Download Lab 2 VSEPR

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Lab 2: Molecular Structure and VSEPR
1. For each molecule or ion:
a. Column 1: Draw the Lewis dot structure.
b. Column 2: Build the model. Use a black ball for the central atom and a stick
with no ball on the end to represent a lone pair. For multiple bonds, use the thin,
flexible sticks, one for each pair of electrons shared. If the molecule has lone pairs
attached to the central atom, sketch the model in column 2. Otherwise, leave column
2 blank. Three-dimensional figures will need to be drawn with perspective so they
don’t look flat.
c. Column 3: Now, take out any lone pairs (so that your model only has atoms
and bonds). This shows the molecular geometry or shape around the central atom.
Sketch this model in column 3. (There should be no blanks in column 3.) Threedimensional figures will need to be drawn with perspective so they don’t look flat.
d. Column 4: Write the name of the geometry of the molecule or ion (linear, bent,
trigonal planar, trigonal pyramidal or tetrahedral). Refer to section 4.6 in your
textbook.
e. Column 5: Write the ideal bond angle. There are only three ideal angles, 180°,
120°, and 109.5°.
f. Column 6: Write whether the molecule or ion is polar or nonpolar. Polarity
depends on symmetry. Having different types of attached atoms decreases
symmetry, so that bond polarities don’t cancel out. Having lone pairs also decreases
symmetry, so that bond polarities don’t cancel out. When bond polarities cancel out,
the molecular polarity is zero and the molecule is nonpolar. When bond polarities
don’t cancel out, the molecular polarity is nonzero and the molecule is polar.
Edited by Nick Buker 12/18/08
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Column 1
Lewis Dot
Structure
Column 2
Sketch (with
lone pairs)
Column 3
Sketch (no lone
pairs)
Column 4
Molecular
Geometry
Column
5
Bond
Angles
Column 6
Polar or
Nonpolar
H2 O
NH3
CH4
N2
CO2
Edited by Nick Buker 12/18/08
2
Column 1
Lewis Dot
Structure
PO4-3
Column 2
Sketch (with
lone pairs)
Column 3
Sketch (no
lone pairs)
Column 4
Molecular
Geometry
Column 5
Bond
Angles
Column 6
Polar or
Nonpolar
NH4+
SO4-2
C2CL2
C2H4
Edited by Nick Buker 12/18/08
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