chem

• Chemical bonding


  • A bond results from the attraction of nuclei for electrons
  • All atoms are trying to achieve a stable octet
• Major types of bonding

  • Ionic Bonding
  • Metallic Bonding
  • Covalent Bonding
• Ionic Bonding


  • Forms ionic compounds
  • Transfer of valence electrons
• Covalent Bonding


  • Forms molecules
  • Sharing of valence electrons
• Lewis-dot structure


  • Symbol represents the kernel of the atoms
  • Dots represent valence electrons
  • The ones place of the group number indicates the number of valence electrons on an atom
  • Draw a valence electron on each side before pairing them
• Atoms are trying to complete their valence shell
• The number of electrons the atoms needs is the total number of bonds they can make
• Drawing Lewis-dot structure


  1. Available - total number of electrons available for bonding

  2. Needed - total number of atoms needed to fill its valence shell

  3. Shared - two electrons are shared per bond

  4. Remaining - available to fill the valence shell
• Molecular formula


  Shows the kinds and numbers of atoms present in a molecule of a compound
• Structural formula


  Identifies the location of chemical bonds between the atoms of a molecule
• Rules for naming molecular compounds

  • The most "metallic" nonmetal element is written first
  • The most non metallic of the two nonmetals is written last in the formula
  • All binary molecular compounds end in - ide
• Prefixes


  • mono
  • di
  • tri
  • tetra
  • penta
  • hexa
  • hepta
  • octa
  • nona
  • deca
• If there is only one of the first element do not put (prefix) mono
• If the nonmetal starts with a vowel, drop the vowel ending from all prefixes except di and tri
• Three bond types


  • Ionic
  • Non-Polar Covalent
  • Polar Covalent
• Electronegativity difference


  • Ionic bonds - difference > 2.0
  • Polar Covalent bonds - difference is between .21 and 1.99
  • Non-Polar Covalent bonds - difference is < .20
• Ionic character


  • Refers to a bond's polarity
  • The closer the EN difference is to 2.0, the more POLAR its character
  • The closer the EN difference is to .20, the more NON-POLAR its character
• Non-polar molecules


  • Molecule is Equal on all sides
  • Symmetrical shape of molecule
• Polar molecules


  • Molecule is Not Equal on all sides
  • Not a symmetrical shape of molecule
• Shapes of molecules


  • Linear (straight line)
  • Trigonal planar
  • Tetrahedral
  • Bent
  • Trigonal pyramidal
• Intramolecular attraction


  Attractions within or inside molecules, also known as bonds
• Intermolecular attraction


  • Attractions between molecules
  • Hydrogen "bonding"
  • Dipole-Dipole
  • Induced Dipole (Dispersion Forces)
• Bond strength


  • Ionic
  • Covalent
  • Hydrogen
  • Dipole-Dipole
  • Induced Dipole