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Ch.21 - Nuclear Chemistry

Chapter 21, Problem 15a

Decay of which nucleus will lead to the following products: (a) bismuth-211 by beta decay?

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Hello everyone in this video. We want to identify this unknown species right over here in the equation. So let's go and get started. So in a radioactive decay or emission reaction, the radioactive particles ejected from the nucleus and from the product. So whenever we have a beta decay or beta emission, this occurs when an unstable nucleus ejects a beta particle to go ahead and create a new element. What a beta particle is has no atomic mass and is represented by an electron. So you can either write it like so or like So same thing for right. And the left on the top, we're gonna go ahead and have this be the mass number. And on the bottom we'll have our atomic number. Alright, So an element can be represented as very similarly we have our X let's say. And then A. And Z. So this X. Is going to be our element symbol. Same thing on top of each is the mass number on the bottom will be our atomic number. Alright, so kind of filling that in for equation then. So we have our X A Z. Go and bring down to our 1 87. On top bottom is 76 0. S. Plus that electron. All right. So, we can see here that we have these products. So our mass number of activities is equal to the mass number of products are mass number of the unknown is equal to the mask Number of beta particle plus the mass number of W. So in words or numbers then we have the a equals to Which is the mass number of either the unknown directions equaling or adding to zero. So that just means that automatically. Let's see we have 1 87 plus zero. That's 1 87. Now for our Z. Value. So this is a. Then we'll have C. Next at the atomic number react is equal to the atomic number of products. The atomic number unknown is equal to the atomic number of beta particle plus atomic number of new elements. So our atomic number on noon is Z. That's equal to the atomic number of beta particle which is negative one. The atomic number of new elements is 76. So negative one plus 76 is 75. The atomic number now that we have soft for it. We can go ahead and look at the P. R. A. Table and we see that for 75 that's going to be this uranium elements which has the symbol of our eve. Let's go ahead and write out our balanced nuclear equation then. So we have this R. E. On top is 1 87. Bottom is 75. This goes ahead to have 1 76 0. S. Plus the electron. Alrighty. And this is going to be my final answer for this question. Thank you all so much for watching