 Okay, so again, this is just like the last problem except this is an anion instead of a cation. Okay? So for the following symbol, we'll get the atomic number, et cetera, et cetera. So first, we have phosphorus. So with no the atomic number, we just look at the periodic table, you'll always have one. Right? We look up there, it says it's 15. Right? That's the atomic number of phosphorus. Okay? The mass number is given to us here is 32. Okay? The number of protons equals the atomic number. Okay? So the number of protons is going to be 15. The number of neutrons is the mass number minus the number of protons. Okay? So that's going to be, in this case, 17. The number of electrons. So now we've got to look at this particular symbol and it's got a charge associated with it. Okay? With that charge, since it's a 3 minus, we know that 3 electrons have been added to the neutral atom. Okay? So the neutral atom should have the same number of protons as electrons. So if that's the case, the neutral atom has 15 electrons. We add 3 to that. Right? We're going to get 18 electrons. Okay? Now we look at the number of valence electrons. Well in this case, phosphorus is here. Right? Normally it has 1, 2, 3, 4, 5 valence electrons, but we've done a lot to it. Added 3 more. Right? So we go 1, 2, 3. So now it has the argon configuration or 8 valence electrons. Okay? We've got 8 valence electrons there. Okay? And then to determine how many inner electrons you have, you don't count the valence shell, but you count everything else. Right? So you're going to take the number of electrons, subtract the number of electrons from the valence shell, and you get the number of inner electrons. Okay? Does that make sense?