BUILDING MOLECULAR MODELS (Seeing is believing?)                                                                                                                 NAME:_________________           

                                                                                                        Lab Partners:___________________

Using an available kit (either small plastic boxes or larger wooden models) build some molecules.  Let the sticks represent electron pairs either bonding pairs when there are spheres placed at either end or lone pairs of electrons.  In each case use a four-holed, “atom” to represent the central atom. For each molecule draw a Lewis Structure.  Build a model, draw a good picture (3-D if necessary) of what the molecule looks like, and  name the geometry or shape.

          a)  CCl₄                                            *b) SO₃^2-

          c)  NH₃                                             d) SO₃

          e)  H₂S                                             f)  CO₂

          g) HCN                                           h)  SO₂

Questions:

1.               For the pairs above in a row (i.e. a-b, c-d, e-f and g-h) state a difference between the compounds in terms of geometry.  Give a reason for this difference.

a-b

            c-d

            e-f

            g-h

2.               For each of the compounds constructed above, indicate whether the bonds are polar or not and whether the molecule is polar or not.

a.

            b.

            c.

            d.

            e.

            f.

            g.

            h.

3.               Formulate a rule in your own words that would help a friend be able to predict the geometry of a molecule.

4.               Formulate a rule in your own words that would help a friend be able to predict whether the molecule is polar or not.