In the solid state, particles are tightly packed together and have limited movement, typically only vibrating in place. This arrangement results in solids maintaining a fixed shape and volume. The strong forces between the particles—whether ionic, covalent, or metallic—keep the molecules or atoms in a rigid structure, which prevents them from flowing or spreading out. As a result, solids have a definite form and cannot be easily compressed. Common examples include ice, metal, and wood, which maintain their shape at a given temperature and pressure.
The characteristics of solids depend on the type of bonding between their particles. In crystalline solids, the particles are arranged in a highly ordered structure, forming regular patterns that extend in three dimensions. This structure gives crystalline solids specific geometric shapes, such as cubic or hexagonal forms. In contrast, amorphous solids, like glass or rubber, lack this regular arrangement, resulting in materials that can be more flexible and may not fracture as easily as crystalline solids. Despite these differences, all solids share the common property of having a fixed shape and volume due to the restricted movement of their particles.