chem u4

• Nonpolar covalent bond


  Bond between nonmetals, equal sharing of electrons, electronegativity difference ranges from 0.0 to 0.5
• Polar covalent bond


  Bond between nonmetals, unequal sharing of electrons, electronegativity difference is from 0.5 to 1.8, the difference creates poles
• Ionic bond


  Bond between a metal and a nonmetal, electrons are transferred, electronegativity difference more than 1.8
• Ionic bond

  • Electrostatic attraction between ions, exist as crystal lattice structures with alternating positive and negative regions
  • High melting point because of the strong attraction between ions
  • Must be melted or put in a solution to conduct
• Covalent bond


  • Sharing of electrons, not conductors in any state
  • Also called molecules
• Molecular covalent compounds


  • Liquids and gases at room temperature
  • Have a low melting point, so their intermolecular forces are weaker
• Network solids

  • Have no beginning or end of the atoms
  • Examples are graphite, diamond, and silicon dioxide
  • VERY high melting point
• Metallic bond


  • Have delocalized electrons, which are free to move around throughout
  • Good conductors, lustrous, and have a high melting point
  • Valence electrons form an electron cloud and move freely, making a sea of delocalized electrons, This holds the metal cations rigidly in place
• Lattice Energy


  The energy needed to separate and break the ionic bond apart
• Lattice Energy

  • A higher energy comes with a higher melting point
  • Affected by charge on ions (greater charge means higher LE)
  • Affected by radius (Smaller radius means higher LE)
• 3 special cases with transition metals

  • Zn 2+
  • Ag +
  • Cd 2+
• Acetate


  C2H3O2-
• Ammonium


  NH4+
• Carbonate


  CO3 2-
• Chromate


  CrO4 2-
• Dichromate


  Cr2O7 2-
• Cyanide


  CN-
• Hydroxide


  OH-
• Nitrate


  NO3-
• Permanganate


  MnO4-
• Sulfate


  SO4 2-
• Peroxide


  O2 2-
• Phosphate


  PO4 3-
• Oxalate


  C2O4 2-
• Thiosulfate


  S2O3 2-