+
Bonding Part III
Unit 5: BondingMrs. Callender
V SE P
R
+Lesson Essential Question:
How do I Predict Molecular Shape?
+VSEPR stands for….ValenceShellElectronPairRepulsion
The structure around a given atom is determined principally by minimizing electron pair repulsions.
+ How to predict a VSEPR Structure?
1. Draw a Lewis Dot Structure
2. Put pairs as far apart as possible.
3. Determine position of atoms from the way the electron pairs are shared and unshared.
4. Determine the name of the molecular structure from positions of the atoms and electron pairs.
+ Electron Pair Count and Geometry
A number of possibilities – seven pairs on the central atom.
Linear – two pairs on the central atom.
Trigonal – three pairs on the central atom.
Trigonal Bipyramidal – five pairs on the central
atom.
Tetrahedral – four pairs on the central atom.
Octahedral – six pairs on the central atom.
+ How do I figure out the geometry?
Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
2 Linear,180o
2 BP Linear
BeCl2
Be– 2 valence e-2 Cl – 14 valence e-Total = 16 valence e- C
lBe
Cl
Two Bonding Pair (BP) of electrons and no unbonded pair of electrons fits the Linear criteria.
AX2E0
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
3 Trigonal Planar,120o
3 BP Trigonal Planar
BF3
B– 3 valence e-3 F – 21 valence e-Total = 24 valence e- F B F
FThree Bonding Pair (BP) of electrons and no unbonded pair of electrons fits the Trigonal Planar criteria.AX3E0
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
3 Trigonal Planar,120o
2 BP1 LP
BentSO2
S – 6 valence e-2 O– 12 valence e-Total = 18 valence e- O S O
This structure has resonance so the bonds between the S and O represent 2 Bonding Pairs (BP) of electrons.
One Lone Pair (LP) of electrons.
AX2E1
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
4 Tetrahedral109.5o 4 BP
Tetrahedral CH4
C – 4 valence e-4 H– 4 valence e-Total = 8 valence e-
H CH
HH
4 Bonding Pairs of electrons and no Lone Pair of electrons has this compound as a Tetrahedral.
AX4E0
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
4 Tetrahedral109.5o 3 BP
1 LP
Trigonal Pyramidal NH3
N – 5 valence e-3 H– 3 valence e-Total = 8 valence e-
H N HH
3 Bonding Pairs of electrons and one Lone Pair of electrons has this compound as a Trigonal Pyramidal.
AX3E1
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
4 Tetrahedral109.5o 2 BP
2 LP
BentH2O
2 H – 2 valence e-O– 6 valence e-Total = 8 valence e- H O H
3 Bonding Pairs of electrons and Two Lone Pair of electrons has this compound as a Trigonal Pyramidal.AX2E2
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
5 Trigonal Bipyramida
l120o, 90o
5 BPTrigonal
BipyramidalPCl5
P – 5 valence e- 5 Cl – 35 valence e-Total = 40 valence e-
Cl
PCl
Cl C
lCl
v
5 Bonding Pairs of electrons and no Lone Pair of electrons has this compound as a Trigonal Bipyramidal
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX5E0
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
5 Trigonal Bipyramida
l120o, 90o
4 BP1 LP
See-SawSF4
S – 6 valence e-4 F – 28 valence e-Total = 34 valence e-
F SF
FF
v
4 Bonding Pairs of electrons and One Lone Pair of electrons has this compound as a See Saw
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX4E1
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
5 Trigonal Bipyramida
l120o, 90o
3 BP2 LP
T-ShapedICl3
I – 7 valence e-3 Cl – 21 valence e-Total = 28 valence e-
Cl
ICl
Cl
3 Bonding Pairs of electrons and Two Lone Pair of electrons has this compound as T-Shaped.
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX3E2
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
5 Trigonal Bipyramida
l120o, 90o
2 BP3 LP
LinearI3-1
3 I – 21 valence e--1 charge – 1 valence e-Total = 22 valence e-
I I I 2 Bonding Pairs of electrons and Three Lone Pair of electrons has this compound as Linear.
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX2E3
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
6 Octahedral90o 6 BP
Octahedral SF6
S – 6 valence e-6 F – 42 valence e-Total = 48 valence e-
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
F S F F F
F F 6 Bonding Pairs of electrons and no Lone Pair of electrons has this compound as an Octahedral.AX6E0
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
6 Octahedral90o 5 BP
1 LP
Square Pyramid
IF5
I – 7 valence e-5 F – 35 valence e-Total = 42 valence e-
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
F I F F F
F 5 Bonding Pairs of electrons and One Lone Pair of electrons has this compound as a Square Pyramidal.AX5E1
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
6 Octahedral90o 4 BP
2 LP
Square Planar
XeF4
Xe – 8 valence e-4 F – 28 valence e-Total = 32 valence e-
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
FXe
F F F
4 Bonding Pairs of electrons and Two Lone Pair of electrons has this compound as a Square PlanarAX4E2
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
7 Pentagonal Bipyramid 7 BP
Pentagonal Bipyramid
IF7
I – 7 valence e-7 F – 49 valence e-Total = 56 valence e-
Some elements can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX7E0
FIF
F F
F F F
7 Bonding Pairs of electrons and No Lone Pair electrons has this compound as a Pentagonal Bipyramid.
+Electron Pair #
GeometricalArrangement
Types of e- Pairs
Molecular Shapes Ex’s Ball and Stick
Model
7 Pentagonal Bipyramid 6 BP
1 LP
Pentagonal Pyramidal
IOF5-2
I – 7 valence e-5 F – 35 valence e-O – 6 valence e--2 charge – 2 valence e-Total = 50 valence e-Some elements
can have EXPANDED Octets which means they can have more than the eight electrons around the central atom.
AX6E1
IO
F F
F F F
6 Bonding Pairs of electrons and One Lone Pair electrons has this compound as a Pentagonal Pyramidal.
+Dotted Line and Wedge Model
Linear AX2E0
Trigonal Planar AX3E0
Bent AX2E1
+Dotted Line and Wedge Model
Tetrahedral AX4E0
Trigonal Pyramidal AX3E1
Bent AX2E2
+Dotted Line and Wedge Model
Octahedral AX6E0
Square Pyramid AX5E1
Square Planar AX4E2
+Dotted Line and Wedge Model
Pentagonal Bipyramid AX7E0
Pentagonal Pyramid AX6E1