 Right on the heading group two, which is alkyline earth metal. Yeah, once again, then okay. Okay, you see the group two elements, we also have the same kind of properties. What difference we have that we'll see obviously, but you know, like in general thing top to bottom if you go electronegativity decreases size increases ionization enthalpy decreases. These kind of properties are same over here. Right. It is not going to change. It's very simple and same we have. Okay, so what all elements are there in group two, the elements which are present in group two are. We have beryllium, magnesium, calcium, strontium, barium. And last one is what friendship isn't group one. Okay, these are the compounds we have. If you look at the electronic configuration here, beryllium has five sorry for electrons atomic number four. So it is one s to two s to configuration. Okay, belongs to the second period, magnesium belongs to third period atomic number 12. So it is one s to two s to two p six and three s to similarly for calcium it is four s to outermost configuration strontium it is five s to and so on will go. Right. So general outermost electronic configuration is NS two. Can we say that, like for the first, you know, group we have NS one here general easy electronic configuration general outermost electronic configuration is NS one. Sorry, NS two, I'm sorry, NS two where n is the period of the element. Okay. If you talk about some general properties like if I say atomic and I need radius in short I'll write down okay because we have discussed these things in group one. So atomic radius and I need radius. So we know as we go down the group one extra energy shell is getting added right and hence down the group atomic and I need radius increases. We go down the group atomic and I need radius increases increases. Okay, both. So the group size increases size increases so ionization enthalpy. Tell me ionization enthalpy decreases down the group. If you compare this with the first group of element. So for group one you see the electronic configuration is NS one and for group two the electronic configuration is NS two. So if you compare the first ionization energy, because of its stable configuration, the IE one first ionization energy of the elements of group two is greater than to that of group one. This order you understood, no doubt. If you compare IE two for group two and IE two for group one, what would be the order IE two for group two and group one. If you look at the configuration of IE two of group two and group one group two will be lesser because group one has stronger or stable configuration. It's opposite over here. Okay, even if you talk about the ionic size. So the ionic size of group one element is more than to that of group two left to right as we go in a predictable. We have discussed this in periodic properties left to right effective nuclear charge increases ionic radius decreases. So group one elements are relatively, you know, more in size in comparison to the corresponding group elements of group two. Okay, these two properties we have. When you talk about the oxidation state. Third one. Second is what a second order that I did it other way. Let me check this. It is other way around. Yeah, by mistake so it should be this IE two of group one is more than to that of group two. Yeah. Next write down. Third one is the oxidation state. What is the possible oxidation state for the elements of group two, the possible oxidation state of elements of group two is plus one and plus two. Obviously the plus two is more stable oxidation state. Okay, so write down alkaline earth metal shows shows a stable plus two oxidation state shows stable plus two oxidation state stable plus two oxidation state. Okay, because two electrons in the outer motion, so it can easily lose the two electron to gain the stability. Right. So this is what we have we can also understand your bond hyper cycle that we have already discussed in periodic properties. Okay, right on one note here, the second ionization in Thalpe's of alkaline earth metal, the second ionization in Thalpe's of alkaline earth metal is almost twice is almost twice of first ionization energy is almost twice of first ionization energy. And hence they form by violent molecule, hence they form by violent molecule, they form by violent molecule, rather than monovalent compound. There is a simple where it loses to electron it has the stable configuration inert configuration, and hence it forms these compounds right. So oxidation state is plus two possible. Okay, melting point and boiling point right now wait first right on electropositive character. As you go down the group what happens electropositive character. Electropositive character is what the tendency to form a positive charge iron. Right. So we know as we go down the group, the ionization energy decreases that tendency to lose electron is more right and hence the electropositive character increases right so right on as we go down the group. The electropositive character increases the order is barely a magnesium calcium, is strontium and then barium electropositive character. And the same thing we have for metallic character, the tropositive nature, and also we have this for metallic nature. Okay, both increases down the group, because ionization energy decreases. Okay, some physical properties we see right on melting point and boiling point, melting point and boiling point right down the melting and boiling point of of alkaline earth metal, the melting point and boiling point of alkaline earth metal is higher than is higher than to that of is higher than to that of that corresponding is higher than to that of the corresponding alkali metals. And what is the reason for this melting point and boiling point. Write down one more point to write down after this, we have just discussed that alkaline earth metal will have higher melting and boiling point and alkali. What happens as we go down the group. Okay, so write down the next line as we go down the group, as we go down the group, the metallic bond, the metallic bond strength decreases. Metallic bond strength decreases. Hence, in general, in general, in general, the melting and boiling point decreases, in general, melting and boiling point decreases. But there is no regular trend here means in general it happens down the group decreases. But in case of alkaline earth metal, there is no general trend. Okay, the trend is irregular sometimes decreases increase and like that. Okay. But if you talk about alkali metals, for alkali metals down the group the melting point boiling point decreases. The reason is metallic strength decreases bond strength decreases. Right, but if you talk about group two elements down the group, there is no regular trend in the melting and boiling point of alkaline earth metal. Right, two, three reasons are there different size, different structure that they adopt, plus the metallic bond strength also we have. Okay. So what you can keep in mind, beryllium if I write down the values here you see for beryllium for beryllium the melting point is I'll write down the two table here melting point and boiling point. The melting point, boiling point both are in Kelvin. Okay, in general, just one point one thing you have to memorize. Like you see, if you talk about beryllium, for beryllium the melting point and boiling point both are maximum. 1560 is the melting point and 2750 or 45 is the boiling point. Then we have magnesium, calcium, strontium and beryllium. So for magnesium it is 924 and this one is 1363 you see it becomes almost half the value. Right, then again it increases 1124. For this one again increases 1763. Then it is 1062. It is 1655. It is 1002 and 2078. Obviously these values you don't have to memorize but you see the melting the boiling point order is important here. Beryllium has maximum and then we have beryllium. Okay, after beryllium we have beryllium these two things you must remember. Copy this down. Okay. The next trend we have for melting and boiling point they don't ask you the entire trend but sometimes yes they may ask that which one has maximum boiling point or minimum boiling point something like that. Okay, but we don't have any regular trend over here. Okay, now the thing is next here that is hydration enthalpy hydration enthalpy is important. So next write down the sixth point hydration enthalpy. As we go down the group as we go down the group, the hydration enthalpies of alkaline earth metal ions decreases. Okay, as we go down the group, the hydration enthalpies of alkaline earth metal ions decreases. So the reason is write down. As we go down the group, like what happens here. Down the group size of the size of metal ions means M plus two ions increases size of M plus two ion increases as a result what happens. The charge density charge density decreases what is charge density and hence degree of hydration decreases and hence degree of hydration decreases charge density means charge per unit volume. Okay, charge divided by volume of the ion metal whatever it is that is charge density whenever you see density term is associated with charge or something like that, then we always consider per unit volume. Sometimes they also write charge per radius ratio, which is nothing but the same thing like terms are different but a result will be same if you consider volume or radius ratio. Okay, one note you write down the hydration enthalpy, the hydration enthalpy of group two ions of group two ions is four to five times greater than four to five times greater than to that of group one, to that of group one ions. Next write down the nature of compounds, nature of compound formed. So elements of group two predominantly forms ionic compound. Okay, it forms ionic compound. Hydrogen also we have seen their forms ionic hydrides. Okay, if you remember, ionic compounds they form. The reason is due to their low ionization energy, due to their low ionization energy, it can easily lose electron and forms ionic bond. Now the ionic character write down as we go down the group, down the group, the ionic character increases. Why it happens? Any explanation for this? Why ionic character increases as we go down the group? Yes, a smaller cation can polarize an ion, right, and hence the Faisal's rule the polarization decreases as we go down the group. Polarization decreases and hence the ionic character increases because we know polarization leads to the ionic character in the compound. Write down one note here, beryllium compounds, beryllium compounds in beryllium compounds in anhydrous form, in anhydrous form when there is no water of crystallization in anhydrous form are covalent in nature. Hydration, it becomes ionic. Hydration, it becomes ionic. The reason is very simple in anhydrous form, the charge density of beryllium ion is high and it can provide high polarization. Write down in anhydrous form, the charge density of B, plus two is high and hence it provides high polarization which leads to covalent nature. So whenever the question is about this thing, ionic and covalent, you can think of Faisal's rule, simple. You must have the option with option and then Faisal's rule, you can find out the best possible answer that you could have. So always take care of that, especially in S block. Here the Faisal's rule valid because if you remember, Faisal's rule is valid only for ionic compound. Perfectly covalent compound like CH4 and others, Faisal's rule are not valid. In ionic compound only we can say the percentage ionic or percentage covalent corrected, whether it increases or decreases down the group or not. So in S block for this thing, ionic and covalent concept, you can think of Faisal's rule, keep that in mind. Now next write down solubility and lattice enthalpy, 8-1, solubility and lattice enthalpy. Lattice energy of group 2 elements, lattice energy of group 2 elements is much higher than, is much higher than to that of group 1. Lattice energy is much higher because the size is less. So lattice energy of group 2 elements is much higher than to that of group 1. The reason I said because of size decreases. Write down for alkaline earth metal, alkaline earth metal as we go down the group, as we go down the group, as we go down the group, lattice enthalpy and hydrogen enthalpy, lattice enthalpy, hydration enthalpy decreases, enthalpy decreases, the size increases as the size increases. So if lattice energy decreases, this means what? Solubility increases. So solubility and lattice energy is inversely proportional, inversely proportional to lattice energy. More lattice energy, easy to break, difficult will be the break the bond and then solubility will be less. Next write down, we'll see different types of compounds that these elements forms. That is the nitrides we have, oxides we have, hydroxides we have, hydrides, all these things, correct? Carbonates, pycarbonates, all these things. So write down first of all, chemical reactivity. Again, as we go down the group, size increases, ionization energy decreases. Tendency blues electron is more, it can easily form plus 1, plus 2 oxidation instead and hence the reactivity increases. So reactivity order is minimum for beryllium, magnesium, calcium, strontium and beryllium. This is the order we have, okay? Chemical reactivity. Again, like I said in the last, you know, the same class, the first element of all the groups will have some abnormal properties, abnormal behavior. And that is true and valid here also. Beryllium will have some abnormal properties here. First reaction we are going to see here, that is reactivity towards air, towards air. Write down, due to increase in electropositive nature, write down like this, as we go down the group, down the group, the electropositive nature, the electropositive nature increases. And hence, reactivity towards oxygen also increases, towards oxygen increases. On all these elements, beryllium and magnesium does not react with oxygen easily. They form an oxide layer on its surface and hence the further reaction is hindered, okay? But at higher temperature, the reaction possible, okay? So write down at this point, beryllium and magnesium, B, E and M, G are kinetically inert towards oxygen due to the formation of a thin oxide layer on its surface. Kinetically inert means the reaction rate is negligible, it's extremely slow. Kinetics means, you know, the flow of reaction, how the reaction proceeds. So kinetically inert means the reaction rate is extremely slow and we ignore that, like okay, the reaction is very difficult to proceed because of the low rate and hence we ignore that. Means it's not like the reaction is not happening, rate of the reaction is very slow. So this is important for beryllium and magnesium, but at higher temperature, write down, but at higher temperature, they reacts with oxygen and nitrogen, atmospheric oxygen and nitrogen, forms oxides and nitrides. So what type of oxides and nitrided forms that is important? For example, you see, 2Be plus O2 from air, it gives BeO. The temperature we are using, 873 Kelvin or more than this. What is the reaction to proceed? With nitrogen, you see, 3Be plus N2, again this is from air only. So it converts Be3N2, beryllium nitride. Magnesium also, you see, reacts with 2Mg plus O2 in presence of air. When we heat this, it converts into 2MgO, 3Mg plus N2, it gives Mg3N2. What factor is going on in school? Thermodynamics? Okay, fine. Next slide down, reactivity towards water. Here also you see, the reactivity increases down the group and all these metals reacts with water and forms hydroxides of MOH whole twice and hydrogen gas eliminates you. 2H2 we are taking. This is the general reaction we have. Remember, first a group one, it forms MOH type hydroxide. Here it forms MOH whole twice because the valency is 2. Again, you write down reactivity, it decreases down the group. Could you tell me the reaction of alkali metal with water? Exothermic or endothermic? Exothermic or endothermic? High amount of energy releases. Correct. Okay, same thing we have here also. Okay, but the amount of energy releases is lesser than to that of group one element. Okay, right on this point. The energy releases, the energy releases, this you write down here, it is exothermic first of all, plus heat. And then the energy releases is lesser than to that of alkali metals. Hence the reaction is less vigorous. Very important point to write down in this note. First point, beryllium since forms oxide layer on its surface. Beryllium since forms oxide layer on its surface, oxide layer on its surface, does not react with water, does not react with water, does not react with water at all. Does not react with water at all. Next slide. Magnesium also forms oxide layer, protective oxide layer. It does not react with cold water. It does not react with cold water, but it can react with water at high temperature. So basically at high temperature or boiled water, the oxide layer breaks down. Okay, and the reaction possible. So beryllium does not react at all. Magnesium not with cold water, but reacts with hot water. All other elements are simple. They react with water as it is. Reactivity, we know it is as you go down the group, reactivity increases. Okay. We already know about hydrides. Okay, just to write down quickly. Reactivity towards hydrogen. We already know about hydrides. Okay, just to write down quickly. Reactivity towards hydrogen. We know these elements react with hydrogen and forms hydrides of MH2 type. Okay, all these hydrides are ionic in nature, except what? Except, yeah, tell me. BEH2 and MGH2. BEH2 and MGH2. The first two elements, they are covalent. Because of the small size of cation, more polarization, covalent nature is there. Next, write down reactivity towards halogen. Reactivity towards halogen. Write down. Elements of group 2 reacts with halogen, elevated temperature. At elevated temperature and forms, and forms halide of MH2 type, halides of MH2 type. So the reaction is any element M plus X2. We heat this and it forms MH2. Halides. We can also get halides when metal reacts with HX. Okay, it forms MX2 plus H2. When metal oxide MO, reacts with two HX again. It forms MX2 plus H2O. Carbonate, if you see. M2CO3 plus HK, HX, sorry. HX, it forms MX2 plus H2O plus CO2. Hydroxide, if you see. MOH twice plus HX, two HX, it forms MX2 plus two H2O. Done, copied. Okay, one more reaction here, write down. Reactivity towards acid and base. Reactivity towards acid and base. Elements of group 2, elements of group 2, reacts with acids and liberates hydrogen, H2O. Metal M reacts with, suppose H2SO4, forms MSO4 plus H2O. Same thing we can write for HCl also. For concentrated HNO3, if you see. M plus HNO3 gives MNO3 twice and H2O, hydrogen gas, evolves. This happens when HNO3 is very dilute. The reaction is important for HNO3. If any metal reacts with HNO3, but this HNO3 is not dilute now, not very dilute now, concentration of HNO3 also matters a lot in this reaction. Very dilute eliminates H2O. If you take dilute acid, then it evolves nitrogen monoxide gas. 3MG NO3 whole twice plus 2H2O plus H2O. Sorry, 2H2O plus 2NO. MG NO3 whole twice plus H2O plus H2O. Nitrogen monoxide evolves in this. Condition, you must remember, very dilute gives you hydrogen, dilute gives you NO. All these HNO3 reactions are very important. Note is what here? Important point, beryllium is inert towards HNO3. It does not react with it. And this we call it as, it is rendered passive. It goes passive with it. Beryllium is inert towards, beryllium is inert towards concentrated HNO3, towards concentrated HNO3. Reason is again the same thing. HNO3 is a strong oxidizing agent and it forms a layer of an oxide on the surface of beryllium. Further, reaction is not possible. Beryllium does not react with it. Next point, beryllium is amphoteric in nature. Beryllium is amphoteric in nature. Beryllium is amphoteric in nature. Amphoteric means what? Anybody? What do you mean by amphoteric? No. Yes, you can say like that. Amphoteric means it reacts with both acid and base. So you can say both types of characteristics. So beryllium is amphoteric in nature. It reacts with base, like for example you see, Na plus, NaOH we have a base, 2 NaOH plus beryllium in presence of water. It forms sodium beryllate. Sodium beryllate, the molecule is this, Na2BeO2.2H2O and H2 releases. If you look at the structure here, Na2 we have and Be will have 4 OH associated like this plus H2. This or this, anyone you can write on this product or this product. The last thing you write down before the break, solution in liquid ammonia, very similar to the previous one, that is group 1 element, like alkali metals, alkali earth metals, except beryllium. Okay, alkali earth metals, like alkali metals, alkali earth metals, except beryllium, dissolved in liquid ammonia, dissolved in liquid ammonia and gives blue color solution, dissolves in liquid ammonia and gives blue color solution, blue color solution, which contains solvated electrons, which contains solvated electrons. So reaction is metal, which is not beryllium obviously, X plus 2Y NH3 converts into MNH3 X2 plus plus electron, which is surrounded by ammonia, and we call it as solvated electron 2E minus. Okay, so because of this only, it shows blue color. This is the same thing we have blue color solution and solvated ammonia, same thing. One note in this you write down, magnesium does not dissolve in liquid ammonia, magnesium does not dissolve in liquid ammonia on long heating but on long heating hydrogen gas evolves, long heating hydrogen gas evolves, that is it. So after the break, we'll start with oxides and few properties of oxides, oxides, hydroxides, carbonates, carbides. These compounds will see. So we'll finish off all these things today itself. After this, we'll have a few things on left. No, we'll see that also later on. Okay, fine. So we'll take a break now. We have done a lot of things. That's why I'm taking a break a bit early. We'll resume at 620.