Which statement describes the difference between crystalline and amorphous solids?

Which statement describes the difference between crystalline and amorphous solids?

• A. Crystalline solids have a sharp melting point; amorphous solids soften over a range.
• B. Amorphous solids have a sharp melting point; crystalline solids soften.
• C. Both have sharp melting points.
• D. Amorphous solids never melt.

Answer: (A)

The main idea here is how a solid’s internal structure affects how it melts. Crystalline solids have a highly ordered, repeating arrangement of particles, while amorphous solids lack long-range order. Because crystals have a uniform lattice, when they reach their melting temperature the entire structure tends to break apart at roughly the same energy, giving a definite, sharp melting point. Amorphous solids don’t have that uniform lattice, so different regions soften or rearrange at different temperatures. As you heat an amorphous solid, it gradually becomes softer and more fluid over a range of temperatures rather than melting at a single point. That’s why the statement describing crystalline solids as having a sharp melting point and amorphous solids as softening over a range best captures the difference. For context, ice melts at a specific temperature, while glass softens over a temperature span rather than at one precise temperature.

The main idea here is how a solid’s internal structure affects how it melts. Crystalline solids have a highly ordered, repeating arrangement of particles, while amorphous solids lack long-range order. Because crystals have a uniform lattice, when they reach their melting temperature the entire structure tends to break apart at roughly the same energy, giving a definite, sharp melting point. Amorphous solids don’t have that uniform lattice, so different regions soften or rearrange at different temperatures. As you heat an amorphous solid, it gradually becomes softer and more fluid over a range of temperatures rather than melting at a single point. That’s why the statement describing crystalline solids as having a sharp melting point and amorphous solids as softening over a range best captures the difference. For context, ice melts at a specific temperature, while glass softens over a temperature span rather than at one precise temperature.