kciray

I'd like to find some base course about general chemistry. At first I've seen some lectures in Khan academy, but I think they're very low quality and short. Where can I find hi-quality online lectures? I'd like one standard course, long (1-2 term) and detailed. What do you think about MIT courses?

Why mass number denominates "A" and atomic number - "Z" ? I couldn't find it anywhere. Maybe "A" derivated from some Latin word starts which "A"?