CHEM2

• When energy is added, particles move faster. When energy is taken away, particles move slower
• Intermolecular Forces vs Intramolecular Forces

  • INTRAMOLECULAR FORCES: Ionic, Covalent, Metallic
  • INTERMOLECULAR FORCES: Ion-Dipole, Dipole-Dipole, Dipole-Induced-Dipole, H-bonding, Dispersion (London)
• Dipole-Dipole forces


  Attraction between two polar molecules, electrostatic attraction between ends in dipole-dipole forces
• 1. Bonding


  Attractive forces between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule, hydrogen needs to be attached to a highly electronegative atom like oxygen, fluoride, or nitrogen
• Viscosity

  Resistance of liquid to flow, depends on the strength of intermolecular forces where stronger forces mean higher viscosity, decreases with an increase in temperature
• Properties Of Liquids And Intermolecular Forces

  1. Surface Tension

  2. Viscosity

  3. Capillary Action

  4. Vapor Pressure

  5. Boiling Point
• Adhesive Forces


  Forces of attraction between a liquid and another substance
• Types of attraction in molecules

  • Intermolecular bonds
  • Intermolecular forces
• Matter is anything that has mass and takes up space
• Dipole-Induced-Dipole forces

  Between polar and non-polar substances, can occur when one molecule with a permanent dipole repels another molecule's electron, inducing a dipole moment in that molecule
• Ion-Dipole forces


  Strongest of the weak forces, ions attract polar molecules, important role in dissolving ions in water, enough of these can break crystal lattice
• Dispersion or Van Der Waals forces

  Weakest intermolecular force, occurs in all types of molecules, sum of attractive or repulsive forces between molecules, named after Johannes Diderik van Der Waals
• Capillary Action

  Occurs when water goes up a narrow tube against the forces of gravity, how plants and trees transport water from roots to leaves where photosynthesis occurs
• Surface Tension

  Measure of inward forces that must be overcome to expand the surface area of a liquid
• Vapor Pressure

  When liquid is placed in a closed container, the molecules that escape or evaporate from the liquid into gas phase will cause pressure on the container
• Transport of water from roots to leaves where photosynthesis occurs

  Capillary Action
• Electronegativity


  Ability of an atom to attract electrons towards itself in a chemical bond. It plays a major role in chemical bonding
• Cohesive Forces


  Forces that hold liquid together. Attraction to same molecules. Example: Water to Water
• Molar Heat of Vaporization


  Defined as the energy that must be absorbed in order to convert a liquid to gas at its boiling point
• Melting or Freezing Points

  The temperature at which the liquid and solid states of a substance co-exist is called the melting point. The melting point of ice and the freezing point of water are the same temperature. Melting point is when solid changes to liquid, and freezing point is when liquid changes to solid
• Non-Polar vs Polar


  • Nonpolar: Covalent bonds where two atoms share a pair of electrons. Polar: Covalent bonding where a pair of electrons is unequally shared between two atoms
• Structure and Properties of Water
• Sublimation

  Process of passing directly from solid to gas phase without passing through the liquid state. Example: Moth Balls, Dry Ice
• Properties of Solids

  • Melting or Freezing Points
  • Sublimation
• Capillary Action


  Drawing of a liquid inside a small-bore tube when adhesive forces exceed cohesive forces
• Boiling Point

  Defined as the temperature at which the vapor pressure of liquid is equal to the atmospheric pressure. Water has a boiling point of 100C, meaning at 100C, water changes from liquid to gas
• Dynamic Equilibrium

  The rate at which ice is melting is equal to the rate at which the liquid is freezing. Melting and freezing points depend on the forces of attraction between particles
• Electronegativity Value Difference and Interpretation

  • Greater than 1.8: Ionic, Polar
  • 0.5 to 1.8: Covalent, Polar
  • Less than 0.5: Covalent, Non-Polar
• Adhesive Forces

  Forces of attraction between a liquid and another surface. Attraction to something different. Example: Water to Glass
• Heat of Fusion is the amount of heat required to melt one gram of a solid at its melting point at constant temperature
• How to Determine if a Compound is Covalent or Ionic

  Calculate the difference in electronegativity of the atoms involved by subtracting the larger value from the smaller one
• Sublimation

  • Moth Balls
  • Dry Ice
• Chemical Formula

  1 molecule of water is made up of 2 hydrogen atoms bonded with 1 oxygen atom
• Types Of Geometric Forms Of Crystalline Solids

  • Cubic
  • Hexagonal
  • Monoclinic
  • Orthorhombic
  • Rhombohedral
  • Tetragonal
  • Triclinic
• Heat of Fusion


  The amount of heat required to melt one gram of a solid at its melting point at constant temperature
• Activity

  1. Surface Tension

  2. Viscosity

  3. Capillary Action

  4. Vapor Pressure

  5. Boiling Point
• Types Of Solids


  • Summary of Types of Solids
• When a solid changes directly to a gas

  Sublimation
• Water is referred to as the universal solvent
• Structure And Properties Of Water

  • Water is the most common and most abundant chemical compound on the earth
  • Water covers approx. 75% of the earth’s surface and is necessary for all living organisms
  • Pure water at room temperature is a colorless, tasteless liquid
  • Water has the highest specific heat of liquids and solids except NH3
  • Water has the highest heat of fusion of all molecular substances
  • Water has the highest surface tension of all molecular solids
  • Water has the highest thermal conductivity of all molecular liquids