MOSJARO is live!

Ajouté : 2026-05-05

[00:01:24]Um, All right. Um, good morning everybody.

[00:01:32]Let's begin the class. Like I said before, there are some questions or there are some things I need to bring to your mind as you prepare for the examination.

[00:01:45]Um please if you cannot see very well just let me know so that I'll be able to um arrange the camera very well and make it brighter. But I think uh we are good to go. I just want to bring out some few questions that I'll be targeting today.

[00:02:04]There are some persons that are writing tomorrow. So this class might not just be for today alone because like I said we having the class today.

[00:02:13]um in the evening. We're also having the class in the evening. So, let's just take if it's 1 hour or 45 minutes this morning and review some things very very quickly. Like I always say, I always drop the how will I call it now? I always drop the um the topics that you need to look at um as you're preparing for this examination. First of you have to consider looking at atomic part of chemistry. I always emphasize on it because there's no exam that you prepare for that you will not come across questions from this aspect but might not be starting from there today but I just want to put at the back of your mind that you must pay attention to atomic aspect of chemistry. Now this is the last straw but I've changed my mind about these classes that of course this evening I'm going to upload another video looking at questions but this one is live um like I said before. Okay. Now there's one question that I am having here. There's one question I'm having here. They said which of the following is odd? Like which of the following is odd? Like which of the following not join? Now let me bring out the um options very very quickly. Let me bring out the options. They said which of the following is odd in those options? They said A.

[00:03:54]They said A. We are having A. They said A is aluminium ion. Then B we have sodium ion. Then they said C we have oxygen ion. Then of course they said D we have what? We have florine. Now they said which one is odd. Now I use this question to bring out something. Which of the following is odd amongst all of them? Now the question is somehow because if you want to look at it in terms of elements, you not be thinking that oh uh this element is aluminium, this one is sodium, both of them are metals, this one is oxygen, this one is florine, these two are nonmetals. But why are they not asking us which of the following is odd amongst them? Now first off if you look at aluminium on its own you know that aluminium have 13 electrons.

[00:04:46]Now you know that sodium on its own have 11 electrons.

[00:04:52]Now oxygen has eight electrons while florine has what? Nine electrons. I mean talking about their neutral atoms. Now if you are looking at their neutral atoms. Now if you look at aluminium the L3+ here what does is what is um is 10 because normally oxygen is eight. You get me now? So oxygen is eight. So this 2us is not 10. So if you look at it now this guy this guy this guy the same number of what of electrons and elements with the same number of electrons are said to be what? Iso electronic elements. Iso electronic elements they having the same number of what of electrons. So look at aluminium look at sodium look at oxygen. But if you look florine florine is not our answer is the odd one out. The reason being that florine is what is having normal electron of nine. So there are two things I want you to put at the back of your mind. First of all is that number one the first thing there is that first that aluminium has 10 aluminum ion not aluminium. So aluminium on it own has 13 ion has 10 oxygen ion has 10 now. So if all these element all these species let me call them species they having the same number of electrons. Now elements with the same number of electrons are said to be is electronic.

[00:06:15]So let's look at all the iso you know we have is electronic we have the isotones these isotones they have the same number of neutrons and of course we have now what this is these isobars give or take is just like opposite of isotopes now that this see elements that have the same atomic mass maybe 14 but they have different atomic what number that is isobarism now I just want to go from you know with a talk let's look at the basic part of chemistry first before we begin to look at some other parts.

[00:06:48]Now remember I said there's a put at the back of your mind. Now let's begin to analyze each of the following. So when you are studying in this jam examination okay now if you want to understand chemistry fully make sure that you are looking at each of for instance now aluminium check aluminium look everything about aluminium there's one question that comes out in aluminium because normally I don't ask her for class sometimes aluminium one should you No what's it called part. Now if I ask you which of the following metal is the lightest metal of course the answer there is what is lithium. Lithium is very light. Now at the back of your mind now lithium is very very what light. Now another thing you must know about aluminium. Remember aluminium is used in process. Al we don't talk before for class. So if you don't know it now that aluminium is used in the what process.

[00:07:50]Now tell me process is used for welding and it's used to purify metals. Now two things this process is used for welding and is used to do what? To purify it's used for welding and it's used to purify net. So a very quick one very very quick we'll be dropping it little by little but there are two things I've said today. Now this question number one say which the following is odd. Now we have been able to look at it. Now you know what's is electronic element?

[00:08:16]Element have the same number of electrons. We have isotones element have the same number of neutrons. We have isobars. They have the same atomic mass but different atomic the same atomic number but different atomic massing again. Now we're still looking at some certain things that you know you know that this metal this metal sodium is more reactive than aluminium. Now I want to bring out another question. Um give me few seconds. Let me bring out another question on this aspect of elemental chemistry. Now just give me a few seconds.

[00:09:22]All right. Now look at this question.

[00:09:26]Look at this question. I don't know if you can see this question prop. So all you have to do is that stay tuned so that to follow up. Now let me go let me go back to this question. Now this question is on the board. I don't know if you can see very well but back to this question. Now this question is on the board. I don't know if you can see very well but I'm going to read it out.

[00:09:46]Now this now a metallic ion that means it's a metal a metallic ion x2 plus with inert gas structure contains 18 electrons inert gas. Now look at the word inert gas. Of course you should know that this inert gas there. So they be call of course noble gas. Show you this now. So if he has a a noble gas structure that means it has a filled atomous shell.

[00:10:14]Get go back again. I mean you understand a metallic ion that mean the metallic ion 2 plus 93%. Now a metallic ion X2 plus with inner gas structure gas structure with me say the atmosphere should you remember say the inner gas or no gas what they talk to we have we have neon we have krypton we have zenon and we have radon now but talk say the inner gas structure with this metallic ion get x2 plus now this two plus you know say it don't lose two electrons. Now X2 plus the after two electron the composite the metallic ion can't get inner gas structure of 18 electrons and if you look at it very well you notice that argon has the same number of electron as they said how many protons are there in this ion. Now I want to emphasize on this please break it down that um how will I put it now that the proton does not change. Now let me give you an instance. If I have an element X and I have an a specy of X2 plus maybe this one is let me say for instance maybe this one is let me use sodium for instance. Okay let me use sodium a practical one let me use sodium this is sodium this is sodium ion say sodium 23 atomic mass 11 atomic number. So this one 23 atomic mass 11 atomic number bro the atomic number not they change and what the atomic number you know say atomic number and number of protons. So the atomic number they change the atomic mass not change what they change now the number of electron. So the number of electron here normally 11 because for a neutral element number of proton is equals to number of electrons.

[00:12:11]But when it comes to this guy you know say the number of protons is not equals to number of electron. Do you know why?

[00:12:18]Because this guy has lost one electron.

[00:12:21]So the electron is now 10. But the number of proton remain the same.

[00:12:24]size. So for both a a neutral atom and an ion the number of proton does not change. It remains the same. Now going back to our question if you look at here they said x 2+ that when it be x2 plus the number of electron is 18 that mean before it go be x2 plus it will be x. Now, now if it be X and it be X2 plus electron 18 that is not lose two electron that is originally he get what he get 20 electron. So if you get 20 electron that mean you get 20 proton you grab. So the number of the number of proton here. So they said how many protons are there in this ion? Remember protons not the change. So continuous 20 they said that it as the structure contains 18 electron for it to contain 18 electron and the metallic by two plus that means it has lost two electron for it to lose two electron to form 18 electron that mean originally it has 20 proton so the 20 proton does not change so it's only the electron that what that changes feel the same now so we able to bring out two important question from basic part of chemistry the first question You go look at the second one.

[00:13:40]This one you have to think about it.

[00:13:41]They ask this kind question where they ask what I want to establish here is that number of proton they change number of neutron change. So they can say what is the number of neutron you able to bring it out very easily.

[00:13:55]You get it now. So I want to bring out another important what question for us.