Class is structured so every class you fill out notes in your lecture book, so make sure you have your book on the first day. Lots of assumed knowledge so make sure you catch up on old chem concepts from HS, probably just by watching youtube videos. Can get away with using notes from the lectures to study for midterms, I had the class online and midterms were all MC. Midterms and final were very fair. Harmen is a great prof, he sometimes glances over things without explaining them in depth but if asked he will go over the concepts again in depth. He does teach very fast so you need to make sure you do not miss class. I also found he will say a lot of useful information that he doesn't write down, so taking extra notes in the margins helps.

Keep up with the weekly structure and you should be fine.