I don’t know… I hate to discourage you from trying it, but your old chemistry teacher, who knows more about your capabilities than I do, appears reluctant to encourage you, and your AP record isn’t all that great. If you take AP Chem, I’d make it the only AP, IB or honors class that you take that year. It is one of the most difficult - if not THE most difficult in some high schools - of all the AP classes.