Properties of Solids
Section 1: General Properties of Solids
- Solids have a fixed shape and a definite volume due to strong intermolecular forces that keep the particles closely packed together.
- The particles in a solid are located at fixed positions and can only vibrate about their mean positions.
- Solids are incompressible as there is very little space between particles.
- Solids have high density because particles are closely packed.
Section 2: Crystalline and Amorphous Solids
- Solids can be either crystalline or amorphous based on the arrangement of their constituent particles.
- Crystalline solids have particles arranged in an orderly, repeating pattern extending in all three spatial dimensions. Examples include metals and diamond.
- Amorphous solids, like glass and plastics, do not have a regular arrangement of particles.
Section 3: Types of Crystalline Solids
- Crystalline solids can be further subdivided into: ionic, metallic, covalent, and molecular solids.
- Ionic solids are composed of positive and negative ions and are held together by ionic bonds.
- Metallic solids consist of metal cations surrounded by a sea of delocalised electrons.
- Covalent solids or network solids have atoms held together by network of covalent bonds. Diamond and quartz are examples.
- Molecular solids are comprised of molecules held together by intermolecular forces like dispersion forces, dipole-dipole forces, and hydrogen bonds.
Section 4: Properties Based on Types of Solids
- Ionic solids are hard, brittle, have high melting points and conduct electricity when molten or in solution due to the mobility of ions.
- Metallic solids are shiny, malleable, ductile, have variable hardness and melting points, and are good conductors of heat and electricity.
- Covalent solids are very hard, have very high melting points and do not conduct electricity.
- Molecular solids have low melting points and do not conduct electricity as they do not have free electrons or ions.