 OK, so this is the last one of these problems we'll do. So which one of these has the stronger ionic bond? Hopefully already you've figured it out that it would be this one. Why is that? Because we've got a 2 plus here and a 2 minus. And here we've got just a plus and a 2 minus. So in fact, there's just like that. But anyways, so when we're talking about size and charge relative to strength of ionic bond, we have to recall that both play a part. And in this case, we find that the overall charge here is more than there. So the charge difference of the minus 2 to plus 1 sets you, again, somewhere in this range, OK? So in case we were comparing this, I believe this one to this one, and this time we're actually comparing this one to this one. So this would be where calcium sulfide is, and this is where potassium sulfide is. So we were to ask you which one has the stronger ionic bond. It would be calcium sulfide. And if you look at the melting points of these two compounds, this one is 8.43 Celsius. So again, this is a nice qualitative way of deciding which one has the stronger ionic bond.