Solid
Definition and meaning of Solid in chemistry.
Solid is a state of matter with a fixed shape and volume, in which particles (atoms, ions, or molecules) are tightly packed and held in place by strong interparticle forces or bonds, ionic, covalent, metallic, or intermolecular, depending on the substance. Solids are largely incompressible and maintain their form unless broken, melted, or otherwise altered.
In more detail
In a solid, atoms, ions, or molecules vibrate about fixed positions within a crystalline lattice or amorphous structure, rather than moving freely. Crystalline solids typically have a sharp, definite melting point at which thermal energy overcomes the interparticle forces or bonds holding the structure together, allowing the solid to transition into a liquid. Amorphous solids, by contrast, lack a sharp melting point and instead soften gradually over a range of temperatures at the glass transition. Solids can be either crystalline (with ordered atomic arrangement, like table salt) or amorphous (with disordered arrangement, like glass). The strength and type of interparticle forces or bonds determine properties such as hardness, melting point, and electrical conductivity.
Key facts
| State of Matter | One of three main states (solid, liquid, gas) |
|---|---|
| Particle Motion | Vibrations in fixed positions only |
| Structure Types | Crystalline (ordered) or amorphous (disordered) |
| Field | Physical Chemistry |
Sodium chloride (table salt, NaCl) is a crystalline ionic solid at room temperature with a cubic crystal structure. It melts at 801 degrees Celsius and is incompressible under normal pressure.
Frequently asked questions
What is the difference between crystalline and amorphous solids?
Crystalline solids have atoms arranged in a repeating ordered pattern, giving them a definite melting point and geometric crystal shape. Amorphous solids lack long-range order, with particles randomly arranged, giving them no distinct melting point and no characteristic shape (like glass).
How do solids change state?
Solids melt into liquids when heated above their melting point, or sublime directly into gas under certain conditions (like dry ice subliming to CO2 gas). They reform through freezing or deposition.