Compare some of the physical properties of H₂S, NaH, and PdH_x.

Video transcript

All right. Hi, everyone. So this question is asking us to describe the physical properties of the following substances. P three, cah two and zrh 1.9. So the first thing that I want to point out here, right is that the three substances listed happen to be binary hydris. And the reason for this is because there are two types of atoms present in this molecule or rather each molecule and one of them happens to be hydride, hence or hydrogen, hence the word hydride. So let's go ahead and get started with the first binary hydride, which is ph three. Now in the compound ph three, we're going to see a bond between phosphorus and hydrogen in this molecule. Now phosphorus is a non metal, right? And so is hydrogen. So recall that when we talk about two nonmetals combining together, that process is done via a covalent bond, right? Because two non metals are capable of sharing electrons in between them. Therefore, right, because phosphorus and hydrogen are both metals, this is or non metals. Sorry, this is a covalent hydride. There will be a covalent bond between phosphorus and hydrogen. So here, right? Ph three is a covalent hydride and it's a covalent hydride in which molecules are held together by relatively weak intermolecular forces, which means that ph three is neutral and it also exists as a gas in room temperature or at room temperature. And the reason for this is that when intermolecular forces are relatively weak molecules are more spread out, right? They're able to travel more away from each other. So now let's proceed with cah two. Now C A which is calcium, right is a metal, whereas hydrogen is a non metal. Now recall that when a metal and nonmetal interact together that tends to form ionic bonds, right? And the reason for this is because the difference in electronegativity between a metal and a non metal is large enough so that electrons are transferred as opposed to shared in between them. So because calcium and hydrogen are going to use an ionic bond to interact with each other. Ch two is going to be an ionic hydride. And if Cah two is an ionic hydride, then these ions are being held together by very strong electrostatic forces, right? Because there's going to be a very strong interaction or attraction between the cion and anion, which means it's CH two is going to be a solid at room temperature with a high melting point because more energy would be required to break those strong intermolecular forces. And up next is zrh 1.9. Now, the first thing I want to point out about zrh 1.9 is that this compound is actually non sto geometric. And the reason I can tell is because whole numbers are not being used to describe the ratio between zirconium and hydrogen. Because here we're seeing a 1 to 1.9 ratio of zirconium to hydrogen as opposed to a 1 to 1 ratio or perhaps a 1 to 2 ratio. So here, not only is this a non stoichiometry compound, it's a compound in which a transition metal zirconium is interacting with a nonmetal like hydrogen. Now recall that when a transition metal interacts with the non metal in a non stoichiometry ratio, meaning not a whole number ratio. This is going to be characteristic of a metallic hydride. Now, metallic hydride are also known as interstitial hydride because in the crystal lattice structure of zirconium, the smaller holes in between the atoms in the crystal lattice are occupied by hydrogen. Hence the term interstitial no metal hydride retain or metallic hydride retain their metallic properties in the sense that they're going to generally be solid at room temperature and there you have it. So Ph three is a covalent hydride which exists as a gas at room temperature. Ch two is an ionic hydride that exists as a solid at room temperature. And zrh 1.9 is a metallic or interstitial hydride that also exists as a solid at room temperature. So with that being said, thank you. So very much for watching. And I hope you found this helpful.