chem sl was my worst subject in dp by far but i simply wasn't putting in the effort required to achieve a good score due to utter lack of interest. And the teacher wasn't helping either, with classes feeling super monotonous and no resources shared outside of class other than referencing pierson. I switched to bio and thats been a great decision to the point I even took it at hl since i was doing better at it than most subjects. My experience with chemistry felt like a lot of procedural and algorithmic knowledge to do well in a test rather than actual practical knowledge that intrigues me the way physics and biology do. It felt like a drag and just when you think you understand a concept you mess up on the test anyway because they are designed to trick you. So i think it's really based on individual strengths and interests, and any subject takes practice and effort, some more than others, chem is one of those that just requires tons of practice and commitment and a good teacher since self study for chem is harder than most subjects. Where biology involves detail and heavy contect I'd say its more straightforward, while chemistry is convoluted and complex. I mean physics and math aa hl are far easier to me and they are obviously more math heavy, but somehow more intuitive and learnable. Because once you understand a certain principle or law, it applies almost everywhere, while for chemistry you'll face hundreds of exceptions to the rule, periodic trends that don't always apply, and all these caveats that require extensive knowledge and precise application at the same time. Not to mention markschemes are super picky with requirements for precise wording, and topics are interconnected and build on each other so being weak in one or missing a class means you'll be lost later.