GEN CHEM

• Phase


  - A homogeneous part of a system in interacting with other parts of the system but

  separated from these other parts by well-defined boundaries.
• Intermolecular forces


  - are attractive forces between molecules. These attractive forces are generally much weaker than bonding

  forces.
• The different types of intermolecular forces are the following:

  1. Dispersion forces

  2. Dipole-dipole forces

  3. Ion-Dipole Forces

  4. Hydrogen bond
• 1. Dispersion forces


  - also called as London dispersion forces, when temporary dipole

  moment is induced in ordinarily nonpolar molecule, dispersion forces result.

  Dispersion forces may be the weakest of intermolecular forces that can exist between

  two molecules, but the larger the atoms present, the stronger are the dispersion forces.
• ion-induced dipole

  interaction.


  The attractive interaction between a polar molecule and the induced dipole is called
• Diffuse cloud


  - is an electron cloud that is spread over an appreciable volume, so that the electrons are not held tightly by the nucleus.
• 
  

  Dipole-dipole forces


  are attractive forces between polar molecules (molecules that

  possess dipole moments). In polar molecules, the electrons are unequally distributed due

  to the difference of the electronegativities of the atoms. The partial positive side of one

  molecule is attracted to the partial negative side of another molecule.
• Dipole-dipole


  forces are stronger than the dispersion forces because polar molecules have a

  permanent unequal spread of electrons.
• 3. Ion-Dipole Forces


  attract an ion (either a cation or an anion) and a polar molecule to each

  other. These types of forces can also be explained by Coulomb's law. The

  charge and size of the ion, the magnitude of the dipole moment and size of the molecule

  greatly influence the strength of this interaction.
• 
  

  Hydrogen bond .


  is a generally strong force of attraction. It is a special type of dipole-dipole

  interaction between the hydrogen atom in a polar bond, such as N‒H, O‒H, or F‒H, and

  an electronegative O, N, or F atom. Hydrogen bonds between water molecules are

  particularly strong. The interaction is written as:

  A ‒ H ••• B or A ‒ H ••• A
• Intramolecular forces


  - hold atoms together in a molecule.
• the kinetic molecular theory


  The experimental findings about the behavior of gases can be explained with a simple

  theoretical model known as

  
  

  This theory is based on the

  following assumptions:

  1. All matter is made of tiny particles.

  2. These particles are in constant motion.

  3. The speed of particles is proportional to temperature. Increased temperature

  means greater speed.

  4. Solids, liquids, and gases differ in distances between particles, in the freedom of

  motion of particles, and in the extent to which the particles interact
• Fluid


  - A liquid or gas; a substance that flows.
• Surface tension


  - It is the elastic force in the surface of a liquid. It is the amount of energy required to increase or stretch the surface of a liquid by a unit area.
• Capillary action


  - It is the tendency of a liquid to rise in narrow tubes or to be drawn into small openings.
• Viscosity


  - A measure of a fluid's resistance to flow.
• Vapor


  - A gaseous substance that exists naturally as a solid or liquid at normal temperature.
• Vaporization


  - The change of phase from liquid to gas/vapor.
• Vapor pressure of a liquid


  - The pressure exerted by the vapor above the surface of the liquid in a closed container. It is the equilibrium pressure of a vapor above its liquid.
• Boiling point


  - The temperature at which liquid boils.
• Molar heat of vaporization (ΔHvap)


  - The amount of energy (usually in kilojoules) required to vaporize 1 mole of a liquid at a specific temperature.
• 1. Surface Tension


  - Molecules within a liquid are pulled in all directions by intermolecular forces. There is no tendency for them to be pulled in any one way.
• Surface tension


  is a measure of the elastic force on a liquid's surface. It is the amount of energy needed by a unit area to stretch or increase the surface of a fluid (for example, by 1 cm2).
• Capillary action is brought on by two types of forces:

  cohesion and adhesion
• Cohesion


  is the intermolecular attraction between similar molecules (water molecules, in this

  case).
• Adhesion


  is an attraction between unlike molecules, such as those in water and in

  the sides of a glass tube.
• 
  

  Viscosity


  is a measure of the resistance of a fluid to flow. The greater the , the more the liquid flows steadily.
• 3. Vapor Pressure


  By evaporation, molecules may escape from the surface of a liquid into the gas phase. The pressure of the vapor reaches a constant value after a short period, which we call
• dynamic equilibrium


  The situation in which two opposing processes occur at equal rates simultaneously is

  called
• The vapor pressure of a liquid


  is the pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium.
• 4. Boiling Point


  is the temperature at which its vapor pressure, acting on the liquid surface, equals the external pressure.
• 5. Molar Heat of Vaporization


  A measure of the strength of intermolecular forces in a liquid is the molar heat of vaporization (ΔHvap), defined as the energy (usually in kilojoules) required to vaporize 1 mole of a liquid.