Intermolecular Forces and Trends, Formal Charges, Hund's Rule, Lattice Structures and Unit Cells

After they say what cell it is, you can tell it instantly, oh, yes I know. it's a stupid simple cubic so I know there's an atom and I know the edge length is going to be this formula so that's what's going to be really beneficial so let's ask a question so this is going to be finding the molar mass. Let's say if we had something like this where we have a metal crystallized in a face-centered cubic structure, then at that very moment it tells us what it is, that will give us a lot of information, like the formulas that we are going to use. use and then it also says that it has a density of eleven point nine grams per cubic centimeter if the radius of the metal is 138 picometers what is the molar mass of the metal, so I know very well here the molar mass of the metal, that's what we are Trying to find out with all this information provided, there are a series of steps that we will have to follow to get there.

Okay, so first we identified what the face-centered cubic cell means, how many atoms per cell there are, and what the length of our edge is, so from that chart that we thought we talked about earlier, this is going to be extremely beneficial because it's going to help us To know what formula we will need to use, since we are looking for the molar mass. The fact that they gave us the density will be our most important clue, so our game plan here will be to start from the radius that was initially given, so I know that I already know that it is 138 Pico meters. this is in centimeters so I don't want picometers.

I want to convert it, so that will be my first step: just convert picometers to centimeters using the metric system and then remember that we can't instantly jump from there. Peak meter to centimeter there has to be something in the middle, so our meters are going to be that kind of center that we're going to have to make, so I'm going to set that up and then set this up one more time. I'm going to start with my radio. I'm just converting that radius so 138 picometers for every 1 picometer there's 10 to the negative 12 meters that would cancel out now that we're in meters and then I know there's for every 1 centimeter there's 10 to the negative second meters and that would cancel out. and now this gives me this number of centimeters so now that we have the correct centimeters what I'm going to do next is find what L is all true, because I know what R is, so this is our formula that we're going to use and that was just the fact that I knew it because I was told it's a face-centered cubic structure, so now that I know what R is and it's in the right

unit

, this is our art, I'm just going to plug it in, so I'll just plug it in, so I'm plugging in the here, it's going to be twice this value and then multiplied by our square root of 2, that's going to give let's use this value, so now I know what L is, which is great, but remember I'm looking for my mass. and what will allow us to get to our mass is the fact that it's in grams, the density is in grams, so since I have centimeters right now what I have to do is find the volume because remember density is density is mass divided by bullying, so what I have to do is cube the edge length or L to find our volume, so when I do that now that I have the proper

unit

, so now I have the proper unit of centimeters cubic and then what I'm going to continue to do is since I have the volume, now I can plug it into the density formula and find the mass, so I know what the density is, okay, they gave us that and I'm just going to plug it all in. what I know, so this is what I found for the volume, this is what they gave us initially for our density and then I go from there.

I'm just going to multiply both sides by this value and then from there, once I do that, the centimeters and the centimeters, the cubic centimeters would cancel out and we would be left with our grams, so the other thing we have to continue doing is that we are looking at. not just the mass, we're looking for the molar mass, remember molar mass its units are grams per mole, so we find the grams, we find what's on top, so check that's out of the way, then we have to find how many moles there are in this face centered cube or cubic

structures

, so what I know is that there are 4 atoms, that's where this will come from.

The fact that I know there are 4 atoms, well, Adams goes with Avogadro's number, so I'm going to use the average number of rows. put it here so they can line up and then cancel for each mole because I'm trying to get two moles so I knew I had to do this because I wanted the molar mass. We said that molar mass was grams divided by moles. I needed moles now, so that allows me to get two moles. I know I have to somehow connect the atoms to the moles. The connection factor or the conversion factor that allows us to go from atoms to moles is then Avogadro's number, that's how I know how to divide. that and then get the moles the last step is just dividing those two to divide our grams and our moles and we get our molar mass of the metal so I know these questions tend to be long but like I said if you know that table of the one we talked about initially, that will help you a lot because it already gives you the formula to start with and then just as a note, you'll usually always be given this in a different unit. the radius and a different unit, whether picometers or something else.

Normally I see picometers, but you most likely have to convert that from the beginning, so be careful, the way I needed to convert was just the fact that the density was in centimeters and not pico meters, so the color Rosa said that was the main thing we were seeing. I'm watching everyone, let me see how everyone else is doing, perfect. I think everyone had some different questions that they were asking, be sure to watch a lot of the videos that I have because now I have an almost complete summary of what you guys need. I added many more videos, including some of my past lives.

I went over a lot of different topics that I had before, so if I talked a little bit about, you know, enthalpy and enthalpy of formation, standard enthalpy of formation. I have a video on that, so several different things, so make sure you watch the videos that I already have and then if Bobby If you didn't cover a lot of

structures

in a semester, don't worry, it really depends on the curriculum. Sometimes I see this is more for a general chemistry class in college, it was when I took it personally or when I've seen my students use it, so don't worry about that, if you haven't covered it, be thankful that now this is the last concert of the year.

Oh my goodness, to everyone who is joining today or has been here for several lifetimes, thank you. So much for being here, I enjoy doing these concerts and I enjoy teaching you guys, that's always a really fun thing to do, so be sure to check out the other videos I'll be posting soon and see if I've helped you in any way this semester. and you would like to help me, support me and on this channel of course I would love to and we really appreciate that I have a patreon page that I finally selected so if you want to support me with Patriot with my patreon page.

I just put it in the chat and it's also in the description in a box of this video, so like I said, if you feel like that's what you'd like to do, of course, if not, I completely understand, so many Seriously thanks. Guys, being here, another thing I wanted to mention is if you have more, if you need more help, whether it's with chemistry or if you continue with chemistry or if you're just taking other math classes, physics classes, biology classes. classes and if you still need additional help, I know I don't technically teach that, but I recommend a source called check Study that personally helped me with many different topics and all the different classes that I was struggling with.

It helped me understand my homework, which is essential because they were practice problems, so it was really nice to try it out and see where I went wrong and where I need to improve, so checking study is a great way to see where you are. I need to improve because it gives you that step by step solution so you can see. Oh, I forgot that step. I need to do it next time so I personally really liked it, so amazing guys, thank you so much for being here. I hope you have an amazing week, kill your finals guys, work hard.

I know you can do this and I have plenty of videos for you to watch if you need them and of course as mentioned if you need more. help there are links in the description for that and there are also notes that are currently on sale for 40% off all my notes ending today so that's the final sale so be sure to check it out if you need any additional help and want to delete. Your study time was cut in half because I know it's time to play, okay guys, so everyone says thanks, you're welcome. Oh, and I forgot to mention that everyone who is taking Brittany just reminded me that they will be taking ochem next year, perfect.

I have a second channel, so a lot of people don't know, but I have a second channel on organic chemistry, so if you continue or eventually are going to continue with organic chemistry, I have you covered, so don't worry. that's what I'll be covering or I have several videos about someone who just asked a question about the name. I have several videos on organic chemistry. I'm adding more and I know how to name alkanes which will help the person who just put a name in there so I have or actually was an alkene but I have several videos on that so be sure to check it out and yeah a lot Thank you once again for being here, have an amazing week and I hope to see you too. next semester or else, good luck guys with whatever you decide to do, okay guys, see you