Which characteristics best define crystalline solids?

Crystalline solids are defined by their ordered arrangement of particles. This structure means that the constituent particles—whether they are atoms, molecules, or ions—are arranged in a highly ordered and repeating pattern that extends in three dimensions. This regularity gives crystalline solids distinct geometric shapes and well-defined edges, as well as consistent physical properties, such as melting points, that are characteristic of the substance.

The ordered structure means that crystalline solids typically have a uniform composition throughout the material, which contributes to their physical stability and predictability in behavior. This contrasts with characteristics such as randomness in arrangement, non-uniform composition, and variability in properties with temperature, which are more representative of amorphous solids or other types of materials. Thus, the hallmark of crystalline solids is their orderly and repeating lattice structure, which is essential to many of their physical properties.