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Molecular Models Activity

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									 Molecular Models Activity
carbon tetrachloride     ammonia

methane                  hydrogen monochloride

water                    trichloromethane

ethane                   urea

ethyne                   propane

dihydrogen monosulfide   butane

carbon dioxide           nitrogen triiodide (video)



                                                supplies
Bonding and Shape of Molecules
Number      Number of       Covalent
of Bonds   Unshared Pairs   Structure   Shape             Examples


2               0            -Be-       Linear            BeCl2


                               B
3               0                       Trigonal planar   BF3


4               0              C        Tetrahedral       CH4, SiCl4
                              :



3               1              N        Pyramidal         NH3, PCl3
                              :




2               2              O:       Bent              H2O, H2S, SCl2
                Lewis Structures
1) Count up total number of valence electrons
2) Connect all atoms with single bonds
   - “multiple” atoms usually on outside
   - “single” atoms usually in center;
              C always in center,
             H always on outside.
                                                                 Gilbert Lewis
3) Complete octets on exterior atoms (not H, though)
   - no unpaired electrons (free radicals)
4) Check
   - valence electrons match with Step 1
   - all atoms (except H) have an octet; if not, try multiple bonds
   - any extra electrons? Put on central atom
            Carbon tetrachloride
                                  Cl
   Cl
Cl C Cl                           C
                           Cl                 Cl
   Cl                           Cl
                                     109.5o




     CCl4                 Tetrahedral geometry




Carbon tetrachloride – “carbon tet” had been used as dry cleaning solvent
                           because of its extreme non-polarity.
                       Methane
 H                             H

HCH                            C
 H                      H        109.5o   H
                             H
                     Tetrahedral geometry




Methane –The first member of the paraffin (alkane) hydrocarbons series.
         a.k.a. (marsh gas, CH4).
               Water
                d(-)
                       SO2

  Bent          O
geometry   H           H
                d(+)

           Polar molecule
                     Ethane
  C = 1s22s22p2
 H H
HC CH
 H H
Lewis dot notation             ball-and-stick




    C2H4
molecular formula


                          space-filling molecule
                     Ethane
 H H
HC CH
 H H
Lewis dot notation             ball-and-stick




    C2H6
molecular formula


                          space-filling molecule
                             Ethyne
       No octet                             6 electrons = triple bond
each C “feels” 6 electrons


HC CH                              HC CH
                                    Stable octet
       C2H2


HC CH
each C “feels” 7 carbons

     Ethyne – a.k.a. “acetylene”
Dihydrogen monosulfide
                  SO2


            S
       H          H

           Bent
       Carbon dioxide


O C O     O      C       O
                             O C O
               Linear
 CO2          geometry
         Ammonia
                  ..               ..
       N         N         H
                                   N
NH3   HH H   H
                       H
              Trigonal         H       107o   H
             Pyramidal             H
             geometry
       Amino Acids – Functional Groups


     Amine                Base Pair        Carboxylic Acid



     NH21-                                  R- COOH

               lose H+                H+
NH21-                        NH3               NH41+

                                                   H       1+




                                                   :
:




          1-
                             :
 N                           N                     N
      H                           H            H       H
                         H                         H
 H                            H

                 +
amine                    ammonia           ammonium ion
        Hydrogen monochloride

       H Cl
        HCl



d(+)                d(-)
                           HCl(g) + H2O(l)  HCl(aq)
                           hydrogen    water   hydrochloric
                            chloride               acid


   Polar molecule
          Trichloromethane

                                           d(+)

                     H
   H                                     H
Cl C Cl              C                Cl C Cl
   Cl         Cl        109.5o   Cl      Cl
                   Cl
  CHCl3                                   d(-)
             Tetrahedral geometry

                                      Polar molecule
                           Urea
                         NOT “di-urea”


             H                                      H
             N H                                    N H
 O C                                     O C
    N                                       N
      H                                       H
   H                                       H
                     CO(NH2)2

Urea – The first organic compound to be synthesized (Wohler, 1828).
           Propane
                         H
 H H H               H

                     C   C   C
                                 H



HC C CH         H
                     H   H   H
                                     H



 H H H

  C 3H 8
        Butane
 H H H H         H H H               H
HC C C CH   H-C-C-C-C-H
 H H H H         H H H               H

                         H           H
                     H           H
C4H10                C   C   C       C   H
                 H
                     H   H   H       H
        Nitrogen triiodide
                       ..
  N
I   I                  N
  I           I         107o     I
 NI3               I
                   Trigonal
                  Pyramidal
                  geometry

                            Video clip:

                            (slow motion)


                                            detonation of NI3
          Supplies
   15 black      (carbon)
    8 green      (chlorine and iodine)
    1 yellow     (sulfur)
    4 blue       (oxygen)
    4 red        (nitrogen)
   42 hydrogen   (hydrogen)
   67 bonds      (bonds)
 C          Cl         I         S       O N     H
   Cl              H
Cl C Cl           HCH                    O C O
   Cl              H                       CO2

  CCl4                     CH4

                    H                             S
HC CH                                            H H
     C2H2        Cl C Cl                         SH2


            H Cl    Cl
                                 CHCl3
                 HCl
 H H H H       H H H
HC C C CH     HC C CH
 H H H H       H H H


   N          N
 H HH       I   I
              I
Decomposition of Nitrogen Triiodide
Decomposition of Nitrogen Triiodide


                     N2
              NI3                 I2




   2 NI3(s)         N2(g) + 3 I2(g)
       H                            ..                       ..

       C                            N                        O
H        109.5o   H             H       107o   H               104.5o   H
    H                               H                      H
CH4, methane                    NH3, ammonia               H2O, water


    lone pair      ..
    electrons


                                                       O
                   O
                                                   O              O
        O                   O
                O3, ozone
                                              The VSEPR Model
                                         The Shapes of Some Simple ABn Molecules
                                                                                                            ..
                                                                       SO2
                                                                                    O
                                                                  S                                         N            F
       O            C            O                  O                  O                            F
                                                                                    S
                                                                                                                 F
                                                                             O              O
               Linear                                          Bent              Trigonal            Trigonal
                                                                                  planar            pyramidal
                                                                                                                 AB6
                                                                                    F                   F
                     F                                F                F                                         F
                                                                             F                  F
                                                                  Xe               P        F           S
       F            Cl            F
                                                        F              F     F                  F                    F

               T-shaped                                       Square                F                   F
                                                              planar
                                                                               Trigonal         Octahedral
                                                                             bipyramidal
Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 305
           Resources - Nomenclature
             Objectives                                             General Chemistry PP


Worksheet - binary cmpds: single charge cation                      Worksheet - binary compounds
Worksheet - ions in chemical formulas                               Worksheet - ions in chemical compounds

Worksheet - ionic cmpds: polyatomic ions w multiple-charge cation

Worksheet - ionic formulas (binary, polyatomic, transition)
                                                                    Worksheet - empirical and molecular
Worksheet - traditional system of nomenclature
                                                                    Worksheet - vocab (bonding)
Worksheet - covalent binary cmpds: non-metal - non-metal

Worksheet - ionic cmpds: polyatomic ions
                                                                    Activity - bonding pieces
Worksheet - ionic binary cmpds: multiple charge cation
                                                                    Activity - molecular models
Worksheet - errors in chemical formulas and nomenclature
                                                                    Activity - mole pattern
Worksheet - oxidation numbers and ionic cmpds
                                                                    Textbook - questions
Worksheet - names and formulas of cmpds

                                                                               Outline (general)

								
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