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- Solids have fixed particles with strong forces, making them rigid and hard to compress.
- Solids have a definite shape and volume.
- Particles in solids vibrate about their mean position.
- Intermolecular forces in solids are strong, holding particles in fixed positions.
- Solids have a high density due to close packing of particles.
- Solids diffuse very slowly due to restricted particle movement.
- Solids expand little when heated.
- Solids melt at a specific temperature, turning into liquid.
- Some solids sublime, changing directly from solid to vapor.
- Crystalline solids have a definite geometrical shape and sharp melting points.
- Amorphous solids lack a regular arrangement of particles and have no sharp melting point.
- Crystal lattice is a 3D structural arrangement of particles in a crystalline solid.
- Unit cell is the smallest repeating pattern of a crystal lattice.
- NaCl has a face-centered cubic (FCC) structure with a 1:1 ratio of Na⁺ and Cl⁻ ions.
- Lattice energy is the energy released when an ionic solid forms from gaseous ions.
- Lattice energy decreases with increasing ion size and increases with higher ionic charge.
- Ionic solids are hard, brittle, and have high melting points.
- Ionic solids conduct electricity in molten/aqueous state.
- Covalent solids (diamond, graphite) have strong covalent bonds and high melting points.
- Covalent solids are generally poor conductors.
- Metallic solids have a “sea” of delocalized electrons, making them malleable and ductile.
- Metallic solids are good conductors of heat and electricity.
- Molecular solids have weak intermolecular forces and low melting points.
- Molecular solids are poor conductors.
- Crystal symmetry is determined by plane, axis, and center of symmetry.
- Crystalline solids exhibit anisotropy, with physical properties varying with direction.
- Isomorphism occurs when different solids have the same crystalline structure.
- Polymorphism is when a compound exists in multiple crystal structures.
- Allotropy is when an element exists in different crystal structures (e.g., diamond and graphite).
- Transition temperature is the point where two allotropes coexist.
- Ionic solids’ shape is influenced by ionic association and radius ratio.
- Graphite is a layered structure with weak van der Waals forces.
- Diamond is the hardest substance with a tetrahedral structure.
- Lattice energy values predict solubility and stability of ionic compounds.
- Ionic compounds with smaller lattice energy and greater hydration energy are more soluble in water.
- Born-Haber cycle calculates lattice energy indirectly.