Transcript VSEPR and Hybrids

VSEPR
A little bit of Chapter 9
VSEPR Theory
V alence
S hell
E lectron
P air
R epulsion
• repulsion between pairs of
electrons around an atom
cause them to be as far apart
as possible
• used to predict the geometry
of molecules
Molecular Shapes
• diatomic molecules will always be linear
• all other molecules can have different shapes
based on the number of charge clouds around
the central atom
• charge clouds include:
– bonding pairs
– lone pairs
What do you need to know?
• the geometrical shapes compounds will form
based on bonds & lone pairs
• The bond angles for the main geometries
(those with no lone pairs)
• the next slide sums it all up…
Polarity
For a compound to be polar, 2 qualifications
must be met:
1. the bonds must be polar AND
2. the overall geometry must be asymmetrical
Think vectors from physics 
How can bonds even happen?
• bonding electrons are usually on different
energy levels and different sub-levels
• to even things out, atoms form hybrid orbitals
(like the mutts of the orbital world)
• For more info about hybrid orbitals, we are
going to watch a little video…
Hybridization Video
Sigma and Pi bonds
• all single bonds are sigma
• all double bonds are combo sigma and pi
bonds
• all triple bonds are combo one sigma and 2 pi
bonds
Practice
Consider the chemical species IF5 & IF4+
a) Draw the Lewis structure and make a rough 3D
sketch of each species.
b) Identify the orbital hybridization and the VSEPR
geometry of each.
c) Identify the approximate bond angles of each
species.
d) Predict which, if any, is a polar species. Justify your
answer.
e) Predict the most probable oxidation number of the
iodine atom in each species.
f) Would you expect the conversion of IF5 to IF4+ to be
endo- or exothermic. Explain.