California needs good high school chemistry teachers. First, you need a B.S. in a scientific discipline and must have Gen Chem I/II, O-Chem I/II. This is the minimum. Then you must acquire a Master's degree in education, i.e. complete a certified credentialing program.
If you want to be a stellar chemistry teacher, you're much better off with a B.S in chemistry as the minimum requirement. In terms of competitiveness, it's nowhere near as competitive compared to becoming a history teacher.
If you're really good at what you do, and if you're willing to teach in Los Angeles, then you may be eligible for a paid credentialing program. It's important you understand what teaching in LA means, especially East LA.