okay, as this compound here, we are to simply find how many moles of the magnesium trioxocarbonate (IV) can we have in 25 g of the same salt? In other words, we are to convert 25 g to mole.

[00:06:09]And you recall this.

[00:06:11]You know, recall this.

[00:06:13]Recall that number of moles Number of moles is always given as given mass over the molar mass, meaning that if you are to convert mass to mole or mole to mass, we've got this formula to be the way out. All right. So, here we're given the mass. We've been asked to convert to mole. Okay? So, 25 g serves as the given mass, while we need to compute firstly what we call the molar mass of the salt. Now, here we're given the relative atomic masses.

[00:06:42]Magnesium was given as 24. So, got 24 plus carbon here is given here as 12, okay? Then oxygen, one atom of oxygen is 16, and here we've got three atoms of it. So, 3 * 16, we've got that to be 48.

[00:07:00]So, adding all of this together, we've got this to be 60.

[00:07:04]Okay? 60, then 84.

[00:07:08]Okay? 84 g per mole. All right? Perhaps I work with the uh to avoid any unnecessary error. Okay? Here. Now, let me have that again. Uh 16 times three.

[00:07:25]Okay? Add that with 24 and 12. We've got everything to be 84 g per mole. Then, now we proceed to the formula by saying the given mass in the question, 25 g, over the molar mass just computed to be 84. So, you've got to divide 25 by 84. Okay, now let's get that done. 25 / 84. So, we've got that to be the number of moles we've got in that mass is now 0.29 Okay, moles.

[00:08:02]Okay, 0.29 moles. We've got that moles to be exactly in 25 g of the magnesium trioxocarbonate (IV). So, we move on to the next question, all right?

[00:08:14]Now, here Here, we're given two halogens and we are asked to complete the table here, okay, in this form.

[00:08:24]Okay.

[00:08:27]So, state the states of the respective halogens at room temperature and their respective uses. Okay, as their respective uses also. All right, so here, let's begin with this. Now, it is important to know that all halogens, being group seven elements, they are all gaseous. Okay, all right, they are all gaseous at room temperature. So, we can conclude that fluorine is a gas at room temperature. Chlorine also is a gas at room temperature.

[00:08:57]Though they can exist as other form, but at normal temperature, almost so to say, okay, naturally, they exist as gaseous.

[00:09:05]That's what we mean by room temperature.

[00:09:07]All right, so their uses. Fluorine has several uses. Anyway, fluorine can be used in in you know, in dental health, all right, to prevent cavities and to to to protect our teeth enamels. Okay, so here, I can also use fluorine in producing a very very durable due to its uh stability and unreactivity. We use it to produce a very durable plastic, okay, or a polymer known as a Teflon.

[00:09:36]Okay, it's a very durable polymer, okay?

[00:09:39]We will use fluorine to produce due to the stability of the fluorine. Now, chlorine also can also be used in several ways, among which includes uh it can be used as an antiseptic due to the oxidizing nature of the atom or the bleaching tendency of the atom. So, I can also use for an antiseptic, okay? That's it. against microorganisms.

[00:10:07]So, I've been able to attend that question. The next question says, "Name a suitable indicator for the titration of a strong acid against a weak base."

[00:10:17]Quite interesting and just tell. Now, here we've got to Now, let me narrow it down. We've got several uh you know, indicators, but in this context, and let me write it down. We have the litmus paper. We've got the methyl orange and of course we've got the phenolphthalein. Now, the methyl orange and the phenolphthalein, they are used in different scenarios. Methyl orange is better used when we have a strong acid, as we have in this case, against a weak base. While phenolphthalein is used in the, you know, in the other way. That is, when we have a weak acid and a strong base. Why all of this? Now, the reason is this. Methyl orange, of course, now let me bring us down. If you have a react a strong acid with a weak base, it's either It's just like saying to layman that when you have a a strong gene, you know, um Y chromosome in man, and a strong gene and a weak X chromosome in woman, then you will definitely have the child to look like the father because the gene of the father seems to be dominant.

[00:11:27]So, therefore, in this case, where you have a strong acid and a weak base, expect the salt to be to tend towards acidic salt. And what does that mean?

[00:11:36]And at the when the salt is formed, it is called the end point. Okay, the point of equivalence. Now, what do we mean?

[00:11:44]And so here, when we have the salt formed, the salt formed tends towards being acidic. That is, having a pH lower than seven.

[00:11:53]And methyl orange, as the case may be, okay, will show a very sharp color change. You know, it will indicate a very perfect color change with with within within the range of the pH of 3.1 and 6.2.

[00:12:09]Okay, phenolphthalein is best from 7.9 to okay, 10.3.

[00:12:16]Now, notice this. Methyl orange has a very clear color indication between this range. This range here indicates acidity. This range here indicates basicity. And so, you're likely to have a more accurate, you know, change color indication with methyl orange in acidic So, in that case, when you know that the salt formed will tend towards acidic, then methyl orange, which will show a perfect color indication, will be better for such reaction. Okay? But in the other way, phenolphthalein will be better. Phenolphthalein shows a better color change, okay, in or a perfect color change in a basic medium. That's why phenolphthalein would rather be used when you have a strong base and a weak acid. Why? Because the salt that will be formed afterward will tend towards being basic. And so, phenolphthalein will indicate that perfectly. So, that's the point. So, in this case where we've got a strong acid and a weak base, okay, we have no other but the methyl orange to be a perfect indicator for that. So, move on to the next question. Now, give an example of acidic oxide, neutral oxide. Now, what are acidic oxide?

[00:13:34]Acidic oxides are oxides of nonmetals, okay, which when dissolves in water may produce a weak acid, okay? And we've got acidic oxide to be the likes of Okay, carbon four oxide as an acidic oxide, okay? All right, sulfur four oxide is an acidic oxide. And also we could have sulfur six oxide being acidic oxide. Sulfur six oxide, okay? Sulfur four oxide, carbon four oxide. We may have any of these. We are to give an example, so we may pick any of those examples from there. Now, the next one, neutral oxide. Neutral oxide, very most common neutral oxide, okay, is water.

[00:14:18]This is a neutral compound, okay, that is most abundant in nature. Anyway, now we've got another neutral oxide to be, okay, nitrogen two oxide, nitrogen two oxide. And also we've got dinitrogen one oxide, dinitrogen one oxide, which we refer to also as a laughing gas, okay? Now, we could pick any of these. I can also give this an incomplete, you know, um oxide of this.

[00:14:48]Carbon monoxide. Any of these can actually stand in for a neutral oxide.

[00:14:55]Now, not to waste our time further, question here says, "Give one difference between hydrophobic and hydrophilic."

[00:15:04]The word hydro here connotes water molecules.

[00:15:09]Hydro, water. The word philic here means loving.

[00:15:14]The word phobic here means not loving, okay? Has a phobia.

[00:15:20]Now, to have phobia means to have fear for.

[00:15:24]Okay? So, when I say hydrophobic, it means not water loving here. We mean water We mean substance here that do not that are not compatible with water. But here, we mean substance that are compatible rather with water. So, I can proceed. We have to give one difference anyway. So, permit me to give two. Okay? All right, here.

[00:15:44]Now, let me have hydro- -philic here, and of course here, hydrophobic.

[00:15:52]Okay? Hydrophilic, we said they are They are Okay?

[00:15:59]Water loving.

[00:16:01]Okay? Here.

[00:16:04]They are not water loving.

[00:16:10]Okay? All right. Now, somebody else may use another word. They are compatible with water, or they are soluble in water, so to say. And here, they are not soluble, or they are not compatible with water. However, you may express it. I've just decided to do it this way. They are water loving. They are not water loving.

[00:16:30]Okay? Number two. How else can I explain that? Now, because this is not water loving, means that they could be They could be soluble in organic solvent. In a solvent such as oil, I can say they are soluble.

[00:16:47]Okay?

[00:16:49]In oil.

[00:16:51]Okay?

[00:16:52]They are not soluble.

[00:17:01]No, no. I think I took it the other way around. Here, they are not soluble.

[00:17:06]Since they are not water They are water loving. And so, they are They are polar solvent. Okay, I can even use that. I can say, since they are water loving, they are polar substance.

[00:17:23]Okay, here I can also go in that format.

[00:17:26]They are nonpolar.

[00:17:31]Okay, substance.

[00:17:33]They are nonpolar substance, all right?

[00:17:36]Now, somebody may decide to work in the other one I was trying to put there, okay, as being uh not soluble in oil, soluble in oil.

[00:17:45]However, the number, but here we are to just give a difference, just one. Now, we move on to the next one. Write the IUPAC nomenclature of the following compounds here.

[00:17:54]Now, I've always told students, this is another question that are very, very direct and interesting. All you need to do is just get used to the functional group. Now, identify the functional group here as this and here also as this. Now, once you are able to get the functional group out of it, then you name it exactly as the name, such that the old name ends with uh the suffix of that functional group.

[00:18:20]Here, the functional group here is we've got it to be uh an alkanoic acid, alkanoic acid. So, we are to end this name with -oic, however. Now, let's get the the chains, the carbon chains we've got there. The carbon chains. We've got this carbon, one.

[00:18:37]This carbon, so this carbon in the functional group included as three.

[00:18:43]Now, under normal circumstance, we've got the first member to be methane.

[00:18:48]In the corresponding alkane homologous series, the next is always what? Ethane.

[00:18:54]Okay, the next one is what? Propane.

[00:18:57]The next one is what? Butane.

[00:19:00]Okay, the next one is what? Pentane. The next one is what? Hexane. The next, heptane, octane, nonane, decane, undecane, dodecane, and the likes of that. So, that Now, here, now since we've got three carbon here, 1 2 3, and the top here labeled here was propane.

[00:19:18]And so, we've got the name to be here as pro propane, but it should end with oic, propanoic acid.

[00:19:29]Okay? How Why is the oic acid? Due to the functional group. Why the propane?

[00:19:36]Because of the three carbon atom here.

[00:19:37]So, we've got the name propanoic acid from that. Now, we'll go to the next one here. Now, notice that we do not have a carbon atom in the functional group here. The functional group here alone stands for the homologous series for that of alkanol.

[00:19:52]Okay? Alkanol having a functional group of OH. Now, let's get counted the carbon atom the carbon. 1 2 3 4. We've got four carbon atom, and based on the number I gave here, the methane, the ethane, the propane, the butane, four. 1 2 3 4. So, we've got four, that should be bu. Then, being ol, we've got that to be bu ta nol. Not that I'll say this every time.

[00:20:19]So, we've been able to name this, name this, then proceed to the next question here. Now, the next question here we are to do Uh here, we are given the formula, the molecular to name it. Here, we are given the name to give the structure. So, here, write the structure of the following, hydroxylbenzene.

[00:20:36]Now, firstly, these are derivatives.

[00:20:40]Okay? And of course, this also, they are derivatives of benzene. Now, to go about it, just get the benzene structure firstly. Okay? Benzene structure.

[00:20:50]Okay? This very way. Okay? Benzene is got six Benzene is got six carbon chain. 1 Okay, let me hold this. 1 2 3 4 5 6. It is then an aromatic hydrocarbon. Okay? All right. Double bond here. Okay? Double bond here. Double bond here. And so, we've got each of the carbon to have extra hydrogen. Okay? Hydrogen.

[00:21:21]Hydrogen. Hydrogen. Hydrogen. Hydrogen.

[00:21:25]That makes it that carbon being able to form four maximum bond. Okay? Four maximum bond. So, I've been able to go with that principle. Okay? Each carbon now has four bonds around it. 1 2 3 4. Now, the next thing, how do we go about hydroxyl?

[00:21:43]From the word hydroxyl here, okay? It's a OH. And so, having one hydrogen, taking off, and replace by OH is what we have to meet hydroxyl benzene or what we call phenol.

[00:22:00]Okay? What I can refer to as phenol.

[00:22:03]Phenol is just a a common name to it.

[00:22:06]But, this is the actual molecular name, hydroxyl benzene. Okay? Now, that's why I said they are derivatives. Now, here also, the next thing, we've got 1 3 dimethylbenzene.

[00:22:18]Benzene here as a parent name. So, we've got to do benzene also as we did the other time. Benzene structure. Okay?

[00:22:27]Benzene structure.

[00:22:30]Okay? Ensure the benzene Okay, let me do it here because of the space.

[00:22:34]Now, here, carbon.

[00:22:36]Carbon.

[00:22:39]Carbon.

[00:22:41]Now, we've got carbon here to be six.

[00:22:43]1 2 3 4 5 6. Now, we get We go with the bonds. One. Okay? We leave the next one.

[00:22:50]Another bond here. We leave the next one. Another bond. Meanwhile, those bonds we've got here, they have the ability to resonate. Meaning, they can transit to the next. Okay? That's why we have most of the times benzene structure to be put this way. Okay, due to resonance. All right, so what let me now have it done that way and let me take it through the actual, you know, structure for benzene. Then like I said the other time, you've got each of the hydrogen carbon also to have an extra hydrogen, hydrogen, hydrogen, hydrogen. All right, so go with all the law, having each of the carbon having four maximum more.

[00:23:29]Now, the next thing is, how then do we have Now, we have the head methyl to be in two places.

[00:23:37]Now, methyl being dimethyl here means we've got that methyl to be attaching two places and where and where? In the position number one and position number three.

[00:23:47]Now, you can actually If you number one, I'll put the methyl here. 2 3. So, be here and here. I can actually work with that. Okay, if I decide here to be number one, that's be number one. 2 3. That's be here. So, now let me decide here to be the first one.

[00:24:08]So, I've got here to be a methyl attached here that CH3.

[00:24:12]A methyl.

[00:24:14]Now, the methyl are in three places.

[00:24:16]Sorry, two places. The first carbon position and the third carbon position.

[00:24:20]So, number one, number two, number three. So, you've got that replaced also by another methyl. All right, so we'll proceed to the next question very very quickly, you know. All right. So, move on to the next question.

[00:24:35]Hm?

[00:24:36]Yeah, now.

[00:24:37]Now, we've got another set of questions here to attend to very very quickly as well.

[00:24:43]Now, the next question here from where we stopped the other time says, give two physical properties.

[00:24:49]Physical properties of ethyne.

[00:24:51]Now, notice this here, physical, not the chemical. All right. Now, what are the physical properties of ethyne that we do notice? Now, we discover that ethyne okay, exists as gas or as gas at room temperature. Okay, so I can say number one, now it is uh it is less dense than air.

[00:25:23]It is less dense than air. And so, because we are comparing with air, makes it a gas. So, meaning that gas is denser than it.

[00:25:33]Now, that can also mean that any gas in that category where air is denser than the word dense to a layman means heavy.

[00:25:42]Okay, so it means that if I have ethyne gas here and I have air here, so I expect air to be heavier than ethyne gas. So, as a result of that, so it means that ethyne air will be displaced below. And so, on that note, ethyne can be collected by what we call a downward displacement. A downward displacement. Any gas less dense than air can fall in this category, okay, of being collected by downward displacement, okay? Then number two, physical properties of ethyne, I can also say that if if ethyne is being released here, it will have a characteristic sweet smell. Okay, being a hydrocarbon, it has a character characteristic sweet okay, smell, okay? We can go on and on, okay? Okay, for ethyne. It is a colorless gas.

[00:26:44]Okay, it is a colorless gas and the likes of that. All right, so here, now we are to calculate the volume of 0.25 mol dm³ solution of tetraoxosulphate (VI) that will contain a mass of 3.5 g of the acid.

[00:27:01]Now, given relative atomic masses here.

[00:27:03]Now, let's get this first.

[00:27:05]Now, let me get this on the line and let me explain what it means to a layman.

[00:27:10]All right. Now, we have to calculate what volume meaning that what exactly volume having this concentration Okay?

[00:27:20]Would Would you think will have exactly this mass of that acid? That's what it means. Now, let me go in again and let me re-evaluate it. Now, let me come from here.

[00:27:32]This here actually means concentration.

[00:27:35]Meaning that for that for this concentration, we've got it to be Let me solve some things here. I've got this to mean that there are 0.25 mol.

[00:27:45]Okay? Of the salt.

[00:27:49]Okay? Of the tetraoxosulphate (VI). Okay? Which I can say H2SO4.

[00:27:57]0.25 mol of H2SO4 we have it contained or dissolved in 1,000 volume.

[00:28:06]Notice here it was used as dm³ and 1 dm³ also means 1,000 cm³. So, I've been able to translate this first to a layman as this.

[00:28:16]Now, the next thing it says is Now, since I've got 0.25 mol to be in a 1,000.

[00:28:23]Now, firstly, how many moles do you think I will have in 500 volume?

[00:28:31]Okay? If there are these moles in 1,000, then having 500 volume, how many moles do you think I will have? Equivalently, since I have the volume, you know, reduced to half, then I should have the number of moles reduced to half, too.

[00:28:44]And so, the half of this, which I think will be uh 0. Let me get that. 0.25 / 2, 0.25.25 / 2. So, we've got that to be 0.125.

[00:28:59]So, it means that we would have 0.125 moles of the acid in 500, but that's not where I'm going to.

[00:29:07]This is exactly where I'm going to. Now, this mass of the acid, let me permit me to change this mass of the acid to mole.

[00:29:19]I will tell you what reason do I have to do that. Now, recall from I'm going to erase that from here. Recall that from mole equal to given mass over the molar mass. I'm just having to change this to mole. Let me know how many moles are there in this mass as well.

[00:29:34]Okay? Then this number stands for the given mass, 3.5 over the molar mass of H2SO4. Molar mass of H2SO4, okay? H2SO4, okay? The hydrogen being one here.

[00:29:50]And we've got two moles, two atoms of the hydrogen, two atoms rather. So, we've got that to be 2 * 1, okay? Plus sulfur, 32, okay? Plus 32 plus oxygen, 16, and you have four atoms. So, you've got that to be 16 * 4.

[00:30:06]So, we've got that to be 2 * 1, 2, plus 32, plus here you've got it to be 64.

[00:30:12]So, adding this up, you've got it to be 34, okay? That's 98. So, the molar mass here we've got it to be 98. So, you've got to divide 3.5, okay?

[00:30:24]3.5 to divide 98.

[00:30:30]Okay? Here, I've got that moles here to be 0.0357 moles.

[00:30:39]Now, what does that mean in another word, in another way, rather, it means that this 3.5 g of the acid equally means this number of moles.

[00:30:49]And let me say that again.

[00:30:51]This mass of the acid equally means this mole.

[00:30:55]Also, to say this mole of the acid will definitely also weigh 3.5 g. And since we were told from here that this number of moles will definitely be in a thousand.

[00:31:07]And asking us to find the volume that will contain this mass, meaning you have to find the volume that will contain this mole.

[00:31:15]Okay? Meaning that here, 0.0357 moles Okay? Of the same acid shall be contained in x cm cube proportionately with this. Very simple and direct. So, you go to cross multiply x times this.

[00:31:31]0.25 x Okay? Then you've got this 0.

[00:31:37]0357 times 1,000.

[00:31:41]Okay? Then you go to divide both side by 0.25.

[00:31:46]0.25 this is gone. So, we've got x to be equal to And let me divide that without a waste of time. Okay? Here alone times 1,000, you've got that to be 1 2 3.

[00:31:57]That's 35.7.

[00:31:59]35.7 to divide this directly. 0.25 So, you've got that to be 141.42 {point} 8 cm cube.

[00:32:13]So, it means that if I have this volume of the tetraoxosulphate (VI) acid having this concentration, I can be sure that it will contain this grams of the acid.

[00:32:25]That's the interpretation behind this very question. Okay? I want to believe you have gotten it. You got it right there. Okay? You can go search for questions that are similar to this and ensure that you actually got it right by having to solve those questions with the same principles you've you've learned here. All right, the next question here says we have to complete this table here given this series of element, we have to give their atomic numbers, their electronic configuration, and of course, the valence electron. Now, this is not here actually. I solved here. This is not here, too, actually. I solved here as well.

[00:33:01]Okay? This solving should have been done here. So, permit me. You can get that from there. All right. So, here we have the likes of beryllium, we have aluminum, and we have potassium. We have to deduce the atomic number. This is just straight asking us to determine or let's just quickly read through the first 20 elements. All right. We've got hydrogen, helium, lithium, beryllium being number four. Beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium. Okay? Aluminum here will going to be 13. Okay?

[00:33:34]Aluminum, silicon, phosphorus, sulfur, chlorine, argon, potassium. Potassium is next to calcium. So, that's it. That should be number 19. Okay? Number 19.

[00:33:46]And let's get it again. The first 20 elements, one, two, go. Hydrogen, hydrogen, helium, lithium, beryllium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, neon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, argon, potassium, potassium number 19, then calcium. So, we've got that potassium to be 19 here. So, the next question here says we have to give their electronic configuration here of each of them. Now, let me take us through this here. Their electronic configuration very quickly.

[00:34:28]Okay?

[00:34:30]All right. Here, now this is the way out. Now, I quickly label them. The suborbitals, we've got the S, we've got the SP, we've got the SPD.

[00:34:42]And of course, we've got uh think uh Okay, we've got another Okay, we've got another SPDF.

[00:34:53]Okay, so I can number this to be, right, 1 2 2 3 3 3 4 4 4 4.

[00:35:04]Okay, then I stroke them downward. I stroke them downward, all right? Now, this is what I mean here. You stroke them downward here, downward, okay, downward, downward, downward, downward, downward. So, that gives you the arrangement of which you go with them, knowing that the S has the maximum of two electrons. Okay, P has the maximum of six, difference of four. Now, the next one, SPD. Now, the four today becomes 10, maximum of 10, then F has 14 number of electrons. Now, going with those three domain here, now we've got the first element here as beryllium.

[00:35:40]Now, here, we've got beryllium to have four proton number, which is assumed to have four electrons as well.

[00:35:47]And remember, this configuration is not proton configuration, it's electron configuration. So, we assume number of electrons to be the same number of proton. Okay, for neutral element.

[00:35:57]Anyway, all right, so beryllium being number four means that it has four protons. In the other way too, it means that it has four electrons in the neutral state. So, four electrons, how do we do that? Now, the first one here, 1S.

[00:36:13]1S. And of course, you know, S can actually take two maximum, so 1S. Then after the 1S, the next is 2 2S.

[00:36:24]2S. Of course, we're still in the S orbital. Okay, S orbital. S can actually take two as well. So, I've got how many electrons all together? Four. So, means that I have filled completely the number of available electrons for beryllium.

[00:36:38]So, I've got to stop here.

[00:36:40]Okay? Now, we'll do the same thing for aluminum. Aluminum having three protons means that it has 13 Sorry, 13 protons means that it has 13 electrons as well.

[00:36:51]Now, let me go with the first, you know, the first sub orbitals. 1S. Okay? 1S. Of course, you know, S can actually take two electrons. The next shell is going to be 2S again. Okay? 2S. We can actually have the maximum of two again.

[00:37:06]Then, I've expended how many electrons so far? Four.

[00:37:09]And I'm heading for 13. So, I have how many electrons more? Nine. So, now let's move on to the next shell. The next shell is 2P before 3S since I'm going this way. 2P. Okay? 2P. And of course, I said P has to have a maximum electron of six. So, I've got six here.

[00:37:26]How many electrons so far? 6 2 2. And that's 10. I'm still heading for 13. So, after 2P, the next shell is 3S. Okay?

[00:37:37]3S.

[00:37:38]Okay? Permit me to drag it down here because of space.

[00:37:41]Okay?

[00:37:42]So, I've got this place here. 1S2 2S2. Okay? The next one 2P6. Okay? And of course, after the 2P, we've got 3S.

[00:37:52]Okay? 3S2.

[00:37:54]S can only take two maximum number of shells. So, I've got two plus two, four, 10, 12. So, I have one more. One more.

[00:38:03]The one more electron goes to the next room, and that's going to be 3P. Okay?

[00:38:07]So, I've got that to be 3P, then just one electron is available. So, I've got to stop there at the electron configuration. So, we'll move on to potassium. Potassium here, okay, move on on the same platform. 1S2 2S2 Okay? 2P6. How many so far? 10.

[00:38:25]3 S2 Okay, the next shell, 3 P6.

[00:38:30]Now, let me count how many electrons I've gone have I've gone here so far. 6 + 2, that's 8.

[00:38:36]8 + 10, 18. So, I've got one more electron to reach 19. So, 3 P. After the 3 P, the next room is 4 S.

[00:38:47]4 S. Ordinarily, S can take two.

[00:38:50]But, if I had two here, it becomes 20.

[00:38:53]But, here to make it 19, I've got just one more electron to put there.

[00:38:58]Now, the next one here is talking about the valence electron. Valence electron, please, it's not the same as valency.

[00:39:05]Valence electron simply means the number of electrons you have in the outermost shell of any given element. Now, let's go with that of the beryllium.

[00:39:15]So, let me do the configuration of beryllium. Beryllium, being number four, can be configured in the principal shell as two, you know, {comma} two. Two in the first shell and two in the second shell. Meaning that you've got two shells for beryllium.

[00:39:30]And the outermost shell has got two electrons on it. So, when we say valence electron, we mean the number of electrons we have on the outermost shell. So, for beryllium, the valence electron here has got to be what?

[00:39:45]Two.

[00:39:46]The next one, aluminum, being 13. Now, let me do the configuration. The principal shell configuration, that's two, eight. Okay, this is 10 so far, and three, making it 13. So, here I've got three shells. One shell, the next shell, the outermost shell. And here, the outermost shell has got how many electrons on it? Three. So, that tells me the valence electron of aluminum to be three.

[00:40:13]Okay, valence electron. Okay, then potassium, being number 19, I've got to do the configuration of that also to be two, eight. That's 10 so far, okay? Then another eight, being 18 so far, then I've got to reach 19. I need just one more. So, on this aspect here, I've got four shells. The first shell, the second shell, the third shell, and the fourth shell. So, on the fourth shell or the outermost shell, I've got just one electron there, and that becomes the valence electron, number one.

[00:40:46]All right. Now, move on to the next one.

[00:40:48]The next question says we are to state periodic law.

[00:40:52]Periodic law, okay? That is the law that governs the arrangement of the element in their respective position. So, we said here that periodic law here states that the chemical properties of element, also to say the properties of element, are the periodic functions of the atomic number. So, let me have it written down here, okay? This state This state All right, that Okay? That the properties of element are a periodic function.

[00:41:40]Are a periodic function of their atomic number.

[00:41:54]Okay? If I were to explain that to a natural being, it means that, you know, their chemical behavior The chemical behavior of any element is a function or is caused by their atomic number. So, it is the atomic number that determines the way they behave or the property they exhibit.

[00:42:18]That's what it means. This states that the properties of an element are a periodic function of the atomic number, right? So here, not to waste our time, we have to consider the following element, element A, B, C, D. Now, we're given these elements, we're not told exactly their names, but we're told their respective atomic number here.

[00:42:38]Being the subscript here, atomic number 3, 11, 13, 17. So that will give us an idea to an extent what nature of element they actually asking us about or talking about. Now, they said here, "Which of the elements or element has the highest electronegativity?"

[00:42:55]Now, the question is, "What are electronegative elements?"

[00:42:59]Now, very simple, electronegative elements are elements that has the tendency, okay, tendency of absorbing, okay, or of, you know, having to, you know, to take in an electron, okay, in order to attain configuration, in order to attain stability, however the case, okay? Now, there are some elements that they will have they tend towards accepting electron to attain stability, meanwhile, there are some who tends towards giving out electron to attain stability. So, the categories of elements that will rather take in to attain stability, they are referred to as electronegative elements.

[00:43:40]Okay? They Okay, but those who will attain configu- uh stability by rather giving out electrons, they are referred to as electropositive elements. So here, which of them has the highest electronegativity from among this? Now, how do we know this? We wouldn't know from this labeling, we'll rather know from the atomic numbers.

[00:44:01]Okay? The atomic number of that of A, okay, being 3, tells me that you've got that to be the configuration to be 2 2 1, which means that the valence electron here is one. It belongs to group one element. And group one element are nothing close to being electronegative anyway. The next one, B with atomic number 11. Okay? The configuration tells me 2 8 then 1.

[00:44:27]Then you've got this also to be in group one, being the valence electron. That reminds me. The valence electron here, like I said the other time, they are elements in the outermost shell and also their numbers are the time it the group in which the element in question belongs. So, it means that beryllium being having a valence electron of two belongs to group two.

[00:44:47]Aluminum having a valence electron of three belongs to group three. Okay?

[00:44:51]Potassium belongs to group one. That's exactly what it means. All right. So, here now see, let me explain this to ex- see, having an atomic number of 13, okay? We've got that to be 2 8, okay? 2 8 then 3 here. So, I've got this one to be in group three.

[00:45:10]In group three. Okay? Now, let me do the very last one there, element D of atomic number 17. We've got that to be 2 8.

[00:45:17]Okay, that's 10 so far.

[00:45:19]And another seven.

[00:45:21]Now here, this is an electronegative element among them because this will attain stability by having to take in one extra electron to make it stable such as eight.

[00:45:36]Okay? But this one will rather give out the three to become stable.

[00:45:42]Okay? And so, now here, this one tends towards being electropositive anyway.

[00:45:47]While this tends This is not This is This is exactly electronegative. Rather, it will attain stability by having to invite one more electron into the outermost shell in order to attain stability of eight, octet stability. So, you've got that to be element D. Okay?

[00:46:04]Element that has the highest electronegativity will be element D.

[00:46:08]Okay? As this. The next question here, element that belong to the same group in the periodic table. Like I said, how do you know elements of the same group? Or what determines their group? What determines their group is simply their valence electron.

[00:46:21]And something else determines their period. Period are determined by the number of shell. And let me get us through this.

[00:46:28]Now, element A has got how many shell?

[00:46:31]One.

[00:46:32]Two. Two shells. Element B has got how many shells? Three. One, two, three.

[00:46:39]Three shells, three shells, three shells. That means that element B, C, D will definitely belong to the same period.

[00:46:48]Okay? So, what determines period is simply number of shell.

[00:46:56]Number of shell determines period. Meanwhile, group is determined by valence electron.

[00:47:04]Okay? Valence electron. Now, let me check Let me check through that, too.

[00:47:08]Element A and B has got to have the same valence electron, one, one. So, it means that A and B, however, we do not know what they have, will definitely belong to the same group. That's what it means.

[00:47:20]Now, belong to the same group here means element that have the same valence electron. That's going to be A and B.

[00:47:27]So, you've got that to be element A and element B. So, we've got the answer to be this. The next, we're moving to the end of the question gradually. We have to name this compound here. Let me take this off. We have to name this organic uh compound here. Now, the first thing we need to do is in naming an organic compound, the first thing is identify the functional group.

[00:47:49]Identify Number one, identify. Let me identify it. Go to functional group to be here. Meaning it is what? All. It belongs to the homologous is called the alkanol. So now, that's the first thing, identification of functional group, which I've done that. All right, so the next thing is actually identify the longest carbon chain.

[00:48:11]And let me say it again, identify the longest carbon chain. How do I mean?

[00:48:14]Now, let me see.

[00:48:16]1 2 3 carbon, 4. I've got four carbon.

[00:48:21]Could that be the longest carbon chain?

[00:48:23]Let me see if I can have five. 1 2 3 4 5. I'VE GOT FIVE. LET ME SEE IF I can have six.

[00:48:32]1 2 3 4 5. Still five. And so, I've got the longest possible so far to be five.

[00:48:40]Now, having done that, that's rule number two. Then rule number three, then I would number the five carbon that I've been able to deduce or discover. Okay? In such a way or direction that the carbon carrying the functional group has the least possible number.

[00:48:58]Let me say that again. Now, I have discovered the longest chain to be five, okay? So the question is, how do I number the five? Do I number 1 2 3 4 5, or I number 1 2 3 4 5? So there's the correct numbering, and there is the non-correct or the wrong correct the wrong numbering, rather so to say, pardon me. All right, so here, now which of the numbering would you go with or is most correct? This is it.

[00:49:21]>> [clears throat] >> Now, you number in such a way, okay, let me do for example, now let me let me say for example, let me number from here. 1 2 3 4 5.

[00:49:32]I decide to number this way, and the carbon that is carrying the functional group OH falls on carbon number two.

[00:49:40]Now, let me see if I number from here, let me see the difference. 1 2 3 4 5.

[00:49:50]Now, notice I number from here, 1 2 3 4.

[00:49:54]So, here it is the fourth carbon that is carrying it here. But, numbering from here, it is the second carbon that is carrying it. So, the question is between the second here and the fourth here, which one is smaller? The second. So, the smallest number carrying the functional group is the most correct numbering. So, I have to excuse this one here as being not correct. Okay, I'm sure you got that there. So, I've been able to get the correct numbering. So, that means that the other carbons that were not numbered will be circled as an attachment. They are not part of the carbon chain. So, I label them as an attachment. So, they are called the methyl methyl, like I did the other time for benzene, 1 3 dimethylbenzene. So, this are methyl from alkyl functional group. All right, so here, the next thing I do is I name the attachment first. Being both of them methyl and third and fourth carbon, so I've got that to be three Okay. Four That is methyl on number three, methyl on number four. So, I've got that to be three four. Okay, die methyl Okay, 3 4 dimethyl. The chain The parent chain is five. Five is pent. So, go down to be pent.

[00:51:10]Then, it has to end with all being the functional group weight. So, pentanol.

[00:51:16]So, let's go down it again. 3 4 dimethyl pentanol. Quite interesting and direct.

[00:51:22]So, let's move on to the next code.

[00:51:24]We're approaching the end of the question gradually. Here, given the equation, nitrogen plus the oxygen gas to form two moles of nitrogen dioxide. Okay. Now, gaseous. Okay, of course, gaseous here as well. Gaseous.

[00:51:39]Now, but notice the symbol here. Okay, the enthalpy change has been positive.

[00:51:45]Meaning that such reaction is said to be endothermic reaction.

[00:51:50]Okay? Now, this delta H being positive means that it is a heat loving reaction.

[00:51:56]So, I can also call it a thermophilic reaction. Thermophilic. If it is the other way, I can also say thermophobic reaction as I explained, not heat loving. But this very reaction tells us that it is heat loving. Meaning that if you take away heat from it, the reaction would not proceed.

[00:52:14]But if you give heat to it rather, the reaction proceed. Which means that it loves heat. Heat is needed for the reaction to proceed. That's what the symbol here means.

[00:52:23]Endothermic reaction. Okay? Now, here, state one factor that will bring greater yield of the product. Now, not of the reactant, of the product. Meaning one factor that will help the reaction to proceed in the forward direction. You've got two directions for the reaction. We have got we've got the forward direction, we've got the backward direction.

[00:52:49]Okay? The forward direction, the backward direction. Now, I've always told student, if you have the forward reaction to be endothermic, then it is always assumed that the backward will be the reverse. That is, it will be an exothermic reaction. Meaning that if it is heat loving forward, it will be heat not loving backward.

[00:53:10]All right? Another time to say heat loving, if it is thermophilic forward, it will be thermophobic backward.

[00:53:17]Okay? It will be thermophobic backward.

[00:53:19]Now here, state one factor that will bring a greater yield of the product. Meaning that what can I do to this reaction to have more of nitrogen two oxide formed?

[00:53:31]Okay? To have more of the product.

[00:53:33]Meaning to have the equilibrium position shift to the right. That's another way to explain it. Okay? Now, notice that the reaction like I said the other time is endothermic, that is heat loving. So it means that if I had more heat to this reaction, I should expect the reaction to to proceed in the forward direction.

[00:53:51]Okay? All right. So here I can say increase increase in temperature.

[00:54:01]Okay? Now we've got the next question to be reasons on why we chose this thing.

[00:54:06]Now here they said give a reason for your answer in the above.

[00:54:10]Now the reason for this is because the reaction the reaction represented is said to be an endo thermic.

[00:54:32]Okay? Endothermic reaction.

[00:54:35]Okay? It's said to be an endothermic reaction which would definitely love heat to proceed. So at this point, I want to say um congratulations and a very big thank you to okay, to you particularly who have stayed even to this very time on this very class. I want to say a very big thank you to you once again and I want to wish you all the very best in the exams in the course of the week chemistry. Okay? So I I can't even wait to have your good compliments and your good commendations and your testimonial.

[00:55:09]Of course, as regards this class. All right. So do well to let's have a review of the things that you have given out here the the the principles if I told that are little principles here. Okay?

[00:55:19]Unlike physics, there's more principles and concepts. But however, what you have learned here, just do well to you know, revisit them to validate the fact that you've actually learned them and you would definitely have questions. Okay?

[00:55:31]As this in your forthcoming exams. Okay?

[00:55:34]In chemistry NECO theory 2026 revision.

[00:55:38]So at this point, I want to a very big thank you. I want to put an end to it there. So do well to just subscribe.

[00:55:42]Okay, like and share if you are just having to come in contact with this you know channel for the very first time.

[00:55:48]Okay, so would I wait. And of course we have the comment sections for any observations or questions that you may have concerning our classes or the previous class that we've actually done on the same channel. Thank you very much and God bless you.