Hybridization by 4T2tc7

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									              Periodic Properties: Groups 5A, 6A, and 7A
A.   Group 5A
     1. Elements and Symbols             Element Type               State
        a. N = Nitrogen                  Non-metal                  diatomic gas
        b. P = Phosphorous               Non-metal                  solid
        c. As = Arsenic                  Metalloid                  solid
        d. Sb = Antimony                 Metalloid                  solid
        e. Bi = Bismuth                  Metal                      solid

     2.   Some chemistry of the non-metal Group 5A Elements
          a. The elements tend to react to gain 3 electrons to be like noble gas
          b. These elements react with oxygen to form acidic compounds
             -   HNO3 = Nitric Acid              H3PO4 = Phosphoric Acid
             -   P4(s) + 5 O2(g) -----> P4O10(s)
             -   P4O10(s) + 6 H2O -----> 4 H3PO4(aq)
          c. Important Biological Elements
             -   N is a component of every amino acid (protein) and DNA
             -   P is a component of DNA
d. Phosphorous has more than one allotrope
    - Allotrope = stable solid phase
    - P4(s) is called “white phosphorous” is tetrahedral, and burns in air
    - Pred is called “red phosphorous” and is made of chains of P4
       tetrahedra
    - Pblack is called “black phosphorous” and is a crystalline solid




e. We will be reacting Red Phosphorous with Oxygen today in lab
   - Don’t bother with the bottle
   - Burn the phosphorous in the bunsen burner in the hood
   - Have a distilled water dampened piece of pH paper ready
   - Put the pH paper (green when damp) in the phosphorous smoke
   - If it turns red, that indicates the formation of acid
   - DON’T PUT HOT COMBUSTION SPOON INTO BOTTLE!!!
B. Group 6A
   1. Elements and Symbols           Element Type               State
       a. O = Oxygen                 Non-metal                  diatomic gas
       b. S = Sulfur                 Non-metal                  solid
       c. Se = Selenium              Non-metal                  solid
       d. Te = Tellurium             Metalloid                  solid
       e. Po = Polonium              Metalloid                  solid

   2. Some chemistry of the non-metal Group 5A Elements
       a. The elements tend to react to gain 2 electrons to be like noble gas
       b. 20% of the atmosphere and 50% of the crust is O (by mass)
       c. These elements react with oxygen to form acidic compounds
       d. Sulfuric Acid (H2SO4) is the largest volume chemical used in industry
           - S(s) + O2(g) -----> SO2(g)
           - SO2(g) + H2O(l) -----> H2SO3(aq) = sulfurous acid
       e. We will be burning S(s) in the hood to produce H2SO3
           - Use same procedure as for phosphorous
           - All waste P and S should be completely burned off of the spoon
   f. Sulfur has more than one Allotrope
       - Two allotropes of solid sulfur have 8-membered rings, but
          different crystal forms: “monoclinic” and “rhombic”
       - If liquid sulfur is cooled quickly, it solidifies as chains of sulfur
          atoms called “plastic sulfur”




monoclinic                     rhombic                      plastic
C. Group 7A = Halogens                                                (kJ/mol)
   1. Elements               Element Type      State                    E.A.
       a. F = Fluorine       Non-metal         diatomic gas, yellow     -328
       b. Cl = Chlorine      Non-metal         diatomic gas, yellow     -349
       c. Br = Bromine       Non-metal         diatomic liquid, brown   -325
       d. I = Iodine         Non-metal         diatomic solid, purple   -295
       e. At = Astatine      Non-metal         radioactive solid

   2. The chemistry of these elements is dominated by their need to add one e-
      2 Na(s) + Cl2(g) -----> 2 NaCl(s) + large amount of heat



     Sodium Reacts
     Violently with
     Chlorine
3. Electron Affinity = energy given off when a gaseous element gains an e-
   a. X(g) + e- -----> X-(g)
   b. Exothermic process because all elements accept e- due to + nucleus
   c. Adding e- is less favored down a group due to distance from nucleus
   d. Fluorine is so small, that repulsion from other electrons lowers its E.A.

4. Halogens with more favorable E.A. can take electrons from other halides
   a.              Cl2 + 2 Br- -----> 2 Cl- + Br2
   b. E.A:        -349                              -325
   c. Cl2 is reduced; Br- is oxidized
5. We will be studying this kind of reaction today in lab
   a. Prepare control samples:
       - I2/H2O + toluene = purple color of I2 in toluene
       - Br2/H2O + toluene = orange color of Br2 in toluene
       - Cl2/H2O + toluene = yellow color of Cl2 in toluene
                Cl2                        I2



                             Br2
b. Run all possible combinations of reactions between Cl/Br/I and
   observe the color of the toluene when finished
    Cl2 + Br- -----> yellow (Cl2) if no reaction; orange (Br2) if reaction
    Cl2 + I- ----->
    Br2 + Cl- ----->
    Br2 + I- -----> orange (Br2) if no reaction; purple (I2) if reaction
    I2 + Cl- ----->
    I2 + Br- ----->

c. Use parafilm to cover test tubes to shake them up
d. All halogen reactions go into a waste beaker in the hood
Incident: HF and Trifluoroacetic Acid Burn




Incident: HF Exposure

								
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