How do glasses differ from crystalline solids in atomic arrangement?

The primary distinction between crystalline solids and glasses (a type of amorphous solid) lies in the presence or absence of long-range order.

• Crystalline Solids: These materials exhibit both short-range and long-range order. Their atomic positions follow a regular, repeating pattern known as translational periodicity, meaning the arrangement of atoms is predictable throughout the entire structure.12
• Glasses: These solids possess short-range order but lack long-range order. While atoms in a glass are not randomly distributed—they maintain specific chemical bond lengths and local neighbor arrangements similar to their crystalline counterparts—the overall structure lacks a repeating, periodic pattern at greater distances.12

Because of this lack of periodicity, glasses are often formed by the rapid cooling of a melt, which prevents the atoms from organizing into a stable crystalline lattice before their mobility is lost at the glass transition temperature. While the term "amorphous" literally means "without form," it is technically a misnomer, as glasses maintain well-defined local atomic structures dictated by chemical bonding.2