Weiss is super self-absorbed. He spends most of the class bragging about himself and his famous friends. He also likes to give snippets of advice that he thinks are super helpful but are usually just self-aggrandizing anecdotes that don't have practical applications to students' lives. It's not hard to do well in this class, but it is hard to sit through listening to him at lectures.

Paul is definitely a GREAT professor for Chem 20BH!
First of all, I believe all of you who are viewing this page must have noticed the difference between Paul's rating for Chem 20B and Chem 20BH. This arises from the different nature of these two: If you just want to learn some chemistry and pass 20B(H) as easily as possible, stay away from Paul's class; if you want to really learn SCIENCE, including chemistry and involving all aspects of science (research skills, analytic skills, etc.), you can hardly find a better professor than Paul.
Second, I acknowledge that the workload is heavy, but it is well manageable. In the quarter I took this Paul's class (winter quarter of my first year ---- as most of you who will take this course will most probably take at this time of the year), I took 5 courses including 2 maths and a cluster and I survived. Other comments have talked about what to expect, and they are all precise. However, if you are very academic, you will definitely handle all this.
Last but not least, Paul is pretty chill. Just think about how many 60-year-old professor would like their students to call them by their first name instead of Prof. X or Dr. X. His class is extremely interesting, where Paul would occasionally tell jokes and personal experience. And again, if you are a very science guy and want to get into a lab, Paul is extremely helpful. He knows who to turn to regarding every aspect of chemistry or materials science if he can't answer himself.
The only minor problem with this course is that the exams are very comprehensive. As other comments have said, many of the materials are complementary, which results in a heavy workload. It will be great if you command them all, but since most of us can't, you should be wise at telling the most important points from others (as I did). Other than that, Paul's course is very amazing.

MK. This is gonna be a long one.

This class is kinda wild and I'm still not sure if I should've taken it. I feel like it should probably be an 8 unit class or called Chem 20BHW or something because I literally wrote more in this class than in any other humanities class that I've taken here so far.

There are tons of pros of taking this class. First and foremost, if you want to get into a lab and are not really sure how- Paul will get you into one probably guaranteed. When you're sending out inquiries you can cc him and he'll vouch for your ability which can help. However, it's not completely necessary since I didn't cc him and still got into one of my top choice labs, so I'm kinda wondering if the rest of the class was worth it. Again though, if you're worried about it he will definitely help you be more knowledgeable about the research all the faculty does and will help you narrow down, so it's worth it in that regard.

You learn a lot but it's more intuition and scientific methods rather than actual chemistry as I studied very little and relied heavily on my AP Chem knowledge to do well in the class. The tests weren't too bad and are actually not too big of a part of the grade. When I looked up his syllabus I thought this would be great as I choke pretty frequently on tests and am really good at doing psets etc., but legit be warned. If you're taking a large amount of units like I did + lab this class will actually drown you.

Let's start with the cons. The thing I probably detested the most about this class is that the homework (book problems) had very little to do with the course overall. You did them after reading the chapter and probably never saw them again. There were so many small things and complicated problems that I had to churn out but then never saw discussed in the class or test so it kind of encouraged not actually learning those skills. Aside from the book problems, every 1.5 weeks you'll have a "literature assignment" that requires you to read a paper and then summarize it. This takes SO long. Please do not underestimate trying to basically read a foreign language for your first assignments bc it's so hard. Legit try to find shorter articles and it will help you even if it's less interesting. This will however definitely help you start reading papers which is a necessary skill but it takes a huge amount of time. This reading papers slowly builds into your poster project and paper which requires even more papers to be read and takes one of your saturdays later in the quarter to go and present in front of your peers. I pulled multiple all-nighters for this as I also had other classes that I had to be focusing on which really sucked. It was a delightful experience overall but so much work. Finally, the pacing is awful because after this poster presentation which had a homework assignment literally due a few days after as well as a midterm. That was quite fun and I bombed the second one but still ended up getting an A. I think you prob shouldn't worry about your grade as much as your health in this class :(

Overall, just know when he says it's 3x the work it really is. You'll learn a lot about chemistry but not with too much of a focus on 20B material and rather it's real-world applications. Stay safe :)

TLDR: The class is a ton of work, but if you're planning on a career or major in science, it's completely worth it. You'll learn general chemistry principles like in 20B, albeit with a bit deeper understanding, and parallel to that you'll become literate at reading current scientific research. Also, if you want to do research as an undergrad, Paul is your guy and WILL hook you up with a position.

Compared to Chem 20B, this class is about 3-4 times as much work. In addition to the weekly homework assignment (problems from the textbook), Paul assigns weekly "creative problems," where we create and solve problems related to the current course material, and we have 5-6 literature assignments, which have us write reports on research articles published within the past year. In addition to a final exam you'll be assigned a lengthy final project, where you detail some current research area with a 5-10 page paper, presentation, and poster. And lastly, Paul assigns an "auxiliary assignment" each quarter, which are about the same amount of work as a syllabus assignment (but you can do multiple for extra credit). Sometimes it could be pretty nauseating doing the sheer amount of work that is assigned, but it is possible to do it if you don't procrastinate.

The class teaches the general chemistry principles that 20B does. Stuff like molecular bonding, electrochemistry, nuclear chemistry etc. But Paul puts special emphasis on adding in research-oriented content in his lectures. By that I mean he often teaches you about the experimental setups necessary to discover all the principles we learn about. This includes all the different types of mass spectrometry available, the different types of ways to "fingerprint" an atom/molecule, and flow cytometry. He cares that you learn more about the guiding principles and how to derive specific points of knowledge rather than memorize them (Like being able to tell him how to find an atomic radius rather than memorizing it for a couple atoms).

One con of the class is just how much background knowledge Paul assumes everyone has. Sure there's the tryhards who did research in high school, but fo someone coming out of AP Chem or Chem20A/AH, the first couple weeks it is VERY tough to follow along with Paul as he dives into anecdotes about his colleagues' research.

All in all, the class is extremely daunting if you don't have a very solid foundation in chemistry or don't plan on majoring in biology/biochem. However, it is definitely possible to adjust to Paul's pacing, and after a week or two you'll get a much better grasp at what the hell he's talking about. By the end (with enough effort), you can consider yourself relatively scientifically literate. If that's a goal of yours, this class is definitely worth the time, but I would recommend making sure all your other classes are easy.

This professor is absolutely fantastic. He is very invested in his students and we as a class were all on a first name basis. I absolutely recommend this class if you are also interested in entering a lab! He will help you out A LOT!! 100kJ/mol = 1 eV !! He teaches a lot of intuition and thinking in the class as well! The TA, Kris Barr was also fantastic as well :)

Prof. Weiss meets every standard for a good professor, except that his lack of organization and dabbling into sophisticated and irrelevant subjects most of the class did not understand made his class a pain in the butt for any non-bio/chem majors.

Don't make the same mistake I did. Take that other professor.

Professor Weiss cares more about student mastery of the material than any other professor I've had. Would definitely recommend to anyone who wants to truly master this courses's curriculum as well as material that was removed from the course.

Professor Weiss has entirely changed 20B from the normal syllabus of the class, he assigns homework and reading from the textbook but after the first month I completely stopped doing the reading because it has NOTHING to do with what you will talk about in lecture or what you will be tested over. His teaching and testing style are the weirdest and worst I have ever encountered, you can definitely tell that he is a researcher and not a professor (he doesn't let you forget it either because he brings up all his published papers and awards and friends who are nobel laureates every five seconds). He's a nice guy, but definitely not used to teaching this large of a class at this level and it shows, I don't think he prepared me very well for 30A and I did not enjoy his class, if you can take someone else, I would highly recommend doing so.

This class was supposed to be titled "Chemical Energetics and Change"
But what actually taught by Weiss were:
x-ray photoemission spectroscopy, x-ray diffraction crystallography, flow cytometry, fluorescent in-situ hybridization, silicone polymers, biopolymers, direct and indirect-band gap semiconductors, semimetals, semi-insulating semiconductors, and so on.

And yes, as you expected, these topics are designed not just for fun - they DiD appear on the exams, which were purely conceptual (no calculators were allowed, by the way, because there were NO questions involving any quantitative calculations). While the topics that were supposed to be in the syllabus - entropy, enthalpy calculations, acid-bases, kinetics, etc. were barely covered during lectures, which appeared to as highly incoherent, disorganized and strangely paced ("flow of consciousness" should be a better term) as a typical episode from Rick and Morty - that is, you never know what's coming up next.

I would recommend Weiss to all kids who are chemo-nerds/maniacs and enjoy bragging hours after hours about nanotechnology. However, if you intend to take chem20B to gain some true, fundamental and organized knowledge of chemistry, Weiss would never be your first choice.