Final answer:
The term 'malleable' is used to describe a substance that can be hammered or rolled into thin sheets. This physical property is typical of metals due to the nature of metallic bonding, which allows ion layers to slide past each other without breaking.
Step-by-step explanation:
The adjective that describes the physical property of a substance that can be hammered into thin sheets or films is malleable. Malleability is a characteristic of materials, usually metals, that allows them to be deformed under compressive stress; this is often characterized by the material's ability to form a thin sheet when hammered or rolled. Examples of malleable materials include gold, silver, and aluminum, which can be rolled into thin sheets or beaten into complex shapes without breaking. Metallic solids display a high level of malleability due to the nature of metallic bonding, where s valence electrons are shared among a lattice of positive ions, allowing the layers of atoms to slide over each other without fracturing the solid. The presence of free-flowing electrons between the stationary cations in a metal allows it to maintain cohesion under stress, which contributes to its malleability and ductility, another property that denotes a material's ability to be drawn into wires.