Final answer:
A copper block can be hammered into a sheet because it exhibits malleability and ductility, due to its metallic bonding with free-flowing electrons that allow atoms to slide over each other and maintain the metallic structure while being deformed.
Step-by-step explanation:
A block of copper can be hammered into a sheet because it is malleable and ductile. These properties are due to the unique arrangement of its metallic bonding, which involves a sea of free-flowing electrons around stationary cations. The flexibility in metallic bonds allows the atoms to slide past each other without breaking the metal structure.
Copper's conduction electrons are only loosely bound to the nucleus, making it easier for them to move throughout the material, allowing for excellent electrical conductivity. This characteristic is also what enables copper to be bent, hammered, and stretched without breaking.