CO1

• Solid


  molecules that are held together rigidly in position

  molecules that do not freely move

  less empty space than in liquids; incompressible
• Liquid


  difficult to compress than gases

  denser under normal conditions

  molecules that are held together by more than one type of attractive forces
• Gas


  molecules separated by large distances

  huge empty spaces between molecules; readily compressed

  lack strong forces between molecules
• Matter is made up of atoms and molecules that are always moving
• Any form or type of matter hold kinetic energy and move around in random directions
• High temperatures → high energy

  Low temperatures → less energy
• The more kinetic energy, the faster the movement.
• In solids, particles hardly move and hold a regular pattern because the kinetic energy is low, and they are tightly packed
• In liquids, the particles have a higher kinetic energy than those in solids and hence, they are free to move.
• In gases, particles have the highest kinetic energy because they are dispersed and move around freely.
• Intermolecular Force


  attractive forces between molecules
• Intramolecular Force


  attractive forces that hold atoms together in molecule
• Intermolecular forces are much weaker than intramolecular forces
• Types of Intermolecular Force

  Ion-Ion Force (Strongest)

  Ion-Dipole Force

  Hydrogen Bonding

  Dipole-Dipole Interaction

  Dispersion Forces (weakest)
• Ions


  charged atoms or molecule
• Dipole


  a molecule that has both positive and negative regions that are separated with each other
• Electronegativity


  the ability of an atom to attract shared electrons

  how much electrons wants to be near an element
• Polar


  that possess dipole moments, which arise from differences in electronegativities

  molecule has one slightly positive end and end slightly negative end

  central atom with lone pair

  terminal atoms are not symmetrically arranged
• Non Polar


  Compounds having the same atom / monoatomic molecules.

  Central atoms without lone pairs

  All of the terminal atoms (or groups) are symmetrically arranged

  Organic compound
• Ion-ion Force


  attractive force between positive and negative ions

  also known as ionic bonds

  strongest force in all intermolecular force
• Cation


  ion that loses the electron becomes a positively charged ion
• Anion


  gains electrons becomes negatively charged ion
• Ion-dipole Force


  forces that attract an ion (either a cation or anion) and a polar molecule to each other
• Strength of Ion-dipole Force

  charge and size of the ion

  magnitude of the dipole moment

  size of the molecule
• Hydrogen Bonding


  Special type of dipole-dipole interaction between the hydrogen atom in a polar bond and an electronegative (O, N, F)

  Average strength of a hydrogen bond is quite large for a dipole-dipole interaction(up to 40 kJ/mol)

  Hydrogen bonds have a powerful effect on the structures and properties of many compounds
• Dipole-dipole interaction


  Attractive forces between polar molecules (between oppositely charged ends of polar molecules)

  Molecules have dipole moments

  The larger the dipole moment (larger difference in electronegativity), the larger is the dipole-dipole force.
• Dispersion Force


  Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules due to the proximity of an ion or polar molecule

  Present in all molecules (Polar, Non-polar, Ionic)

  Monoatomic substances and non-polar molecules

  Dispersion forces usually increase with molar mass
• Intermolecular forces influence three properties

  Rate of Evaporation

  Boiling Point

  Solubility
• Rate of Evaporation


  Evaporation requires the input of energy, specifically the enthalpy of vaporization

  The value for the enthalpy of vaporization has a positive sign → evaporation is an endothermic process.

  The enthalpy change for the condensation process → has a negative value

  The greater the forces of attraction between molecules in a liquid, the greater the energy that must be supplied to separate them
• Boiling Point


  As the temperature of a substance is raised, its molecules gain kinetic energy

  When the boiling point is reached, the molecules have sufficient kinetic energy to escape the forces of attraction of their neighbors

  Stronger Intermolecular force = High Boiling Point
• Solubility


  Like dissolves like

  Polar Solute and Polar Solvent

  Non-polar Solute and Non-polar Solvent
• Properties of Liquid

  Surface Tension

  Capillary Action

  Viscosity

  Vapor Pressure

  Boiling Point

  Relative Humidity
• Surface Tension


  Amount of energy required to stretch or increase the surface of a liquid by a unit area

  Liquids with strong intermolecular forces have high surface tension
• Capillary Action


  Tendency of a liquid to rise in narrow tubes or be drawn into small openings such as those between grains of a rock

  Happens when a liquid flows through a material because of the attraction between the molecules of the liquid and the material (solid)
• Cohesive Force


  intermolecular forces between the molecules of liquid
• Adhesive Force


  interaction between the liquid and solid surface
• Concave Meniscus


  Adhesion
• Convex Meniscus


  Cohesive
• Viscosity


  A measure of a fluid’s resistance to flow

  Strong intermolecular force, high viscosity

  High temperature, more kinetic energy results to high viscosity

  Large molecules have difficulty in moving
• Three Factors that Determine Viscosity

  Strength of Intermolecular Force

  Shape of the Molecule

  Temperature