Name:
Period:
Date:
Note Taking Guide: Part II: Covalent Bonding and Molecular Geometry
Essential Questions:
1. Okay, these structural diagrams are two dimensions. What do these molecules
really look like?
2. Do the bonds and lone pairs repel each other? And if yes, what does this do to the
shape of these molecules?
Molecular Geometry
 The shape of a molecule is determined by the ____________________________
located around the central atom.
 Electrons are negatively charged, so they repel each other.
 This causes molecules to take a shape with the __________________
__________________ between electron pairs.
 Theory is called __________________.
VSEPR
 Valence Shell Electron Pair Repulsion
 Predicts the three dimensional shape of molecules.
 The name tells you the theory:
o Valence shell = outside electrons.
o Electron Pair repulsion = electron pairs try to get __________________ as
possible from each other.
 Can determine the __________________
 To determine the shape, we look at the central atom and answer to questions.
1. How many atoms are bonded to the central atom?
2. How many lone pairs are on it?
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Molecular Geometry
____________________: One or two atoms bonded to the central atom and no lone pairs
____________________: Three atoms bonded to central atom with no lone pairs
____________________: Four atoms bonded to the central atom
____________________: Three atoms bonded to the central atom and one set of lone pair
electrons.
____________________: Two atoms bonded and two sets of lone pairs.
Atoms
bonded to
central atom
Number of
lone pairs
Shape
Bond angle
1 or 2
0
180 o
3
0
120 o
4
0
109.5 o
3
1
109.5 o
2
2
109.5o
Solving VSPER
How do we figure this out?
1. Calculate ____________________
2. Draw the ____________________
3. Determine the molecular shape (use above table to help you)
4. Draw the ____________________
How do we draw 3D?
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Let’s practice:
Molecular formula
Methane, CH4
Bond calculations
Structural diagram
Name & Molecular
shape
Wants:
Has:
Bonds
Ammonia NH3
Wants:
Has:
Bonds
Water, H2O
Wants:
Has:
Bonds
CS2
Wants:
Has:
Bonds
Now’s let’s build some models!
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NAMES:
DATE:
PERIOD:
MOLECULAR GEOMETRY ACTIVITY
With a partner, build the following molecules. Have the teacher check the molecule before moving to the next.
Black = carbon
Red = oxygen & sulfur
Blue = nitrogen & phosphorus
Short connector = single bonds
White = hydrogen
Green = halogens
Long connector = double or triple bonds
Let’s practice:
Molecular formula
Bond calculations
Structural Diagram
Name & Sketch the shape
(indicate # of bonds & # of
lone pairs on central atom)
Nitrogen triiodide, NI3
Wants:
Has:
Bonds:
Carbon tetrachloride,
CCl4
Wants:
Has:
Bonds:
Hydrogen Sulfide, H2S
Wants:
Has:
Bonds:
Formaldehyde , CH2O
Wants:
(carbon is the central atom)
Has:
Bonds:
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Teacher
initials
Hydrogen Fluoride, HF
Wants:
Has:
Bonds:
Dihydrogen oxide, H2O
Wants:
Has:
Bonds:
Phosphine, PH3
Wants:
Has:
Bonds:
Carbon dioxide, CO2
Wants:
(use the longer bonds to
make multiples )
Has:
Diatomic Nitrogen, N2
Wants:
(use the longer bonds to
make multiples )
Has:
Methanol, CH3OH
Wants:
(carbon is the central atom)
Has:
Bonds:
Bonds:
Bonds:
Sulfur trioxide, SO3
Wants:
Has:
Bonds:
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