 All right, welcome back everybody. We are going to do a different kind of decay now. This is uranium atom. So in particular, this isotope of uranium is uranium 238. Hopefully you'll appreciate that this was a giant pain in the ass to draw on the computer. And again, I'm going to tell you that uranium 238 is also unstable. What I mean by that is if you wait around long enough, it's going to turn into something else. I don't expect you to be able to look at this and say, oh, that's definitely unstable. I'm just telling you that it is. There's going to be another amazing animation. You should probably focus your attention somewhere around there. So if you wait around long enough, this is what happens to uranium 238. Let's watch that again. So what got fired off? Well, it's two protons plus two neutrons got fired off into the distance. If you look up in the periodic table, what type of atom has two protons? Well, it's a helium. So to fill in this part of the decay equation, uranium 238 is going to fire off a helium. But not just any old helium. It's a helium that has a mass number of four because two protons and two neutrons got fired off. So we're going to put a four there. If we want, we can put a two in the lower left because the stuff that got fired off has two positive charges. That might be helpful later. If you notice, there are no electrons that got fired off here. So this particular isotope of helium also has a charge of two plus because it has two positive charges and no electrons to cancel out those charges. And we can, all right, I'm going to fire it off again. Everybody be amazed again. It's gone. Now the uranium 238 decays into something else, right? This is not uranium anymore. And so the question is to figure out what it is that uranium 238 decayed into. We can play the same game as we did in the previous video. The total weight of everything on the left side is 238. So the total weight of everything on the right side has to add up to 238. This time, the helium that got fired off weighs four. So the question mark has to weigh or have a mass number of 234 because 234 plus four gives us 238. We're almost done. We have to figure out how many protons or how many positive charges uranium has. You can look that up in the periodic table. That's going to be 92 if you look that up. And so we say, all right, there are 92 positive charges on the left side of the arrow. We have to add up to 92 positive charges on the right side. The helium took two of the positive charges. So the question mark has to have 90 because 90 plus two gets us to 92. And remember, it's only this bottom left number that tells you what kind of atom you have. Nothing else tells you what kind of atom you have. If you look up who has 90 positive charges in the periodic table, you'll see that it's a type of atom called thorium. And the abbreviation for thorium is capital T in a lower case H. This is just another type of decay equation. Uranium 238 decays into thorium 234. And it fires off a helium isotope that weighs four AMU or has a mass number of four. This is the kind of decay that they found first. So this type of decay is called alpha decay. Again, I don't really care that you know these names, but they do show up in your book. I'm not going to quiz you on the names. I'm going to do this type of thing on a quiz or a test. I'm going to hide one of the pieces in the decay equation and ask you to figure out what it's made of. You can practice on this one. This is a polonium 208. This is enough of the periodic table to figure this out. You can pause the video and think about this. On pausing the video, well, everything on the left side of the arrow is 208. So everything on the right side has to add up to a weight of 208. The helium took four of the weight, if you want to think of it that way. So the question mark has to have a weight or a mass number of 204. Polonium has 84 positive charges or 84 protons. So I'm going to write an 84 there just to make my life a little easier. So everything on the left side has a total of 84 positive charges. We have to add up to 84 positive charges on the right side. The helium took two of them. So whatever the question mark is, it has to have 82 positive charges. If you look up who's got 82 positive charges in the periodic table, you'll see that it's lead and lead has a little bit of a weird symbol. It's a capital P, a lower case B. And so there you go. That's just another example of alpha decay. But if you notice, the rules are the same no matter what kind of decay you have. Top numbers have to add up to the same number on the left and right. Bottom numbers have to add up to the same number on the left and right. Doesn't matter what kind of decay you have. And again, I kind of think of this as like balancing an equation, but hopefully you'll agree that it's easier. All right, that is the end of this video. See you in the next one. I don't know, but I've been told you're any mores worth more than gold. So, Macad, I bought me a Jeep. I got that bug and I can't sleep. Uranium fever has gone and got me down. Uranium fever has spreadin' all around with a Geiger counter in my hand. I'm going not to stake me some government land. Uranium fever has gone and got me down.