Transcription
In this video, we're going to go over uh radioactive decay, which is part of nuclear chemistry. So let's go over the different particles that you need to know. And let's start with the alpha particle. The alpha particle has a mass of four and a charge of two. The alpha particle is basically, it's the same or equivalent to the nucleus of a helium atom. So it can be written this way as well. That's an alpha particle.
The next one that you need to be familiar with is the beta particle, which can be written like this. It has a a mass of zero and a charge of negative 1. The beta particle is essentially the same as an electron.
Next in line, we have the positron particle, which is the anti-particle of an electron. So it has the beta symbol, but instead of having a negative charge, it has a plus one charge. So that's the positron. And then after that, you have the proton, which is much more massive than an electron. The proton has a mass of one and a charge of one. And then you have the neutron. The neutron is neutral. It has a mass of one, but a charge of zero. And then finally, the gamma particle. The gamma particle is basically a high energy photon. It has the gamma symbol, but it has a mass of zero and a charge is zero. So those are some particles and their symbols that you need to know.
So let's go over some examples. Let's say if we have nitrogen 13, and let's say it produces a beta particle, which can also be represented as the beta symbol, or you can put e for an electron. So that's the beta particle. What's the missing element now? The masses and the charges must be the same on both sides. So 0 + 13 is equal to 13. So the missing mass has to be 13. Now, what about the charge? -1 + what number is 7? -1 + 8 is 7. So the missing number is eight. To find a missing element, go to the periodic table and look for the element that has an atomic number of eight. So this is oxygen. So here, what we have is oxygen 13. So that's how you can find the missing element. So this is called beta decay. The reason why it's called beta decay or beta production is because this reaction is producing electrons, it's producing beta particles.
Now let's go back to uh this reaction. We need to understand understand the effect of beta decay. So notice that beta decay did not change the mass of the new element. The mass stayed the same. So any during beta decay, the mass will be constant. However, the atomic number changes. The atomic number increased from seven to 8. So beta decay causes the atomic number to go up. And the atomic number is basically uh the number of protons. So the number of protons went up. Nitrogen has seven protons, but oxygen has eight. But what about the number of neutrons? The number of neutrons is the difference between the mass number and the atomic number. So nitrogen has six neutrons, and oxygen has five. So the number of neutrons went down. So let's understand what happened. We lost a neutron, we gained a proton, and nitrogen also lost an electron. So basically, a neutron in nitrogen was converted into a proton and electron. That's basically what happened. A neutron in the nitrogen nucleus was converted to a proton. The proton stayed in a nucleus, but the electron left. And so that's why we could see we have a decrease in a neutron number, an increase in a proton number, and electron it escaped from the atom or from the nucleus of the atom.
The next kind of reaction that we're going to talk about is positron production. So we're going to produce a positron in this reaction. So if we're producing it, it's going to be on the right side. So this time, it's going to be 0 positive 1. And let's use the beta symbol. Now, what's the missing element? Now the mass is going to be the same, it's going to be 13. But now the atomic number is going to be 7 minus 1, which is six. So what's the missing element here? What element has an atomic number of six? This is no other than carbon. So what is the effect of positron production? So this time, the atomic number went down. It decreased from 7 to six. So whenever the atomic number goes down, we said the number of protons decreases. But what happened to the neutron number? Well, 13 - 7 is 6. So nitrogen had six six neutrons. 13 - 6 is 7. So now it has seven neutrons. So the neutron number went up. So basically, a proton was converted into a neutron and a positron. So let's rewrite it a different way. So here's the proton with a mass of one and a charge of one. It was converted into a neutron, which had a mass of one and a charge of zero, and it was converted also into a positron, which has a mass of zero and a charge of one. So a positron is just an anti-particle of the electron. You can see how it's balanced. 1 + 0 is 1, and 0 + 1 is 1. So that's what happened uh during positron production. A proton was converted into a neutron and a positron.
By the way, what happens when a positron meets with an electron? When these two get together, they cancel out and they form a gamma particle. So as you can see, 1 + 1 um is zero. So they basically annihilate each other, emitting gamma radiation.
The next type of decay we're going to talk about is electron capture. So what exactly is an electron capture? Well, sometimes the nucleus of an atom can capture one of its uh inner core electrons. And so let's see what happens. Let's say if we have a arsenic 73. Arsenic has an atomic number of 33. And if the nucleus captures an electron, the electron has to be on the left side. So what element will be produced? 73 + 0, well, that's going to stay 73. 33 + 1 is 32. So arsenic is going to change into germanium if the nucleus of the arsenic atom captures an inner core electron. So let's see what happens within a nucleus. So the atomic number went down. It went from 33 to 32. So we lost a proton. The proton number went down. Now the number of neutrons is the mass number minus the atomic number. So 73 - 33, arsenic has 40 neutrons. And 73 - 32, germanium has 41 neutrons. So we gained a neutron by acquiring an electron. So let's see what happened here. So in a nucleus, a proton, which has a mass of one and a charge of one, combined with an electron to create a neutron. 1 + 0 is 1, and 1 + 1 is 0. So that's what happens during electron capture. The proton and the electron, they come together, they form a neutron, and the element changes. The atomic number decreases by one.
And now the last thing we're going to talk about is alpha particle production. So let's say if we have element P, which has an atomic number of 84. And since we're producing alpha particles, we need to put it on the right side. So what's the missing element? So 210 - 4 is uh 206. And 84 - 2 is 82. So the element with the atomic number of 82, that is PB, that's lead. And so this is alpha particle production. And basically, you just got to make sure the reaction is balanced. As long as the masses and the atomic numbers, or the charges, are the same on both sides of the equation, then you're good. That's it. So that's just an intro into nuclear chemistry and different types of uh radioactive decay. So that is it for this video. Thanks for watching and have a great day.