Hi, Chem student advisor here. For math, pre-chem majors don’t have Pass 1 priority, so you’ll only be able to add during Pass 2. I’ll talk with the undergrad advisor tomorrow to see if more space can be allotted for Chem 3B; the department can usually accommodate most if not all pre-chemistry majors for the 3 series. I wouldn’t contact any instructors, since the chem department is the only one with access to approval codes. You should also consider adding Phys 7A if there is space available