An alpha decay or alpha emission occurs when an unstable nucleus ejects an alpha particle to create a new element.
Understanding Alpha Decay
An alpha particle is comprised of 2 protons and 2 neutrons.
Alpha Decay Concept 1
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Hey, guys, In this new video, we're gonna take a look at Alfa Decay. So remember, Rutherford talked about the three major types off decays. There's Alfa decay, beta decay and gamma emission. Here we have Alfa Decay. We're gonna say alpha decay occurs when an unstable nucleus emits a particle composed of two protons and two neutrons. Now, just think about it. We say that our atomic mass equals the number of protons, plus the number of neutrons. So here are atomic masses. We lose two protons and two neutrons, so two plus two gives me four. Your atomic mass is protons and neutrons added, and your atomic number is just the number of protons, so the number of protons losses too. So we're gonna say the Alfa particle is represented by four for your atomic mass over to your atomic number. And here we have our Alfa symbol. Now, we can also say that on our periodic table we have an element that also has on atomic mass of four and an atomic number of two. That element is helium. So we can say that the alpha particle can also be represented by the element helium because helium has the same atomic mass as an Alfa particle and has the same atomic number as an Alfa particle. And remember, we're using the term decay. So the K means that this alpha particle will be, ah, product. So if we wanted to look at an example of this, we could think of, for example, on your periodic table, you could have polonium. When John, your periodic table is p o palladium, we're gonna say, Let's talk about isotope to 10 Now remember what these nuclear reactions that can happen with different isotopes of an element. So on your periodic table will be doing different types of the caves with different types of isotopes. So don't worry if your atomic mass on your periodic table doesn't match my atomic mass. That's because I'm dealing with a certain isotope of the element. Remember, isotopes have the same atomic number, so that the same element, but they have different number of neutrons, so we'll have different atomic masses. So here, polonium 2 10 means the atomic masses to 10. If you look on your periodic table, Polin IAM has an atomic number. Number of protons off 84. Now we're gonna undergo Alfa Decay. Alfa Decay means we're gonna spit out or emit a NALC a particle. You can represent it like this, or like this here, I'll just choose to show it as helium. So we're gonna emit for over two helium now, nuclear reactions air different from regular reactions. But there are some similarities. Just like you have to have a regular chemical reaction balanced. You have to have a nuclear reaction also balanced. So here are total atomic mass is to 10. Here we have already an atomic mass of four. So we need to create an element that when I added to the four, gives me back this mass of to 10. So the new element has to be 206 because 206 plus four gives me to 10. Also, your atomic numbers need to match on both sides. This atomic numbers, too. We need it to add up to 84. So we'd say that the new element would have toe have 82 because 82 plus two gives me 84. And what element would that be? Well, that would be led. So what we say here is that we'd say the alpha decay off. Puligny, Um 2. 10 creates a brand new element. Lead 206 Okay, the helium or the alpha particle is just something that we admit. That's just waste the new. The new element that we're concerned with is the lead 82 06 So this represents an Alfa decay, and it's a simple is that Make sure that your atomic masses add up on both sides. Make sure your atomic numbers add up on both sides.
Alpha Decay Concept 2
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Now, if we want to talk a little bit more about this alpha particle, we're gonna say in terms of size of radioactive particles were gonna say that the alpha particle is the largest, so it's bigger than your beta particle is bigger than your gamma particle, So your Alfa particle is the largest of them. Now it is the most damaging toe biological cells because it has the highest ionizing power. Which means that somehow if you got it into your body that it would just shred your insights, it would irradiate all of your biological cells in your body. Ah, person who is exposed to an alpha particle internally has very low chance of survival. The good thing is, because it has the highest ionizing power, and because it's so large, it's extremely difficult for to penetrate us, penetrate our skins and get into ourselves. So we're gonna say that has the lowest penetrating power we're gonna say that are close. Even the air around us provides protection against alpha particles getting into our bodies. Now, how could you get an Alfa particle inside of you? Maybe you work in a nuclear facility where you have contaminated water or contaminated food or there was some chemical leak and it got exposed in our environment in some way, and then you ingested it. But it's extremely hard for things like this to occur, so Alfa particles are extremely damaging to our insides. But the good thing is they're extremely hard to get into our bodies.
The alpha particle is one of the largest radioactive particles with the highest ionizing power, but lowest penetrating power.
Alpha Decay Example 1
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Now here we have to write the balanced nuclear equations for each other following Alfa emissions. So for Alfie mission again, that's the same thing as a decay. That means that the alpha particle will be a product. So here we have Curium 2 48. Remember these numbers here are atomic masses. You have to actually look on your periodic table to find out the atomic number of curium and bismuth. So cure him on our periodic table is 96. We know that we're going to basically emit an Alfa particle, so it's gonna have to be a product again. We have four already, so we have to make sure that the new element next to it adds up to 2. 48 on the other side. So it's gonna be 2 44 plus plus. Forgive me to 48 and down here, this house to be 94. And what does that give me that gives me P U plutonium and then bismuth 207 That's the atomic mass. The weight on the bottom would be 83. So we have B I, we admit a helium or alfa particle. So we have four here but we need to 07 So we had two or three over 81 and that gives me t all. It's that simple. Now, if they were to ask an Alfa Absorption or Alfa Capture and that means that these alfa particles wouldn't be would not be any more products. They'd be reacting. So, for example, you have 40/20 which is calcium, and then you do Alfa capture, so I'd be on the same side. And then all you have to do is just add these numbers up so it would be 40 plus four is 44 over 22 to give you a new element. So you just look on your periodic table and see what element has an atomic number of 22 that would represent an Alfa capture.