Lab - Covalent Bonds and Molecular Geometry
March 4, 2010
OHS Chemistry
To begin, complete the first two blank columns of the data table. For the column headed Bond Type use a
periodic table to determine the difference in electronegativity (ΔEn) and record it in the column. Then write
polar if any bond in the molecule is polar, otherwise write non-polar.
Using the molecule sets, assemble each molecule of Set I. Your chemistry teacher will quiz you for understanding
of the structures and check them off when correct. The model colors correspond to different elements:
H—yellow; O—red; C—black; N—sky blue; Cl—green; Br—dark blue; F—orange; S —mystery.
Under Shape indicate whether the molecule is linear, bent, pyramidal, or tetrahedral based on the central atom.
Under Molecule Type indicate whether the molecule as a whole is polar or non-polar. Under 3-D drawing
represent your molecule using lines, dashed lines and arrows to show the shape, including the positions of the
unshared pairs. Repeat the procedure for Set II.
Formula
Electron-dot
diagram
Bond
Type
Set 1
e.g
.
CCl4
1.
H2
2.
F2
3.
O2
4.
N2
5.
HBr
6.
C2H2
7.
CH3OH
Shape
Molecule
Type
3-D drawing of
Molecule
Formula
Electron-dot
formula
Bond
Type
Shape
Molecule
Type
3-D drawing
of Molecule
Set 2
8.
H2O
9.
CO2
10.
H2S
11.
NH3
12.
CH4
13.
H2O2
14.
CH3Cl
Questions:
1. Classify each of the following as: (1) ionic compound, (2) polar covalent molecule, (3) non-polar covalent molecule.
a. Br2
e. SiO2
b. MgCl2
f. N2
c. CCl4
g. CH2I2
d. HI
h. KBr
2. Both water and carbon dioxide are tri-atomic molecules (made up of three atoms). Explain why one is
polar and the other is non-polar.
Discuss and answer the following questions among members of your group for each
molecular model. Be sure every member of your group understands about each molecule.
I will be asking similar questions of you when I quiz you about the models.
1. What shape is the molecule?
2. What causes the molecule to be that shape?
3. Are the bonds polar or non-polar?
4. Is the molecule polar or non-polar? Explain why.
5. Which element is most electronegative in the molecule?
6. If the molecule is polar, where do the electrons spend most of their time?
7. If the molecule is polar, which end is positive/negative?
8. How would the molecule orient itself in space?
9. Which molecules have the strongest bonds?
Discuss and answer the following questions among members of your group for each
molecular model. Be sure every member of your group understands about each molecule.
I will be asking similar questions of you when I quiz you about the models.
1. What shape is the molecule?
2. What causes the molecule to be that shape?
3. Are the bonds polar or non-polar?
4. Is the molecule polar or non-polar? Explain why.
5. Which element is most electronegative in the molecule?
6. If the molecule is polar, where do the electrons spend most of their time?
7. If the molecule is polar, which end is positive/negative?
8. How would the molecule orient itself in space?
9. Which molecules have the strongest bonds?