STRUCTURAL FEATURES OF SOLID

• Solids


  • Definite shape and volume
  • Noncompressible due to lack of spaces between particles
• Diamond is known as the hardest natural substance to exist in the world
• Not all solids are like diamonds. Some are soft and can be easily manipulated, while others are brittle and strong resistance to shape
• Kinetic Molecular Theory of Solids


  A simple microscopic model that explains the three different phases (solid, liquid, and gas) of matter and how they can change from one phase to another
• All matter is composed of particles that have a certain amount of energy to make them move at different speeds depending on temperature
• Temperature


  Average kinetic energy of particles in a system
• Particles in a solid state

  • Held together by strong covalent or ionic bonding
  • Noncompressible due to lack of spaces between them
  • Definite shape and volume
• Crystalline solids


  Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern, held together by uniform, strong intermolecular forces
• Crystalline solids


  • Quartz
  • Sodium chloride
• Unit cell


  The small repeating pattern in crystalline solids, made up of unique arrangement of atoms, representing the structure of the solid
• Amorphous solids


  Solids that lack the order found in crystalline solids, with structures at the atomic level similar to the structures of liquids
• Amorphous solids


  • Obsidian (volcanic glass)
  • Rubber
• Crystalline solids consist of particles in an organized form, while the particles of amorphous solids are not formed in an orderly manner
• Melting point


  The temperature at which a solid loses its definite shape and is converted to a liquid
• Freezing point


  The temperature at which a liquid changes to a solid
• At the melting/freezing point, solid and liquid forms of a substance are in equilibrium with each other
• Crystalline solids have a precise melting point, while amorphous solids melt over a wide range of temperature
• A stronger interaction has a higher melting point
• Melting points


  • Cristobalite melts at 1713 oC
  • Soda-lime glass can melt between 550 OC and 1450 oC
• Heat of fusion


  The quantity of heat necessary to melt a solid
• Solids with stronger intermolecular forces have higher values of heat of fusion
• Crystalline solids have a fixed and definite heat of fusion, while amorphous solids have no precise value
• Sublimation


  The process of direct passage from solid to vapor phase, bypassing the liquid state
• Deposition


  The reverse process of sublimation (vapor to solid phase)
• Enthalpy of sublimation


  The quantity of heat to convert solid to vapor
• Ice exhibits an appreciable sublimation pressure (4.58 mm Hg)
• Anisotropy


  The property of substances where the physical and mechanical properties vary with different orientation and molecular axes, exhibited by crystalline solids
• Isotropy


  The property of substances where the physical and mechanical properties are equal in all directions, exhibited by amorphous solids
• Malleability


  The ability of a solid to undergo compressive stress without breaking
• Ductility


  The ability of a solid to undergo tensile stress
• Most of the time, malleability and ductility properties coexist
• Gold is known to be the most malleable and ductile
• Electrical conductivity


  The measurement of the ability of atoms, molecules, or ions to transfer electrons from one to another
• Thermal conductivity


  The measurement of the ability of atoms, molecules, or ions to move and collide with its neighboring particles
• Solids with nondirectional bonds (metallic) have high malleability and ductility, and are good conductors, while solids with rigid bonds (ionic/covalent) are brittle and heat insulators
• Why is copper used to make electrical wires?

  Copper has high electrical conductivity due to its metallic bonds
• Classify the following as crystalline or amorphous solids

  • Precise heat of fusion - Crystalline
  • Wide range of melting temperature - Amorphous
  • Cotton candy - Amorphous
  • Anisotropic - Crystalline
  • Dry ice - Crystalline
• Crystalline Solids

  • the orderly arrangement of atoms: highly regular shapes
  • examples: quartz and sodium chloride
• Amorphous Solids

  • from the Greek words for “without form”
  • lacks the order found in crystalline solids
  • structures at the atomic level similar to the structures of liquids
• Amorphous Solids

  • atoms, ions, or molecules have little freedom to move unlike in liquids
  • do not have well-defined shapes of a crystal
  • examples: obsidian (volcanic glass) and rubber