 Okay, so the continuation of that problem when molybdenum crystallizes, it forms body centered cubic cells. The unit cell edge is 314.1 picometers. Calculate the density of molybdenum. Okay, so now, remember in these density problems, we're going to have to find the number of lattice points per unit set. Okay, so that in this case is Z. Okay, number of lattice points for a body centered is just very similar to the simple cubic, right? Where you have one atom on each of the points there. So it's going to be eight times one divided by eight. But you have to add that one, the full atom that's inside the unit cell. When you do that, you get one plus one. So that's the first step of doing this. It also, well, let's write the formula down. So density equals Z times molar mass divided by side cubed times avogadro's number. Okay, so we know Z is two molar mass. What did I say it was? 95.994 grams per one. The side, remember, we want these densities in units of, it didn't say, but grams per cubic centimeter, okay? So it gives us the side in picometers 314.1 picometers. So how many centimeters is that going to be? Times 10 to the negative eight, seven. So it's a good one to remember because you're going to have to do this calculation a lot. Now, how did I do that, right? It was one times 10 to the 10 picometers per one, seven. And then avogadro's number, of course, that'll probably be given to you. But 6.022 times 10 to the 23rd, anything, in this case, atoms per mole. So now we'll chug, right? So Z, vanish units is two, all our mass, 95.94 grams per one mole divided by 3.141. It's got to be something in everybody, you know? Times 10 to the negative eight, 5.022 times 10 to the 23rd, divided by one mole, like that. Cancel, cancel, grams per cubic centimeter, all right? Okay, so 466, so I get 10.28 as the density of, what are we doing, we'll look to know. Is everybody okay with that one? Same answer, hopefully. Questions, questions? We could probably do these all day, all right? Okay, good.