I have a short assingment on the difference between the atomical makeups of aluminum foil and sandwich wrap and why is it that even though they are both physically real, one ( the foil) is not transparent, and the other (the wrap) is transparent. I need help on how I go about finding this out?

I think that it has something to do with the valence electrons and how they fit together on the last ring and how there is a difference in the gaps between the electrons which makes the wrap transparent, but that's just an borderline educated guesstimate.

While this won't help you answer the wider question (why are all opaque materials opaque), it might help you to answer this specific question.

What's special about the electronic configuration in aluminium? It's the same phenomenon that makes aluminium shiny and conductive. Any ideas?