Final answer:
Particles in solids vibrate about fixed positions due to strong intermolecular attractions, forming a structured pattern or a disordered configuration in crystalline and amorphous solids respectively, giving solids their definite shape and volume.
Step-by-step explanation:
At the most basic level, particles in a solid are positioned very closely to each other, typically in a structured, geometric array known as a crystal lattice, if the material is crystalline in nature. These particles are not stationary, but they are limited to vibrate about their fixed positions due to strong intermolecular attractions that hold them in a definite structure. This restricted motion is why a solid has a rigid shape and retains a defined volume. As temperature increases, these vibrations become more intense, which is indicative of increased thermal energy within the solid.
In comparison, amorphous solids, such as glass, lack such regular patterns. Their particles are still tightly packed but in a disordered, random configuration that results in varied properties, such as the ability to bend under stress without breaking, a characteristic not usually found in crystalline solids.
Solids can transition into other states of matter when supplied with enough energy, typically in the form of heat, to overcome the intermolecular forces. For example, when a solid reaches its melting point, its particles gain sufficient energy to move past one another, leading to the liquid state, which has a fixed volume but not a fixed shape.