Chemistry Grade 11: Kinetic-Molecular Model of Liquids & Solids

Kinetic-Molecular Model of Liquids and Solids

• Intermolecular attractions exist between molecules, involving opposite charges.
• Intramolecular attractions occur within molecules, involving Covalent/Ionic bonding between elements.

Polar Covalent Forces

• Unequal sharing of electrons leads to polar covalent forces.
• Hydrogen bonds involve positive hydrogen attraction to negative oxygen, nitrogen, etc. and are the strongest.
• Dipole-Dipole forces occur between two ends with opposite charges.
• Ion-dipole forces occur between a cation/anion and a dipole.

Nonpolar Covalent Forces

• London Dispersion forces arise from random motions, inducing a temporary dipole.
• Van Der Waals forces are weaker and involve both molecules being induced.

Properties of Liquids and Solids

• Liquids have strong intermolecular attractions, are more dense and less compressible.
• Solids have stronger intermolecular forces, are not very compressible, rigid, and compact.
• Gases are disordered, highly compressible, and lack a definite shape.

Surface Tension

• Factors affecting surface tension include:
  • Adhesive forces between different molecules.
  • Cohesive forces between the same molecules.
  • Temperature.

Kinetic Molecular Theory

• The model explains the behavior of matter, stating that:
  • Particles are constantly in motion, with kinetic energy directly proportional to temperature.
  • Space exists between particles.
  • Attractive forces occur between particles, called intermolecular forces.
  • Temperature changes affect the state of a substance.

Viscosity

• Viscosity is the quantity of fluid resistance to flow.
• Kinematic viscosity measures a fluid's internal resistance to flow under gravitational force.
• High viscosity indicates strong intermolecular forces (e.g., honey).
• Low viscosity indicates weaker intermolecular forces (e.g., water).

Capillarity

• Rise of a liquid in a small passage occurs due to adhesive forces.
• The narrower the tube, the higher the liquid will rise.

Structure and Properties of Water

• Water molecules have covalent bonding between hydrogen and oxygen atoms.
• Water molecules carry no net electric charge, with 8 electrons not distributed uniformly.
• Water exhibits surface tension, with droplets forming a rounded shape due to adhesive forces.

Vapor Pressure

• Vapor pressure is the thermodynamic pressure exerted by a gas/vapor.
• Equilibrium is reached when evaporation equals condensation in a closed system.
• Volatile substances have high vapor pressure at normal temperatures.

Properties of Solids

• Solids have various properties, including conductivity, malleability, density, bonding, and structure.
• Electrical and thermal conductivity can vary, with some materials being insulators.

Boiling Point

• Boiling point is the temperature at which vapor pressure equals the surrounding pressure.
• Factors affecting boiling point include:
  • Higher altitude, resulting in lower pressure.
  • Higher temperature, resulting in higher pressure.

Molar Heat of Vaporization

• Energy is needed to convert liquid to gas.
• Vaporization (not liquid or gas) involves energy staying the same, with only temperature changing.

Melting Point

• Solid's melting point depends on the strength of interactions between its components.
• Various substances have different melting points, such as mercury (-38°C), tungsten (3433°C), and sodium chloride (801°C).

Solubility

• Solubility is the ability of a solid to dissolve in a particular solvent.
• Factors affecting solubility include:
  • Nature of the solute ("likes dissolve likes").
  • Temperature, with solubility directly proportional to absolute temperature.
  • Pressure, having a minimal effect on solubility.

Density

• Density is the amount of mass per unit volume.
• Crystalline solids exhibit anisotropy, with properties varying depending on direction.
• Amorphous solids lack a repeating lattice pattern and are also called pseudo solids.

Phase Changes

• Phase changes occur when the state of matter changes.
• Phase diagram illustrates the relationship between physical state, temperature, and pressure of a substance.
• Phase field, phase boundary, triple point, and critical point are all concepts related to phase changes.

Solutions

• Solutions are homogeneous mixtures of two or more substances with uniformly distributed compositions.
• Solute is the dissolved substance, and solvent is the dissolving medium.
• Concentration is the relative amount of solute and solvent.

Types of Solutions

• Dilute solution has a low concentration of solute.
• Saturated solution has the maximum amount of solute dissolved in a given amount of solvent.
• Supersaturated solution has more solute dissolved than the maximum amount.
• Hypotonic, isotonic, and hypertonic solutions vary in concentration relative to the cell.