Intermolecular Forces

• This force...

  • Attractive force between molecules.
  • Are the force of attraction between neighboring molecules.
  • Forces of attraction are caused by the formation of bonds between atoms.
  • Responsible for keeping matter in solid or liquid phase.

  Weaker attraction?

  Intermolecular Forces
• This force...

  • Force which keeps molecule together, i.e, bonds
  • Force which keeps molecule together in hands
  • Stronger than intermolecular forces
  • Bond formed within the atom.

  Intramolecular Forces
• This type of intermolecular force is the weakest type of intermolecular force.

  London Dispersion
• What is the other term for London Dispersion forces?

  Van Der Waals Forces
• In London Dispersion Forces, When 2 non-polar molecules approach each other, an instantaneous dipole moment forms.
• This type of intermolecular force exist between polar molecules. One end of a dipole attracts the oppositely charged end of the other dipole.


  Dipole-Dipole
• The higher the dipole moment, the stronger the intermolecular forces for substance to boil, and the higher the boiling point.
• This type of intermolecular force acts between an ion (either positive or negative) and a polar molecule.

  Ion-Dipole Forces
• Dispersion forces increase with increasing molecular mass and decrease with increasing distances between the molecules.
• This type of intermolecular force is a special type and very strong type of dipole-dipole force that exists between a Hydrogen atom bound to a small and highly electronegative non-metal atom.

  Hydrogen Bonding
• Hydrogen bonds occur in polar molecules containing H and any of highly electronegative elements, in particular Nitrogen (N), Fluorine (F), and Oxygen (O).
• This is the force of attraction between atoms or molecules.

  Dispersion Forces
• In Dispersion Forces:

  • Boiling point increases as dispersion forces increases.
• In Dispersion Forces:

  • As molar mass increase dispersion forces increase
• In Dispersion Forces:

  • Molar mass increase boiling point will also increase
• This refers to the force that causes the molecules on the surface of a liquid to be pushed together and contract.

  Surface Tension
• Surface tension explains why a drop of liquid is spherical in shape.
• The strength of surface tension depends on the intermolecular force of attraction (IMFA).
• The stronger the intermolecular force of attraction (IMFA), the greater the surface tension.
• Increase in temperature decrease surface tension as temperature breaks the force of attraction.
• Water has a high surface tension because of its high ability to form H-bond.
• This is the resistance (friction between molecules) of the fluids to flow.

  Viscosity
• In Viscosity:

  • A substance that flows readily has low viscosity like water.
• In Viscosity:

  • If the IMFA is strong, the liquid will have high viscosity because it will have a high resistance against flowing.
• In Viscosity:

  • The higher the temperature, the lower the liquid’s viscosity (as temperature breaks the bonding or increase kinetic energy)
• In Viscosity:

  • Maple syrup is more viscous than water because it has more H-bond that causes stronger IMFA.
• This is the force of evaporating molecules.

  Vapor Pressure
• This is defined as the temperature when the vapor pressure (760 Torr) of the liquid is equal to the atmospheric pressure (1 atm).

  Boiling Point
• This is the amount of heat needed to vaporize a given amount of substance at its boiling point.

  Heat of Vaporization
• The stronger the IMFA, the higher the heat of vaporization because higher energy is needed to convert them into the gaseous state.
• This is a change of state from liquid to gas.

  Vaporization
• This is a transformation of matter from one state to another that involves the absorption and evolution of heat.

  Phase Changes
• This involves sharing electrons between atoms.

  Covalent Bonding
• Name the 2 Types of Covalent Bond.

  Polar Covalent Bond

  Nonpolar Covalent Bond
• This covalent bond...

  • Unequal sharing of electrons between atoms.
  • One atom has greater attraction for shared pair

  Polar Covalent Bond
• This covalent bond...

  • Equal Sharing of electrons between two atoms.
  • Both atoms have same electrons for shared pair.

  Nonpolar Covalent Bond
• This is the power of an atom in a molecule to attract electron itself. This measures the ability of an atom to attract electrons from another atom.

  Electronegativity
• Identify the bond type based on electronegativity difference: 0 - 0.4.

  Nonpolar Covalent
• Identify the bond type based on electronegativity difference: >0.5 - 1.7.

  Polar Covalent
• Identify the bond type based on electronegativity difference: >1.8 or greater.

  Ionic