Problem Set 3 
 
        The following problems will concentrate on Pauling's rules #1 and #2, and on
         ionic substitution
      1. In order to have confidence in the results of atomic structures obtained using Pauling's rule
         #1, the % ionic bond character may be important to know--determine the % ionic
         character for each single bond for each cation-anion for each mineral below--compare the overall % ionic
        character of the cation-O bond with that of the cation-S bond--which bond type (cation-O or cation-S)
         would probably give the better results (correct calculated CN) using Pauling's rules?

                                    a. NaCl       d. KCl       g. CuS
                                    b. CaF2       e. ZnS        h. CaCO3
                                    c. Fe2O3      f. As2S3      i. BaSO4

     2.  Do each of the following below;
            
          a. using Pauling's rule #1 (radius ratio-coordination number) and #2 (electrostatic valence)
              determine the atomic structures of each of the following minerals below--for correct structures
              and to save additional calculations, revisit the notes on the iso-meso-aniso-desmic 
              bond types--Make sure you surround each cation and anion with the appropriate kind 
              and quantity of  corresponding anion(s) and cation(s)
                      TiO2,   MgCO3,  PbSO4,   ZnCO3,  MnO2 ( Mn-O, CN=6),  NaNO3,  Mg2SiO4,
                             CaSO4 (formed at a low temperature), FeTiO3 , CaWO4 (formed at low temp), 
                       PbMoO4
          
           b. state the name (iso-, meso-, aniso-desmic) of each individual bond in the above min-
               erals

     3. Using the rules for ionic substitution, determine if Fe+2 can proxy for Si+4 in quartz, SiO2--
            List all reasons why you think such a substitution would or would not occur (probable, im-
         probable or possible)


     4. As in Number 3 above, determine the ability (strong-probably; weak-improbable; mod-
         erate-so so) of the following ions to proxy in the mineral--list all the reasons which played a
         a role in your answer
                
         a. Rb+1 for K+1 in orthoclase, KAlSi3O8         e. Sr+2 for Ba+2 in barite, BaSO4
         b. Ba+2 for Ca+2 in anorthite, CaAl2Si2O8         f.  Ti+4 for K+1 in orthoclase, KAlSi3O8
         c. Mn+2 for Fe+2 in olivine, Fe2SiO4                     g. Ba+2 for K+1 in orthoclase,    "
            d. Mn+2 for Ca+2 in anorthite, CaAl2Si2O8         h. Ga+3 for Al+3 in       "               "
                                                                                i   Ba+2 for Mn+2 " rhodochrosite, MnCO3, 
                                                                                j. Zn+2 for Ca+2 " CaAl2Si2O8 , anorthite--plagioclase

     5. What is important about the a. mesodesmic bond and b. anisodesmic bond?

     6.  Be able to discuss the nature of Pauling's Rules 1- 5. 

          

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