This class is basically high school AP Chemistry with very few new things thrown in. The only part of this class that sucked was the homework. It doesn't seem like much on paper, but the textbook problems are pretty convoluted. The exams were fairly simple and in almost no way related to the homework, so feel free to Chegg the homework or something to get full points on that. The exams were graded pretty harshly due to their simplicity, so be wary of that. Just study with people who've had good experiences with AP Chem, and you should be fine.

Professor Weiss is a textbook narcissist. He cares more about himself than the class or the lectures. He his honestly overqualified to be teaching lower division chemistry. For a majority of the class, he proceeds to tell us stories about his personal life or from his research projects. On top of this, he assigns a ton of homework every single day and it's due the next class. The TAs for this class were not helpful either. You had to study almost everything on your own. The biggest problem is that you never know where to study for the exams from because the questions are not from his slides or the textbook or anything else. Would never recommend Weiss to anyone... just find a better alternative!

Professor Weiss was a fantastic teacher and just extremely interesting and kind in general. His office hours were always a blast and helped a lot.

Honestly, Weiss is a very enthusiastic person who genuinely enjoys going to lectures and even woke up at 4 in the morning one week to give skype lectures from abroad.

However, this class is really not the best place to learn anything that is in te course name "Chemical Energetics and Change". Towards the end of the first week, it was pretty apparent that the way that Weiss was teaching gas laws was overly simplified and not really helpful for students in doing the homework. In addition, he would occasionally interrupt the topic to start speaking about the various kinds of spectroscopies, which a lot of people found interesting, but it really took away from the time he could have spent teaching gas laws. Starting second week, I started going to Li's lectures because I felt that if I was going to learn anything this quarter about chemistry, it was not gonna be from this class.

I didn't know how bad the class was going to be though. Starting third week, we started thermochemistry while the homework followed the book and was on questions of phase equilibria. I think I gave up on trying to find what he talked about interesting when he went into semiconductors. It just was not what I felt that I wanted to or needed to learn from the course. When the unit got into thermodynamics, a lot of people were stuck on the harder problems because we had no idea whether to spend our time trying to keep up with what Weiss was teaching us, or to try to learn the concepts in the book to solve the homework problems.

Of course, the latter would have been very good for learning the topics we were supposed to in this course, but it probably would have killed my grade in this class. Even though the stuff we were supposed to be learning was gas laws and phase equilibria in the first 2 weeks, the first midterm (based on the first 2 weeks) largely tested the various types of spectroscopies. The second midterm, in turn largely tested electrochemistry and semiconductors while we were supposed to be learning thermodynamics. I don't think that the final had any material we were supposed to be learning in the course at all. The tests were all qualitative, usually involving very little math and mostly just describing how things work; really just regurgitating what he tells you.

The TA will probably be your lifeline in this course to doing homework and understanding either what the book tells you and what Weiss tells you. But that is also a lot of stuff to fit in 50 minutes so you should definitely go to office hours. Weiss's own office hours were actually pretty inconvenient for me and I didn't really like him anyways so I didn't go. But I heard that he doesn't really have anything that he could use to show students how to do problems; no whiteboard or chalkboard. So I guess the office hours are best for asking him questions on the lectures.

The class had 3 midterms, but everyone is allowed to drop one midterm. I really don't know how good that is if everyone gets curved at the end of the class though...

All in all, I really regret taking this professor, but I sat through Li's lectures and she completely skipped over acid-base equilibria. That is not to say that Weiss did it well, but rather that we understood that we had to self-teach ourselves it.

Professor Weiss is the smartest man I've ever met! He made this class very interesting and helpful for future purposes.
IMPORTANT NOTICE: This class is extremely challenging. If you do not have the time to fully invest daily hours of work for this class, do not take it. This class' workload is 3 times more than the regular Chem 20B class. There are creative problems to do each week, literature assignments, and also homework from the book. On top of that, there is a final project (poster + paper) that must be completed and is worth 15% of your grade. The only way to achieve your best is to try very hard on the homework (worth 30% of the grade), and to try and score above average on the tests.
Also, stay in contact with the TA's because at times their information is very confusing and the guidelines are difficult to understand. My experience with the TA's was rather disappointing because of their harsh grading and lack of communication, so please make sure that you precisely understand want they want. You can always ask Paul for help if you feel lost.

Warning: this class is A LOT of work. Weekly homework, literature assignments, and readings. Add that onto a final project, poster, and essay. Oh and midterms and finals, of course.
However, the class itself isn't that bad, and I don't regret taking it. Paul really does want all of his students to do well, and he'll help you get into a research group if you're set on one already. The TA's are also pretty cool, although their discussion worksheets do not help at all with the midterms and finals. If you enjoy learning chemistry for the sake of chemistry (like me), you'll like the class.
The bottom line is, if you're willing to put in the work and effort, you'll do fine in the class. It's whether or not you're willing to do all that work (as in, I took 4 classes that quarter and 20BH was half of my homework/studying time)

Weiss is definitely the best professor I've had at UCLA. Brilliant guy and very helpful. The only office hours I've ever attended were his and it was more for discussion and stories than help in the class. He is very well connected and willing to help you with anything inside or outside of his class. He hooks everyone up with lab positions and will talk to other professors about you to get you a position. I still see him around and say hello and talk a bit. What a guy.

Paul was a wonderful and approachable professor. The class itself was tedious (so much homework! There's weekly homework problems, a poster presentation and paper, creative questions, and literature assignments), but the exams were reasonable as long as you study. Much of the class (besides a few concepts) was a review of AP Chemistry, so the concepts weren't too difficult, but Paul definitely makes interesting test questions that requires you to apply these concepts to new scenarios.

Of course it's a lot of work, but it's satisfying work if you do it. Really great class for prospective any prospective chemistry-related majors. Weiss also cares a lot about your learning and is really nice guy. You won't regret doing this class.

Pretty shocked at how low his 20B reviews are. He's probably my favorite professor. Maybe if you're a tryhard, he's the kind of professor for you. He places a lot of emphasis on putting work into getting good grades - it's really hard not to do well if you try.