14.2 MULTIPLE BONDING AND HYBRIDIZATION
HYBRIDIZATION
How does carbon form 4 identical covalent bonds in methane, for example?
identical sp3 hybrids
4


. g . methane
e
 
ANIMATION: http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/hybrv18.swf
Definition: Hybridization is the _________________ of atomic orbitals to create new oribitals with properties
of those that were mixed. Hybridization is a theory used to explain how some atoms ____________.
Example: Hybridization and the Carbon atom
*There are three ways that carbon can undergo hybridization.
unhybridized
1. sp3 hybridized
2. sp2 hybridized
3. sp hybridized
SUMMARY:
1. one “s” mixed with three “p” orbitals = _______ _____ hybrids
2. one “s” mixed with two “p” orbitals = ________ ______ hybrids (one “p” orbital remains _____________)
3. one “s” mixed with one “p” orbital = ______ ____ hybrids (______ “p” orbital remains unhybridized)
*How would the above table differ for each of the following?
a) nitrogen ; b) oxygen ; c) beryllium ; d) boron ; *e) phosphorus ; *f) sulfur
TYPES OF COVALENT BONDS - Sigma (σ) and Pi (π) Bonds
TYPE OF
COVALENT
BOND
sigma(σ) bond
ORIENTATION OF
ORBITALS
ELECTRON DENSITY
TYPE(S) OF ORBITALS
INVOLVED
 ______-on-_____
overlap
 _____________ the internuclear axis(an imaginary line that
connects the nuclei)
 s + ____ overlap
 s + ____ overlap
 s + ____hybrid overlap
 sp3 + ____ hybrid overlap
pi (π) bond
 _____________
overlap
 __________ and __________
the inter-nuclear axis
 unhybridized ___-orbitals
Pi and Sigma Bonding Animations:
1. http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/bom5s2_6.swf
2. http://www.youtube.com/watch?v=ree49ge4VA4
MULTIPLE BONDING
e.g. Carbon Atom
1. SINGLE BOND
Methane(CH4):
2. DOUBLE BOND
Ethene(C2H4):
3. TRIPLE BOND
Ethyne(C2H2)
SUMMARY
TYPE OF BOND
Single covalent
Double covalent
Triple covalent
TYPE OF COVALENT BOND(S)
______ sigma
______ sigma and ______ pi
______ sigma and ______ pi
CARBON-CARBON MULTIPLE BONDING (BOND LENGTH AND BOND STRENGTH)
As the number of shared electrons increase, the attractive force increases, so the bond strength (bond energy / bond
enthalpy) ____________________. As the force of attraction increases the bond length ________________.
Type of Bond
Number of bonds
Bond length (pm)
1
2
3
0.154
0.134
0.120
C-C (σ)
C=C (σ + π)
C≡C (σ + π + π)
Bond Strength
(kJ mol-1)
348
612
837
 The strength of the sigma bond is 348 kJ mol-1.
 The strength of a pi bond is 612 – 348 = 264 kJ mol-1…weaker than a sigma bond
 Note that the double bond is not doubly strong, because the pi bond is weaker than the sigma bond. This is because
the electron density of a pi bond exists _____________ and _____________ the inter-nuclear axis.
PRACTICE: Identifying the Type of Hybridization:
Type of
Hybridization
sp3
sp2
sp
Type of
Bonds
Present
all single
VESPR Σ LPs
Notation and
BPs
AX4
all single
AX3E1
ammonia
all single
AX2E2
water
double and
two single
all single
AX3
AX3
ethene,
methanal
BCl3
double and
one single
triple or 2
double
bonds
2 single
AX2E1
SO2
AX2
Ethyne, CO2
AX2
BeCl2
Shape
Example
Bond Angle
methane
*What is probably the easiest way to determine hybridization type?
 Σ LPs and BPs = 4 = _________
 Σ LPs and BPs = 3 = _________
 Σ LPs and BPs = 2 = ________
Practice: Complete the following table for the atoms indicated in bold type. You should sketch the molecule in
the margin.
Molecule
CH3CH3
CH2CH2
O2
CH3CHO
CH3COCH3
CH3CN
N2
CH3NH2
Hybridization
Shape
Angle
Activity: Build molecular models of the following molecules while completing the table.
Molecular Structure
HybridBond Type of
Shape
ization
Angle Bond
1.
1-pentyne
2.
3.
4.
5.
1,2-butadiene
1.
2.
3.
4.
2-butyne
1.
2.
3.
4.
propanone
1.
2.
3.
4.
ethanoic acid
1.
2.
3.
4.