Chapter 9 Notes by yurtgc548

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									Chapter 8 Notes

 Mr Nelson 2010
Chemical Bonds
    • Three basic types of bonds
      – Ionic
         • Electrostatic attraction between
           ions


      – Covalent
         • Sharing of electrons


      – Metallic
         • Metal atoms bonded to several
           other atoms
   Ionic Compounds – Review
• Made up of ions
  – Cations (+) & Anions (-)
  – Metals & Nonmetals (or polyatomic ions)


• Exchange of electrons

• Charges Balance
     Molecular Compounds – Intro
• No ions
  – Charges will not balance
  – Composed of two nonmetals


• Sharing of electrons
  – Covalent bonding


• Naming is based on prefixes
Nomenclature of Binary Compounds
              • If both elements are nonmetals
                we must use prefixes.

              • The 1st element only gets a
                prefix if it is greater than 1.

              • 2nd element always gets a
                prefix and change the ending
                to -ide
Nomenclature of Binary
    Compounds
         • Example of a molecular comp:

         • CO2



         • CO


         • CCl4
         Practice
• PCl5      dihydrogen monoxide

• SF6       carbon trichloride

• N 2O      disulfur hexoxide

• NO2       nitrogen triiodide
                 Naming Acids
• An acid is any compound that starts with a
  hydrogen



• When naming an acid:
  – 1st locate the anion (- charge)
             Acid Nomenclature
• If the anion in the acid ends in –ide (not PI)
• change the ending to -ic acid and add the
  prefix hydro-

          hydro________ic acid

  – HCl
             Acid Nomenclature
• If the anion in the acid ends in –ate (all PI’s)
• change the ending to -ic acid.

          ___________ic acid

  – HClO3
             Acid Nomenclature
• If the anion in the acid ends in –ite (all PI’s)
• change the ending to -ous acid.

          _________ous acid


  – HClO2
              Acids – Finishing Up
• If you have the name and need to find the formula
   – Example: Acetic Acid
   – Cross off the –ic and add at –ate
                        -
   – Acetate! = C2H3O2

• Finish by adding the correct # of H’s (1 for every negative)

• HC2H3O2 is acetic acid J
            Warm Up
•   HBr           Chlorous Acid
•   FeS           Copper(I) fluoride
•   PBr5          dinitrogen dioxide
•   K2SO4         nitrogen monoxide
•   CCl4          hydroiodic acid
•   HNO3          potassium nitrate
•   LiCl          phosphoric acid
Covalent Bonding
   • Covalent bond – atoms share electrons



   • There are several electrostatic
     interactions in these bonds:
      – Attractions between electrons and nuclei
      – Repulsions between electrons
      – Repulsions between nuclei
          Lewis Dot Structures
• ONLY Valence (outer) electrons are involved.

• Lewis dot structures can be drawn for:
  – atoms
  – molecules


• Lewis dot structures show structure of a
  molecule, and help predict shape.
Steps to Writing Lewis Structures
                  1. Find the sum of valence

   PCl3              electrons of all atoms in
                     the polyatomic ion or
                     molecule.


  5 + 3(7) = 26
        Writing Lewis Structures
                               2. Arrange element
                                  symbols to show how
                                  atoms are connected –
                                  show electrons as dots.
                                     Draw in the valence
                                     electrons of each of the
                                     atoms

Keep track of the electrons:
        Writing Lewis Structures
                               3. Connect the lines to
                                  form single bonds.
                                  v 1 line = 2 electrons




Keep track of the electrons:
        Writing Lewis Structures
                               4. Finish by checking
                                  for octets.
                                 v Hydrogen only needs
                                   2 electrons to be
                                   happy




Keep track of the electrons:
         Writing Lewis Structures
5. If the central atom does not have an octet…

   …form multiple bonds until it does. Example: HCN
                Exceptions!
• Boron and Aluminum are okay with only 6 e-
  around them
  – BF3
                       Exceptions
• If the Lewis Dot Structure you are drawing is an ion:
  – Use [] and specify the charge
  – Add or subtract electrons
     • Positive charges take away electrons
     • Negative charges add electrons


• Example: Br-

								
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