A matter can exist in four states- solid, liquid, gaseous, and plasma. The main characteristic that differentiates the solid from the other states of matter is its rigidity or hardness. The liquids and gases are not hard in nature and can flow; therefore, they possess fluidity.
Solids have a definite mass, shape, and volume. Liquids have a definite volume but no actual form, and it takes the shape of the container it occupies. Gases have no actual shape and no definite volume.
Solids being hard in nature, they cannot be compressed or pressed into smaller shapes; they are incompressible. They can only be cut into smaller shapes.
The constituent particles that form the solid structure do not move from their place and occupy fixed positions. The strong intermolecular forces hold the molecules in place. The distance between these particles, the intermolecular distance, is minimal.
Although the molecules inside the solid occupy fixed positions, they are not stationary but show vibrational motion. The particles vibrate about their mean position like the pendulum’s constant side-to-side motion. However, this energy in solids is less and can be increased externally using heat energy. The increase in temperature can increase vibrations, eventually weakening the attractive intramolecular forces. The particles will become free to go into the liquid and the gaseous state. Therefore, low thermal and vibrational energy preserves the solid-state.
The characteristic five properties of the solid-state can be summarized as follows:
The strong intermolecular forces hold the constituent particles (atoms, ions, or molecules) in fixed positions. The intermolecular distance between the particles is less, and they have low vibrational and thermal energy. Therefore, solids are rigid, incompressible, and have a definite shape, mass, and volume.
All these features are responsible for a substance to exist as a solid.