Final answer:
Amorphous solids are isotropic, with uniform properties in all directions due to their lack of a regular internal structure, unlike anisotropic crystalline solids, which have directional properties.
Step-by-step explanation:
Amorphous solids are isotropic in nature, which means their properties are the same in all directions. Unlike crystalline solids, which have a regular and repeating three-dimensional structure, amorphous solids lack such an ordered internal structure. This is due to the random arrangement of particles within the solid, resulting in uniform properties throughout the material. For example, glass and plastics are types of amorphous solids and do not have a long-term repeating pattern like that of a crystal of sodium chloride (NaCl), which is a crystalline solid.
The properties of amorphous solids differ from those of crystalline solids since the latter are anisotropic, meaning their properties change depending on the direction in which they are measured. Amorphous solids do not have sharp melting points and do not exhibit regular planes of cleavage that are characteristic of crystalline solids. Substances that form amorphous solids typically include large molecules or a mixture of molecules with restricted movement, such as candle waxes composed of large hydrocarbon molecules.