all right, so we've discussed isotopes being elements that have the same number of protons but different number of neutrons. The way we represent these isotopes is through what we call isotope notation. Now this is just the representation for an isotope, and it includes its atomic number, which, remember, is Z. It's mass number, which is a and now it's elements Symbol X. Remember, our periodic table of the elements has the display of all the elements that we know off with their elemental symbols. For example, carbon is represented by the elements symbol seat in this example. Down below we have calcium, which is represented by C A. Typically, when we talk about isotope notation, we have our mass number presented here on top on the bottom. We typically have our atomic number Z on the bottom and then the symbol for the element here. So if we take a look at this question, it's telling us that we have calcium 43 it represents one of the isotopes for the calcium Adam. If the number 43 represents its mass number, determine the correct numbers for it's a subatomic particles. All right, so we're gonna say calcium 43 again, I say. Within the example, Question 43 represents its mass number, which is this number right here. Here. It's mass numbers 43 Its atomic number is 20. And the elements symbolist see a representing calcium. All right, remember that the atomic number Z is equal to the number of protons here. The atomic number is 20. So that means we have 20 protons. So that means our answer at this point can either be a or D. So be in Sierra next. Let's determine the number off neutrons because that's the next subatomic particle that shown we're going to say here that remember, up above we said the number of neutrons equals your mass number, which is a minus your atomic number, which is Z. So if we look at this isotopic symbol for calcium, we see that the mass number is minus Okay, 20. So that's gonna give us 23 neutrons. So we have 23 neutrons. A says we have 43 neutrons. We know that cannot be the answer. So it looks like D is the correct choice, not let's talk about the number of electrons. How do we determine the number of electrons? Well, they say the word Adam within the question. Remember, we're talking about the word, Adam. We're dealing with the neutral element for neutral element. The number of electrons equals the number of protons. So since my number of protons is 20 my number of electrons also must be 20. So the answer here would be D Now, remember, with Adams, we're dealing with neutral elements. Number of protons and electrons are equal. If they had said the word ion, then with the word ion, that would mean that the number of electrons and protons would be different. We haven't quite gotten there, but just remember that we're eventually gonna get to a point where the number of electrons and protons will not be the same. In those cases, we will no longer have a neutral element. It will have a charge. Okay, but for this example, because we're dealing with Adam, let's just focus on the fact that we have the same number of protons and electrons