 Let's do the electron configuration for strontium, so I know some of you looked up there I know, but it's all right. So strontium is SR. Okay, so look for it on the periodic table So it's 38, right? So you're looking for 38 electrons, so let's Write the electron configuration. Okay, so how do we do it? We look at the periodic table. Let's write it together What is it? 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, so that's where it gets weird, right? So 3d10, 4p6, 5s2, 5s2. Okay, that makes sense, right? So you can also, if you were like, okay, I don't know, count these up, right? And then you can figure out, it didn't tell you what is this atom, right? You can count them up and figure out what atom it is. Let's do the condensed electron configuration. Condensed abbreviated noble gas electron configuration, you'll hear all of those terms. They're interchangeable. Okay, so how do we do the noble gas configuration of any element? Noble gas and then add the what? The valence electrons. Yeah, the remainder electrons are called the valence, okay? So what's the noble gas before strontium? Crypton, so valence electrons. So all these are the inner electrons, right? And tell where? That, right? So those are all the inner electrons and these ones here are the valence. Okay, so let's predict the ion that strontium was made. SR2 plus, right? Why would you think that? Because you've got two valence electrons here. Okay, so again, this is a common ion. So let's draw the condensed electron configuration for the common ion of strontium. What would it be? Now let's draw what's called the orbital diagram for the valence electrons of strontium. Okay, so the orbital diagram, you write, so for the valence, of course, we've got crypton before that, so all this is the valence. So we've got, if we look up where strontium is, it's the 5s, 4d, 5p. Okay, 4d. So that's the valence shell, right? Okay, but strontium doesn't fill all that up, right? So strontium only has the two electrons. So they're just going to go into the 5s. So one, and why don't they go up here? Because that's higher in energy. Bunking with the guy next door. Okay, so remember, so plus and minus. So that's the electron partial orbital diagram for the valence electrons.