Final answer:
Malleability and ductility are distinct yet often correlated properties of metals due to metallic bonds. Malleability refers to the ability to be deformed into thin sheets, while ductility refers to the ability to be stretched into wires. Metals like lead can be malleable but not ductile due to differences in their crystal structure and other factors.
Step-by-step explanation:
The question asks about the difference between malleability and ductility, two mechanical properties of metals that are often associated with metallic bonds. It is indeed true that these properties typically arise from the ability of metal atoms to slide past each other without losing their cohesion, a feature enabled by metallic bonding. Malleability refers to a material's ability to deform under compressive stress, which means a malleable material can be hammered or rolled into thin sheets. On the other hand, ductility is a measure of a material's ability to stretch into a wire under tensile stress.
While these properties are connected and often co-occur in metals, they are not always present to the same degree. For example, lead is known to be malleable because its crystal structure allows it to be deformed into sheets without breaking. However, lead is not considered to be ductile; it lacks the ability to sustain tensile stress to be drawn into thin wires. This discrepancy can be attributed to variations in crystalline structure, impurities, grain size, and the presence of alloying elements, all of which affect a metal's mechanical properties.
Another important point is that while many metals are both malleable and ductile, this is not a rule. Each metal has its unique combination of mechanical properties, which depend on its atomic structure and the strength of its metallic bonds. For example, some metals might have defects or atomic arrangements that allow for easy compression but not extension.