Do you mean CHEM5? New spec?
If so, definitely nothing synoptic from Unit 4 can be in Unit 5 (since schools can do those two papers in either order), and I suggest you look at the only REAL paper for that unit, the January 2010 one. The synoptic content on that was small and was mostly basic Unit 1 and 2 knowledge you should know anyway (shapes of molecules, oxidation states, periodicity of Na to S).