GenChem 2 Q3

• When solids or liquids are heated up, the kinetic energy of their particles increases causing them to move faster.
• As temperature and kinetic energy rises there comes a time that the movement of the particles overcome the forces of attraction between each particles and they change phase. Solids can melt or sublime and liquids can vaporize.
• The strength of interaction of these particles accounts for the physical properties or characteristics of solids and liquids.
• The kinetic molecular theory is a simple but very effective model that effectively explains ideal gas behavior.
• The kinetic molecular theory is based on the assumption that all states of matter have component molecules that possess kinetic energy.
• Assumptions of the KMT explain the shape and volume of matter in three states.
• Matter in the gas state does not have definite shape and volume. It can fill a container of any size and shape.
• Matter in the liquid state does not have definite shape but has definite volume. The shape is not definite because the molecules have enough energy to slide over one another and slip out of the ordered arrangement to conform to or follow the shape of their container.
• Matter in the solid state has definite shape and definite volume because of the very strong attractive forces between the component particles and their low kinetic energies.
• Intramolecular forces are the forces that hold atoms together within a molecule. Intermolecular forces are forces that exist between molecules.
• Intermolecular forces are attractive forces holding the particles of substances together. There are different kinds of intermolecular forces.
• Kinetic energy is the energy of particles in motion. It keeps the particles apart from each other. It counters the effect of intermolecular forces and it is proportional to the increase in temperature.
• Types of Intramolecular Forces:

  1. Ionic Bond
  2. Covalent Bond
  3. Metallic Bond
• Ionic Bonds

  This bond is formed by the complete transfer of valence electron between atoms.
• Ionic Bond

  It is a type of chemical bond that generates two oppositely charged ions.
• In Ionic Bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.
• Covalent Bond

  This bond is formed between atoms that have similar electronegatives—the affinity or desire for electrons. Because both atoms have similar affinity for electrons and neither has a tendency to donate them, they share electrons in order to achieve octet configuration and become more stable.
• Two types of Covalent Bonds:

  1. Polar Covalent Bond
  2. Nonpolar Covalent Bond
• A nonpolar covalent bond is formed between same atoms with similar electronegativities—the difference in electronegativity between bonded atoms is less than 0.5.
• A polar covalent bond is formed when atoms of slightly different electronegativities share electrons. The difference in electronegativity between bonded atoms is between 0.5 and 1.9.
• Metallic Bond

  This type of covalent bonding specifically occurs between atoms of metals, in which the valence of electrons are free to move through the lattice. This bond is formed via the attraction of the mobile electrons—referred to as sea of electrons—and the fixed positively charged metal ions.
• Basic information of Intramolecular Forces:

  1. Metallic Bond - Metal cations to delocalized electrons
  2. Ionic Bond - Cations to anions
  3. Polar Covalent Bond - Partially charged cation to partially charged anion
  4. Nonpolar Covalent Bond - Nuclei to shared electrons
• Relative strength of Intramolecular Forces:

  1. Metallic Bond - 1, strongest
  2. Ionic Bond - 2
  3. Polar Covalent Bond - 3
  4. Nonpolar Covalent Bond - 4, weakest
• Types of Intramolecular Forces:

  1. London Dispersion Forces (LDF)
  2. Dipole-Dipole Interaction
  3. Hydrogen Bonding
• London Dispersion Forces

  Result from the coulombic interactions between instantaneous dipoles. It is present between all molecules (and atoms) and are typically greater for heavier, more polarizable molecules and molecules with larger surface areas.
• Dipole-Dipole Forces

  Occur between molecules with permanent dipoles (i.e. polar molecules). For molecules of similar size and mass, the strength of these forces increases with increasing polarity. Polar molecules can also induce dipoles in nonpolar molecules, resulting in dipole-induced dipole forces.
• Hydrogen Bonding

  A special type of dipole-dipole interaction that occurs between the lone pair of a highly electronegative atom (typically N, O, or F). It can form between different molecules (intermolecular hydrogen bonding) or between different parts of the same molecule (intramolecular hydrogen bonding).
• Dipole-Dipole Forces

  Attractive forces that occur between polar molecules.
• London Dispersion Forces

  Intermolecular forces that occur between atoms and between nonpolar molecules as a result of the motion of electrons.
• Occurrence of Intermolecular Forces:

  1. Dipole-Dipole Forces - Partially oppositely charged ions
  2. Hydrogen Bonding - H atom and O, N, or F atom
  3. London Dispersion Forces - Temporary or induced dipoles
• Relative strength of intermolecular forces:

  1. Dipole-Dipole Forces - Strong
  2. Hydrogen Bonding - Strongest of the dipole-dipole attractions
  3. London Dispersion Forces - Weakest
• Melting

  Solid to Liquid
• Vaporization

  Liquid to Gas
• Ionization

  Gas to Plasma
• Sublimation

  Solid to Gas
• Deposition

  Gas to Solid
• Freezing

  Liquid to Solid
• Condensation

  Gas to Liquid
• Recombination

  Plasma to Gas
• Properties of Liquid:

  1. Viscosity
  2. Vapor Pressure
  3. Surface Tension
  4. Boiling Point
  5. Heats of Vaporization