Write balanced nuclear equations for the following processes. (b) Electron capture of 138Sm

Video transcript

Welcome back everyone. In this example, we need to give the balanced nuclear equation when isotope selenium 72 decays by electron capture. So given from the prompt, we have our isotope selenium 72. Recall that on our period table selenium corresponds to the atomic number being 34 and it's undergoing an electron capture. So this we recall is a beta particle where we have a mass number of negative one, sorry, a atomic number of negative one and a mass number of zero. So what we need to do is figure out the product that is produced from this electron capture where we have this unknown chemical symbol Z representing our atomic number which we need to solve for and a representing our mass number which we need to solve for. So we're going to have to set up two expressions to sulfur A and Z we're figuring out Z is ultimately going to tell us our identity of our unknown element product here. So beginning with our solution for finding a, we'll use the color red for our atomic mass number. We plug in our notes. So on our reactant side, we have a mass number of 72 for selenium added to our mass number. For our electron beta particle being zero. We set this equal to our product side where we have our unknown mass number. A. And solving for a, we would have that A is equal to 72 moving on to the solution for our atomic number. Z we'll use the color purple for that. We'll say that Z our atomic number plugging in our nos is going to be equal to our known atomic number of selenium being 34 added to our atomic number for the electron beta particle being negative one set equal to our unknown atomic number. And this means that our value for our atomic number is going to equal 33. When we find atomic number 33 on the periodic table, we would see that this corresponds to the atom asinine A S meaning that we have the symbol for our bound nuclear equation where we have selenium 72 undergoing an electron capture. So reacting with an electron here producing our product symbol where we have asinine corresponding to atomic number 33 and the mass number being 72. And so this entire equation here is going to be our balanced nuclear equation. As our final answer when selenium 72 decays by electron capture, I hope everything I reviewed was clear. If you have any questions, please leave them down below. And I will see everyone in the next practice video