MGM Chemistry 1 Nuclear Chemistry
Sep 3, 2008
All right guys, today we're gonna talk a little bit about nuclear chemistry. First of all, we need to talk a little bit about what nuclear chemistry is and how it's different from regular chemistry. And we're gonna make a couple changes. First of all, change the top of this. This should be chemical on this side. And the second column we're going to talk about is nuclear. So just a mono typo there, and let's talk about chemical nuclear reactions. All right, chemical reactions. Chemical reactions occur when bonds are broken. And when bonds are formed. So what happens in a chemical reaction is bonds get broken, they kind of get scrambled altogether all the atoms get scrambled together and then they rearrange and form in different combinations than what they started with. Now this is different from a nuclear reaction. In a nuclear reaction, the nucleus actually spits out particles and rays and or right. So think of a nuclear reaction that that nucleus being a big radiation gun and it just shoots particles and rays out of it. All right, and you have a chemical reaction. The atom remain unchanged. But they're just going to be rearranged. Again, if you start with carbon hydrogen and oxygen, you're going to end with carbon hydrogen and oxygen. It just may be arranged in link to different chemicals than they started with. With the chemicals you start with or the atoms you start with are going to be the same atoms that you end with. Now, this is different than in a nuclear reaction. And a nuclear reaction, the atoms are not the same as what you start with. You're going to end up getting a completely different element than what you started with. So items of one element are actually converted into another element. So what you start with is not the same element that you end up with. In a chemical reaction, it involves only what we call the valence electrons. And the valence electrons are the electrons on the outermost shell of the atom. They're the electrons on the very outside of the atom. This is different from nuclear reactions. Nuclear reactions get involved, protons, they can involve neutrons, or they can involve any of the electrons that doesn't just have to be valence electrons. So nuclear can involve any of those subatomic particles. All right, came up for reactions have very small energy changes. When you compare them to nuclear reactions, which have very large energy changes. And the last thing are going to be reaction rates. Reaction rates are how fast your reaction progresses. Now, in a chemical reaction, I can speed a reaction up or I can slow reaction down. I can do that by changing the temperature, I can change the pressure, I can add something called a catalyst. Or I can even change the concentration. Okay, so I can make a reaction go faster or slower if it's a chemical reaction. If it's a nuclear reaction, the right constant doesn't matter how much I heat it up or cool it down, I can't change that rate. Sorry, I can sell there for a minute. So it doesn't matter how much I change the temperature, the pressure or having catalyst or concentration. And nuclear reactions is just going to go to the speed it's going to go. There's nothing you can do to slow it down or just speed up that reaction. All right. The reason that nuclear reactions happen are these nuclei are these nucleus. The nucleus is very unstable. Only around 7% of elements or isotopes are stable, everything else is going to decay into something else. So you have all this kind of radiation going around you all the time. That process of going from something that's unstable to something in its stable is called radioactive decay. All right, we're radioactive decay process. Now, there are three main types of radiation that we're going to talk about. There are more than three times, but we're going to talk about the main three. And those are alpha. Beta and gamma radiation. Now, some of our alpha is that funny looking, looks like a little goldfish. That's actually the Greek letter for alpha. It looks like a funny little goal. There's there. They did that cursive looking beat. And gamma is a funny looking wine. All right? Now, we have a little chart here, and we're going to kind of make our own chart at the end. And that's a different properties of alpha beta in gamma radiation, but here's a nice little synopsis from all the different things we're going to talk about. First one we're going to talk about is alpha radiation. Now, alpha, begin a little symbol, it's like a little goldfish there. Has the same composition as a helium, nucleus. Okay. And again, it's the helium nucleus. Don't forget what's in the nucleus. The nucleus only contains protons and neutrons. There are no electrons in the nucleus. So if we have a helium nucleus, he laying contains two protons and two neutrons. So our symbol for alpha is going to be four, over two, HE. So whenever we run a nuclear reaction, we're going to write for every two HE, or alpha. Now, let's talk about the charge of alpha. We said it had two protons and two neutrons. Again, no electrons because it's just the helium nucleus. We have two protons. That's two positive charges. And two neutrons is two neutrons. So 5 two positives into neutral, that's going to give me a total charge of positive two. So the charge of alpha is positive two. Now, let's talk about how to block alpha. What'd you think of alpha is like a big, slow moving beach ball? Compared to beta and gamma alpha is very big. And it doesn't have a lot of energy compared to the other two. It's much more slower moving. And there's a lot more slightly and it's just kind of big and cumbersome. When you compare it with the other ones. Now, they aren't very penetrating at all. We're going to talk about what blocks them. So imagine I had a big radiation done here. And I start shooting alpha particles at you. And you are on the other end and you don't want me to teach you with alpha particles. All you have to do is solve the piece of paper. Paper blocks alpha particles. So paper, it's going to block alpha particles. So if you just type in front of you, you're going to be happy, happy, happy, and alpha particle freeze. So these papers are going to block alpha particles. Now let's talk a little bit about beta. Beta particles are just a fast moving electron. So betas are much more higher, much higher energy than alpha particles are. It's a fast moving electron. Now, because it's going to electron, we're going to represent beta by using zero, negative one, B now that negative one is there because electrons are negative. So we need to denote that negative charge. Again, we said beta radiation is fast, moving, electron. Now these electrons are much, much smaller than helium nucleus. They're teeny teeny tiny when you compare them to alpha particles. They're also much faster, and they have a lot more energy. So let's talk about what's going to block by them. If I have that little radiation done here, and this time I change it from alpha particles to beta particles, and you are on the end, and you hold up a piece of paper, it is not going to help you. It's going to go right through and you're not going to be happy at all. To block theta particles, you need a piece of metal oil. Sunflower to metal floor like Reynolds round. Beta particles can not get through that metal ball. So if you want to save yourself from beta verticals, just wrap yourself in Reynolds wrap. So we need some sort of metal boil to block data particles. Now, let's talk about gamma. Alpha and beta are particles, alpha is a helium nucleus. It consists of tangible particles. Beta is a particle. It's a fast moving electron. Gamma is not a particle. Gana is just energy. So it's lots and lots of energy. It's just a high energy radiation. The symbol for gamma because it doesn't consist of any particles, it's going to be zero over zero with that funny looking Y and again, because we have a zero over zero. It's not going to change anything. You're not going to change the top number. You're not going to change the bottom number. These zeros are nothing but energy. No particles are going to be changed in this. Now, gamma radiation doesn't usually occur by itself. It usually accompanies alpha or beta radiation. So it kind of tags along with those guys. And again, let's talk about our little particle gun right here. So that's a little particle down. This time, that's an alpha. This time we're going to see gamma oracles at ya. You hold up a piece of paper, you are going to have a bad time. It's going to go right through it. Remember, gamma has a lot more energy than alpha does. Now, let's say you're drawing the good old rental frat. The wrap yourself in Reynolds. You are still going to have a bad time. Game of particles are going to go right through. The only way to slow down gamma particles in any way is to use a big piece of lead. Lead will block most of those gamma particles. If you want to block gamma or again, not game of particles, gamma radiation. I'm sorry about that. If you want to block that gamma radiation, you need to hold up some lead. And again, gamma is not a particle can that's just a high energy radiation. Lots of energy and gamma. Now let's talk about the flexion. Deflection means you're going to alter the trajectory of where these particles and radiation are going to go. Okay? So let's say you've got this electric field. So I again, and we're going to imagine this is my little radiation done here. And I'm going to shoot out an alpha particle into this little slot. Now, I have, let's say I have a positive light here. And I have a negative point here. And first thing I shoot out of this little gun is now for particle. Where is it going to go? Is it going to go up? Is it going to go down? Or is it going to go straight? All right. Alpha particles are positive. They actually have a positive two charge. And you should know that opposites attract and like charges repel. So it's not going to go up because the top plate is positive. That would be a positive and a positive. There's things on the track. The positive alpha particle is going to be attracted to the negative plate for the alpha particle. It's actually going to be deflected toward the negative plate. And in this game, it's going to go down. So the positively charged alpha particle, it's going to be deflected toward the negatively charged plate. All right. Let's talk about data particles here. So this time I'm shooting a beta particle through. And again, I have a positive plate. And I have a negative flight. All we know that light charges attract. So beta is going to be attracted to the positive point. And if you look at the distance between the center and beta and the center and alpha, beta is actually deflected more so Veda is going to be more deflected because it's smaller. So it's going to have that positive plate is going to have more of a pull on that electron because it's much, much smaller than the other one. So the negatively charged beta particles are going to be attracted to the positive light because the opposite to drag. All right. And again, that's next slide beta particles and they're going to greater deflection because they are smaller than those alpha particles. Much smaller so the deflection is going to be more. Last one is gamma ray. So let's say we're shooting gamma out. Well, gamma wasn't positive, and it wasn't negative. So gamma is going to go straight across. There's going to be no deflections. So gamma charges or gamma radiation is not deflected. Okay? Not going to be deflected towards positive or the negative. It's going to go straight across. All right, let's make a little chart here. I said we were going to make a chore. If I can, there we go. Let's make a little chalk here. We're going to talk about the name of the radiation. We're going to talk about the shorthand way. To denote that type of radiation. We're going to talk about the symbol. All right. We're going to talk about how you can block it. How you can deflect it. Again, this is just a synopsis of everything we've done so far. We're going to talk about its energy. And we are going to talk about its makeup. Okay, or what it is. All right, we got alpha. Beta. And we've got gamma. All right. Shorthand way to write alpha look like a little goldfish. A symbol for alpha was four over two, HE. How could you block alpha particles if I was shooting at them? Shooting. Shooting me with them. You could block it by paper. Now, oh, let's add the charge. We'll add a little symbol here for charge. The CH is going to be drawn. Charge of an alpha particle was positive two. How did we deflect it? Or which way was it going to get deflected? It was deflected for the negative plate. Now the energy is small. When you compare it with the others. And the makeup was a helium nucleus. Remember no electrons in alpha. Beta sort and verbatim, the low cursive B it's charges negative one. The symbol is zero over negative one, B it's not deflected by type or it's not stopped by paper. It's going to go right through that paper. You need some sort of metal hole to stop beta barnacles. It's negative one. So it's going to be deflected toward the positive flight. It's energy is we're going to call it medium. It's higher than alpha, but it's lower than gamma. And the makeup is a fast moving electron. Last one, gamma, but in like a Y no charge for VMware. It's not positive or negative. The symbol is zero zero gamma. Block by lead. No deflection. Gamma, energy is high. Compared to the others. And gamma is just high. Energy, radiation. No particles on gamma is high energy radiation. All right, watch periodic table because we're going to write some nuclear reactions here. Now, whenever you write nuclear reactions, you need to remember the law of conservation of matter. Which was matter can't be created in order to destroy that. The miss Lagrange way to say that was the stuff you start with has to equal the stuff that you end with. Now, the other thing you have to be able to do to do nuclear reaction is to do what we did yesterday was to write the formulas for isotope, and don't forget to write an isotope formula. Mass number goes on top. Atomic number goes on the bottom and the symbol for the element goes to the right of that. All right, watch periodic table. Now let's write some nuclear reactions. First what we're going to do is write the reaction for radium two 26 converting into right on two 22 that should be a dash there and a dash there. All right, first of all, we need to write what we have going on. We're doing the reaction for radium two 26. Let's do the symbol for radium two 26. Look up your periodic table and you'll look up radium and you'll see radium is R a and we know it's radium two 26. That's your mass number. So two 26 is going to go at the top. And if you're at the bottom number, look up radium on the periodic table. I'm RA and it should be number 88. So we've written writing two 26, converting into, what do we draw when it says converting into? But after converting into, that means you draw an error. Now it's converting into right on two 22. So let's write it in the formula for write on two 22. Look at your periodic table and you're going to see that right on is R in. And it's right on two 22 in the math number, so that goes at the top. So two 22. Look up RN and you'll find that RN is actually number 86. All right. We had to do the log cons of race to mass here, which means what you start with has to equal what's in with. And we're going to be giving off some sort of radiation. We have to do that. We're going to write a more given off. Now, this little arrow, I want you to imagine it's an equal sign. So let's look at the top numbers. Two 26 needs to equal two 22 plus something. You shouldn't need your calculator for this. Two 22 plus four equals two 26. So we know the top number needs to be four. And let's do the bottom numbers. 88 equals 86 plus something. That's something is two, and if you have a four over two, that is HE. So alpha particles were actually given off here. But this type of radiation works out radiation. All right, let's try another one of these. Right the reaction of carbon 14, turning into nitrogen 14. All right, let's write these forms out. Carbon 14 no carbon is D and I know it's carbon 14, so that goes on the top. Now I need the bottom number. I'll get your periodic table and carbon is number 6. No. Decaying into that word into, so we need an error. Now we need to draw our right nitrogen 14 nitrogen is in. And it's nitrogen 14, so 14 is going to go at the top. And look at your periodic table. 7 is going to go at the bottom. Yep. It's going to give something else off to. What you start with has to equal which end is. So we're going to put a little equal sign here, 14 equals 14 plus, should be a zero. Bottom is 6 equals 7 plus one, 7 plus one is 8, 7 plus negative one is 6. So if you have a zero over negative one, that is beta. So this reaction actually gives off beta radiation. All right, the standard one more of these. We're going to write uranium two 38 undergoing alpha and gamma decay. All right, your right name two 38. So I know you're writing as you and I know it's two 38. So we put that on the top. You look up your writing on the periodic table, look down at the bottom, actually number 92. So it's undergoing, so we're going to draw our arrow. Alpha and gamma. So the first thing I need to write is an alpha particle. You should know that alpha is four over two, 80. That's taken care of alpha. Now I need to take care of the gamma. Gamma is zero, over zero, let me look them on. That's what gamma is. That's going to give off something else. We got to figure out what that something else is. And our little equals on. Two 38 equals four plus zero plus something. That top member needs to be 234. All right, bottom numbers. 92 equals two plus zero plus at bottom number should be 90. To get the letters, you just look up 90 on your periodic table and you should get TH. So this is your entire reaction right there. These are easy, easy, as long as you remember the law of conservation of matter, and you can write that formulas for isotopes. A couple more definitions and we are done. It needs to talk a little bit about half life. That flag is exactly what it sounds like. It's how much time you need, for half of your isotope to the K, okay? You're so half life is going to be in units of central to time. Seconds or days or hours or years, but how about this how long it takes for half of what you start with to decay. So let's say you have a hundred grams of some isotope is radioactive. I want to know how much is left after one half life, okay? We're not going to do any math for them this year. You're going to start with a hundred grains. You're going to go one, half on it. Well, half life is how long it takes for half of it to decay. So if you went one half life, you'd have half of what you started, which is 50 frames, some easy, easy, easy peasy. All right, let's do this one. How much is left after? Two half 5. You start with a hundred grams, you go one half line, and you've got 50 grams left. But I didn't want to have I wanted to. So you go another half life. Here are your second half line. And you have 25 grams left. I have black problems or the caliber. We're going to be doing right now or easy easy. We'll get into some formulas and some more difficult calculations for them later. A couple definitions. First one is vision. All right. When you think of the word vision, I want you to think of the word biz. It's actually taken the nucleus and splitting it into whole bunch of fragments. Now, when you have a fission reaction, they release tons and tons of energy. So you get lots of energy out of a fission reaction. It actually, this is what nuclear power plants use to generate power. They use fission reactions. So you get a lot of energy out of the fission reaction. I'll talk about fusion reaction. Fusion reaction is just what it says. You're using more than one nucleus together. So think of think of it as kind of melding them all together. They're fusing together. Now, these release tons of energy, much more energy than vision reaction one. So you get more energy and a fusion than you get out of fission. You may say, well, get more energy adhesion and vision, then why aren't we doing fusion reaction in the power plants instead of fission reaction? And the reason is that fusion reactions require extremely high temperatures in order to occur. The lowest temperature that you can have a fusion reaction at is 40 million Kelvin, okay? So that's really, really, really hot. So the reason we don't need Asian reactions is because I imagine if you had a building and you were trying to get it up to 40 million gentlemen, everything in that entire building would just melt. There's no way you could get there. And actually the only flight that we know fusion reactions is hiring right now are on the sun. That's it for this podcast. If you have any questions, please come see me.