Teach the alternative to chemical periodicity.
Chemical Periodicity: 112 elements and counting, and they keep rearranging the periodic table! Where will it stop?
Intelligent Chemistry:
4 elements: Earth, Air, Fire, and Water. Hasn't changed in millenia. If it was good enough for the ancient Greeks, it's good enough to be taught in science class.
You have exactly the right idea.
See http://www.re-discovery.org/ for an amusing description of what you posted.