Now, here, we're going to say that alpha decay occurs when an unstable nucleus emits an alpha particle. Now what exactly is an alpha particle? Well, an alpha particle consists of two protons and two neutrons. So let's think about this. If it's two protons, that means that its atomic number would be two. And remember for your mass number that comes from adding together your number of protons and neutrons together. That's why we have four here and four here. If you look on the periodic table, you'd see that the element has an atomic number of two is helium. So here we're dealing with helium, but we just did that. It's an alpha particle. So you can also represent it with the alpha symbol. So an alpha particle can be represented by helium four or by the alpha symbol. Here, we're going to say this typically occurs in heavy nuclei with excess protons and neutrons. Later on, we'll classify what exactly constitutes a heavy nucleus. Now, here it produces a stable helium atom which is in this case, helium four isotope. Now, when balancing nuclear reactions of any type of radioactivity, um we must always balance the atomic number, which is the number of protons as well as the mass number, which remembers the number of protons and neutrons together and they have to be balanced on both sides. If we take a look here, we have our basically our parent nuclide which is uh platinum, platinum 171 it's going to decay or break down and produce an alpha particle. Remember, we need to have make sure that the overall mass number on both sides are equal and the overall number of protons on both sides are equal. Here on the reactant side, we have 171. Our alpha particle gives us four. The product site still needs to add up to 171 though. So we think about it. What number would I place here that would add with four and give me 171. Well, 167. So our new isotope that we're making has a mass number of 167. Let's look at the reaction side. Our parent is 78 are alpha particles already giving us two. But remember the total number of protons have to be the same on both sides. If your alpha particles given us two already, what number do I have to place here in order to get 78 at the end 76? Remember your atomic number, the number of protons is unique to the element. So look on the periodic table. What's the only element on the, on the periodic table that has an atomic number of 76. So here that would be osmium. So here we say that our platinum 171 isotope undergoes alpha decay to produce osmium 167 plus an alpha particle. Osmium is a pretty um interesting metal. When it comes to the periodic table, it's one of the most dense elements on the periodic table. Uh So that's just some extra information. It's not really important to this question to get the answer. Just want to give you guys that piece of trivia. All right. So here we've just shown an alpha decay for our first isotope and this is the way you have to do it. You have to make sure that your mass number has to be the same on both sides. On the reactive side. It's 171. So it needs to add up to 171 on the product side. The total number of protons is 78 on the reactant side. So you have to add these together to get 78 again. OK. So make sure the number of protons and mass numbers are the same on both sides of your nuclear reaction. That's how we balance them.
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example
Alpha Decay Example
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Here, it says to write a balanced nuclear reaction for the alpha decay of radium 204. All right. So here we're undergoing alpha decay. So we have radium 204 alpha decay means that we're going to produce an alpha particle which is 4/2 alpha symbol or helium. Now remember the mass numbers on both sides have to equal the number of protons on both sides have to equal, we have 204 on the reactant side. So on your product side, it needs to also add up to 204, we already have four coming from the alpha particle. So we need an additional 200. So 200 plus four gives me +204. On the product side, on the reactant side, we have 88 protons with radium. We need 88 protons on the product side, two of them already coming from the alpha particle. So to get to 88 our new one told us to have 8686 plus two, gives me 88 look on the periodic table and that would be radon RN. So this would represent the alpha decay of radium 204. It produces an alpha particle and our new isotope of radon 200. OK. So this would be our final answer.
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Characteristics of Alpha Particles
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Now, when it comes to our energetic particles, we have to talk about their ionizing power and their penetrating power. Now, ionizing power is the ability of an energetic particle to it's in the name ionize atoms and molecules penetrating power is the ability of an energetic particle to pass through matter. Now, with these energetic particles, it's important that we shield ourselves from their effects because if they can get into our bodies, they start ionizing molecules and atoms inside of us, it can lead to some very dangerous and disastrous results. So here, if we're talking about the alpha particle, let's talk about its particle symbol and we know that it is 42. And then the alpha symbol or the helium symbol. Here we have basically our alpha decay reaction which is the platinum 171 isotope decomposing to give us osmium 167. In terms of size, we say that the alpha particle is the largest of our energetic particles because it is the largest, its ionizing power is the highest. Now, luckily because it's so large, it's hard for it to penetrate our skin. So we're gonna say that it has the lowest penetrating power. Now what can shield us from the effects of an alpha particle? Well, because they're so large, it's easy to stop them in their place. They can't get through uh nooks and crannies and crevices because they're so large. So things such as clothing can protect us from an alpha particle. Our skin, our skin is strong enough and, and thick enough and the alpha particle being so large, it can't penetrate our skin. We can also say paper, even the air around us can act as a shield against alpha part. Now, you're going to say because of high ionizing power, alpha particles are considered the most damaging to biological tissues. Remember they're very large. So because they're large, they're, they're gonna move very slowly if they get into our system, giving them ample time to ionize everything around them in terms of our biological tissue. So it's always imperative to make sure that something like this does not into our bodies. How could it into us? Well, maybe alpha particles you're in a nuclear facility or something and alpha particles contaminate your food and you ingest, it can't protect yourself from that. Once you, it will consume the food and it's inside of you, then again, it can lead to very daft like dangerous and disastrous results, right? So just keep in mind these fundamental ideas when it comes to the alpha particle, in terms of its ionizing power and penetrating power
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example
Alpha Decay Example
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Here it says, select the correct statement by alpha decay. Here, the parent nuclide gains two protons and two neutrons. No, it doesn't gain them, it loses them to create the alpha particle produces radiation by absorbing a helium nucleus. No, it doesn't absorb the helium nucleus. It emits or gives off or loses the helium nucleus. That's what the alpha particle is. Alpha particles can easily penetrate cells. Well, in terms of size, the alpha particles are the largest. So it's hard for them to penetrate our skin and therefore penetrate cells as easily. When alpha part, when alpha decay occurs in an unstable atom, the mass number decreases by four and the atomic number decreases by two. This is true because what are we losing? We're losing two protons and two neutrons, two protons being lost would lead to a decrease of our atomic number by two and losing two protons and two neutrons would give us a mass number of four. So your mass number would decrease by four. So here option D is a true statement.
