Final answer:
The shear strength of a metal is influenced by its atomic arrangement, bonding, and the mobility of free electrons which allow metals to deform under stress without breaking.
Step-by-step explanation:
At the atomic level, the shear strength of a metal is generally determined by the arrangement and bonding of atoms in its crystal lattice, and the presence of free-flowing electrons. Atoms in a metal are packed closely together in a repeating pattern. When shear stress is applied, the ability of free electrons to move around the stationary metal cations allows the crystal structure to deform without breaking, similar to ball bearings coated with oil sliding past one another. This attribute of metals contributes to their malleability and ductility, which means they can be hammered into shapes, rolled into thin sheets, or drawn into thin wires without fracturing. Additionally, conductivity and malleability depend on how easily electrons can be removed, and thus, metallic character increases down a group in the periodic table.
Another aspect is that the specifics of the spatial arrangement of atoms in the unit cells of metals impact their various properties, including shear strength. Different metals have different crystal geometries, which partially determine their unique mechanical properties. Fundamentally, shear strength is related to atomic-scale interactions, the metallic bond strength, and the crystal structure of the metal.