9/24/2017
The Nature of the Chemical
Covalent Bond
SECTION 4.2
LEARNING GOALS:
I WILL BE ABLE TO EXPLAIN THE 2 MAJOR
BOND TYPES
I WILL BE ABLE TO EXPLAIN HYBRIDIZATION
Valence Bond Theory
A half-filled orbital in one atom can overlap with
another half-filled orbital of a second atom to form a
new bonding orbital
The new bonding orbital from the overlap of atomic
orbitals contains a pair of electrons of opposite spin
The total number of electrons in the bonding orbital
must be two
When atoms bond, they arrange themselves in space to
achieve the maximum overlap of their half-filled
orbitals. Maximum overlap produces a bonding orbital
of lowest energy.
Hybrid Orbitals
Hybridization:
A theoretical process involving the combination of atomic
orbitals to create a new set of orbitals that take part in bonding
Hybrid orbitals only take place to form a new
molecule, they do not exist on their own.
See table 1 on pg. 234
Forms of Hybridization
Depending on the types of orbitals that
overlap you will get different shapes of
molecules:
sp hybridization occurs when an s and a p orbital
overlap –two sp combine result = linear
sp2 hybridization occurs when an s and 2 p orbitals
overlap, – three sp2 combine result = trigonal
planar
sp3 hybridization occurs when one s and three p
orbitals overlap – four sp3 combine result =
tetrahedral
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9/24/2017
Single Covalent Bonds
Single bonds form from the overlap of end to end
orbitals
The original bond formed between two atoms is
called a sigma (denoted by the Greek lowercase s, σ)
bond
Double and Triple Covalent Bonds
Double and Triple bonds form from the side to
side overlap of p orbitals over the sigma bond.
They are called pi (denoted by the Greek
lowercase p, π) bonds, a double bond has one π
bond and a triple bond has 2 π bonds
A Video Review
Double bonds:
https://www.youtube.com/watch?v=cPDptc0wUYI
Triple Bonds:
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9/24/2017
Today’s Tasks
Pg. 232 #4
Pg. 235 #8, 10, 11
Pg. 238 #18, 21 (propene has 1 double bond between
carbon atoms)
Pg. 239 #26 (draw structures…they all have triple
bonds)
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