But is it the right thing that should be surprisingly difficult in chemistry class? I mean, we learned to disregard the nature of ions floating in the solution, as long as those ions can or cannot bind to each other. Great! You can probably explain things about sets, intersections, etc., to people who are used to such operations, but how is it chemistry? How does it control our anticipations about compounds (beyond a restricted range of interactions)? Analytical chem is not taught in high school (wasn't in ours, anyway).