Aluminum (Al) is widely used as a packaging material, especially in the form of foil, cans (for beverages and food), and as a layer in laminated packaging, due to its low cost, malleability, and excellent barrier properties against light, moisture, and oxygen. It also forms a protective oxide layer that prevents corrosion.

Cu (Copper): Copper is not typically used for food packaging due to its reactivity and potential to leach into food, which can be harmful.

Fe (Iron): Iron is the primary component of steel used in cans (often as tinplate or tin-free steel), but it is usually coated to prevent rust and interactions with food. Aluminum (Al) is more commonly and widely used for flexible packaging like foils and for many beverage cans without needing extensive internal coatings.

Na (Sodium): Sodium is a highly reactive alkali metal that reacts violently with water and is unsuitable and dangerous for use as a packaging material.