I once passed a 3rd year thermodynamics course (physic) in a top University by attending at most 4 classes (1st day, mid-term, final and I don't remember if I showed up for any other day), actually I think I aced that course. Not exactly a chemistry class, but as any arrogant physics grads would tell you, physics > chemistry.
But anyway all class presentation/note should be available online, in either pdf or ppt format. Failing to do that is just laziness in the Professors' part. And remember to some people (like myself), going to class is just a waste of my time since it doesn't fit my learning style at all. (Non-linear, multi-reference learning style is how I learn, and google/internet is the best for that).
Then again, I suppose there are profs. out there who think testing students on gotchas that they only talk about in class is somehow beneficial to students. To that, I say I'm glad I'm done school! (at least for now)