What characteristic defines a solid compared to other states of matter?

A solid is defined by having both a definite shape and volume. This means that the particles in a solid are closely packed together in a fixed arrangement, which gives the solid its rigidity. Unlike liquids and gases, solids do not conform to the shape of their container; instead, they maintain their own shape regardless of the external environment. This characteristic is a direct result of strong intermolecular forces that keep the particles in fixed positions.

In contrast, liquids have a definite volume but no definite shape, allowing them to take the shape of their container, and gases have neither a definite shape nor a definite volume, expanding to fill any available space. The ability to flow is also a property of liquids and gases, but not solids, which further emphasizes the distinction between these states of matter. Understanding these characteristics is crucial for identifying and classifying different materials in chemistry.