Molecular Geometry
To determine the properties of molecules it is important to know
the ____________
molecular ____________
geometry . To predict molecular shape
chemists developed a theory called _______________
which
VSEPR
stands for:
Valence
Shell Electron
Pair _____________
Repulsion
_________ ______
__________ _____
VSEPR theory says that valence e- repulsion will cause atoms to
arrange themselves as far apart as possible. We will study ____
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basic molecular geometries with respect to a central (or single)
atom. It is necessary to distinguish between ____________
bonding pairs
of ____
e- and those not shared in a bond. “Unbonded” or
“unpaired” electrons are called _______
elone _______
pair ____
# of egroups
1 or 2
3
4
4
4
# of lone
pairs of e-
0
0
0
1
2
Angle
between
atoms
180°
120°
109.5°
~107°
~105°
Trigonal
Pyramid
Bent
Geometry
Trigonal Tetrahedral
Linear
Planar
Linear
Trigonal Planar
Tetrahedral
Trigonal Pyramidal
Bent
Stability
e- These valence shells OR
All atoms are surrounded by _____.
clouds OR _____________
orbitals full of electrons surrounding each
atom _________
repel each other because electron clouds are
____________ charged and like charges repel. Therefore, atoms
negatively
in a ______________will
molecule arrange themselves as ____________
far apart
minimize the repulsion
as possible from one another to _____________
and make the molecule stable.
Symmetry
Once the molecular geometry of a compound has been
symmetry can be determined. A
determined, the _______________
molecule can have ________
many or _______
no lines of symmetry.
Generally, lines of symmetry are found by cutting through the
_________
bond between two atoms.
Seeing symmetry will take practice!
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2/6 Molecular Geometry
Which of the following molecules has
only 1 lone pair of e- on its central atom?
Draw each e- dot structure in your notebook and
describe the molecular geometry (shape and angle)
of each molecule.
A) H2S
(S in the middle)
B) CH3F (C in the middle)
C) PF3
D) HBr
(P in the middle)
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2/5 Molecular Geometry
Which of the following molecules has
only 1 lone pair of e- on its central atom?
Draw each e- dot structure in your notebook and
describe the molecular geometry of each molecule
(name and angle)..
A) H2S
B) CH3F
C) PF3
D) HBr
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2/6 Symmetry
Which of the following molecules is unsymmetrical?
In your notebook, draw e- dot structures and label the molecular
geometry with bond angles as evidence of your answer.
A) BeCl2
B) H2CO
C) C2H2
D) OF2