Molecular Geometry

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Warm up

• Draw the Lewis structure for ozone, O3.
• What does the word hybridization mean? Use your
  own words.

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Warm up
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Warm up
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Resonance
A resonance structure is a structure that occurs
when it is possible to draw two or more valid
electron dot structures. In the case of ozone,
neither structure actually exists, but rather the
actual bonding is an average of the two
structures.
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Resonance Ozone
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Resonance Phosphate
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Resonance Phosphate
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Warm up
Definition of hybridization .
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Hybridization

• Learn what a sigma bond looks like
• Learn what a pi bond looks like
• -Understand the concept of orbital hybridization
  and how it changes the bonding in an atom such as
  carbon

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Sigma Bond
When two atomic orbitals combine to form a bond
along the axis between two atoms we call it a
sigma bond (s)
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Sigma Bond
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Pi Bond
When two p orbitals combine side by side we say
they overlap to form a pi (P) bond Pi bonds
exist when we have double and triple bonds
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Pi Bond
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What does this all mean?
Single bond 1 sigma bond Double bond 1 sigma
and 1 pi bond Triple bond 1 sigma and 2 pi
bonds
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The electron structure of a carbon atom can be
written as
Based on this model, we would predict that carbon
atoms should form two covalent bonds??!!
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Instead carbon atoms almost always form 4 bonds.
Why????
Hybridization
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Hybridized Carbon Aufbau Diagram
Regular Carbon Aufbau Diagram
hybridization
1 s 3 p 4 sp3 (All 4 orbitals are now
equal at the 2nd energy level)
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Electrons must be distributed among the new
orbitals. Since these hybrid orbitals are equal
in energy, the electrons must distributed
according to Hunds Rule.
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4 sp3 orbitals
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4 sp3 orbitals bond with4 hydrogen atoms -
methane
Overlap here is known as sigma bond
sp3 carbon
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Lets predict what sp2 hybridization around a
carbon might look like?
Take out your white boards
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sp2 hybridization
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sp2 hybridizationcarbon double bond - ethene
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Can you predict sp geometry around a carbon?
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sp hybridization
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sp hybridizationcarbon triple bond - acetylene
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sp hybridizationcarbon triple bond - acetylene
234-236 in your text discusses these examples
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Summary
sp3 hybridization involves single-bonded
carbon sp2 hybridization involves double-bonded
carbon sp hybridization involves triple-bonded
carbon