Information is all here:
http://sydney.edu.au/handbooks/scie..._of_study/table1_nanoscience_technology.shtml
Basically the nanoscience major requires an interdisciplinary study program from chemistry, physics and engineering (two or more out of the three). Senior year you have to take a minimum 4 out of these 6 subjects:
CHEM3112/3912
CHEM3116/3916
MECH3361
MECH3362
PHYS3039/3939
PHYS3099/3999
They all have their own prerequisites. If you wanted to do the chemistry or physics units, the minimum you would have to do would be the first year courses, and the compulsory second year ones (CHEM2401/2911/2915 and CHEM2402/2912/2916, and for Physics, PHYS2011/2911 and PHYS2012/2912). The engineering units would need just ENGG1802 first year, and AMME2301 and AMME2302 the next. The rest of your units are optional.
If you've combined it with engineering, depending on what senior units you intend to take, it's basically the same except the units for both degrees would be included in your program.