Chapter 13
Molecular Shapes
Methane (CH4)
Molecular Shape
• The shape of a molecule is determined by
the fact that the regions of high electron
density (bonds and lone pairs) around a
central atom try to get as far from each
other as possible.
H2S
• Dihydrogen monosulfide or just hydrogen
sulfide is also known as sewer gas. This
colorless, toxic and flammable gas is
responsible for the foul odor of rotten eggs.
H
••
S
••
H
H2S
• Dihydrogen monosulfide or just hydrogen
sulfide is also known as sewer gas. This
colorless, toxic and flammable gas is
responsible for the foul odor of rotten eggs.
S
H
H
Steps in Determining Molecular Shape
1. Draw the Lewis Structure for the
Molecule.
2. Count the number of atoms attached to
the central atom.
3. Count the number of lone pairs attached
to the central atom.
4. Use your counts on steps 2 and 3 to
determine the shape of the molecule.
H2
HCN
H2S
S
H
H
SO2
CH4
NO3-
SOCl2
Homework
 Worksheet Chapter 13.