KMT

• Kinetic Molecular Theory

  explains the properties of gas, solids, and liquids in terms of intermolecular forces of attraction and the kinetic energy of the individual particles.
• The theory states that:

  1. All matter is made of tiny particles. These particles are in constant motion.

  2. The speed of particles is proportional to temperature.

  3. Solids, liquids, and gases differ in distances between particles, freedom of motion of particles, and the extent to which the particles interact.
• volume/ shape

  solid : Fixed, regardless of size

  And the shape of the container

  liquid : Fixed volume; assumes

  The shape of the occupied part of container.

  gas : Assumes volume and

  shape of container
• compressibility:

  solid : Almost incompressible

  liquid : Slightly compressible but cannot be easily compressed.

  gas : Easy to compress
• density

  solid : high

  liquid : high

  gas : low
• liquids : higher collision rate than gases
• liquids - higher collision rate than gases
• gases - higher elastic rate
• forces of attraction - any type of force that causes objects to come together, even if those objects are not close or touching each other
• types of forces of attraction

  • intramolecular
  • intermolecular
• Generally, intermolecular forces are weaker than intramolecular forces
• Intramolecular Forces

  [METALLIC, IONIC & COVALENT]
• Metallic Bond

  consists of positive ions and a sea of electrons, which is free to move about among the ions.

  Ex: Fe, Mg, Li
• Ionic Bond

  electrostatic attraction between two oppositely charged ion

  Ex: NaCl, MgO
• Covalent Bond

  A bond that involves the sharing of electrons to form electron pairs between atoms.

  Ex: H2, CO2, H2O
• COVALENT BOND (Based on Bond Polarity)

  • polar
  • non polar
• POLAR

  covalent compounds with uneven sharing of electrons
• NON-POLAR

  covalent compounds with equal sharing of electrons
• Ways to Determine the Bond Polarity

  • Difference in Electronegativity
  • dipole moment
• Dipole Moment

  the product of the charges at one center multiplied to the distance between the positive and the negative centers
• Electronegativity

  The ability of an atom to attract itself to the electrons in a chemical bond
• Elements with high electronegativity have a greater tendency to attract electrons than the elements with low electronegativity
• If the electronegativity difference has a value of:

  0 - non polar covalent

  0.1 - 1.8 polar covalent

  > 1.9 - ionic
• Dipole moments occur when there is a separation of charge. A quantitative measure of the polarity of a bond.
• The higher the difference in electronegativity the larger the dipole moment
• The shift of electron density is symbolized by placing a crossed arrow:

  
• Ion- Dipole Bond

  attractive forces between an ion and a polar molecule
• Dipole refers to a bond or molecule whose ends have opposite charges
• Van der Waals Forces

  intermolecular forces, distance affects their strength , weaker than intramolecular forces
• types of VDW forces

  • hydrogen bonding (strongest)
  • dipole-dipole interaction
  • london dispersion forces (weak)
• London Dispersion

  Temporary attractions between molecules occurs when the electrons around a molecule are unevenly distributed causing a temporary dipole.
• Dipole- Dipole Bond

  occurs between polar covalent molecules where one part of the molecule has a partial positive charge and the other part a partial negative charge
• Hydrogen Bond

  attraction between a highly electronegative atom (N, O, and F) and a hydrogen atom

  Ex: H2O molecule
• intermolecular forces

  • ion - dipole bond
  • Van der Waals Forces
  • London Dispersion
  • dipole - dipole bond
  • hydrogen bond
• intramolecular - Attractive forces bet. atoms and molecules
• intermolecular - attractive forces between molecules