Which statement describes a solid with a sharp melting point?

Which statement describes a solid with a sharp melting point?

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

Answer: (A)

Melting point sharpness comes from how orderly the solid’s structure is. Crystalline solids have a regular, repeating arrangement of particles, so the bonds that hold the lattice together are uniform throughout. When temperature reaches a specific value, enough energy is available to overcome those bonds everywhere at once, and the solid changes to liquid at essentially one temperature. That creates a sharp melting point. Amorphous solids lack long-range order; their particles are arranged irregularly, and bonds break over a range of energies. As a result, they soften and flow gradually rather than melting abruptly at a single temperature. So crystalline solids show a sharp melting point, while amorphous solids melt over a range. For example, ice melts at a precise 0°C under standard pressure, whereas glass softens over a span of temperatures.

Melting point sharpness comes from how orderly the solid’s structure is. Crystalline solids have a regular, repeating arrangement of particles, so the bonds that hold the lattice together are uniform throughout. When temperature reaches a specific value, enough energy is available to overcome those bonds everywhere at once, and the solid changes to liquid at essentially one temperature. That creates a sharp melting point. Amorphous solids lack long-range order; their particles are arranged irregularly, and bonds break over a range of energies. As a result, they soften and flow gradually rather than melting abruptly at a single temperature. So crystalline solids show a sharp melting point, while amorphous solids melt over a range. For example, ice melts at a precise 0°C under standard pressure, whereas glass softens over a span of temperatures.