biochem and chem are completely different. simple question to solve that problem might be something along these lines
what's more interesting to you, functional groups and the way they interact, or DNA?
I chose functional groups and I'm quite glad of it. A chem major will lead you to synthesis and how to build big molecules (insanely cool imho), whereas biochem will lead you towards big molecules and how they interact.
What seems more interesting? And yeah, if you can handle physics (I can't) then that seems like an excellent choice.