1. V-B theory can’t explain some observations about
Hybridized Orbitals
V-B theory can’t explain some observations about
molecular compounds without the concept of
hybridized orbitals.
i.e., covalent (NM/NM) compounds

2. …the central atom SHOULD be… …but is ACTUALLY hybridized to be…
…the result
then being…
In…
(LS)
BeF2
2 hyb. sp orbs.
2 unhyb. 2p orbs. : Be F 2s 2p sp 2p B : F
BF3
3 hyb. sp2 orbs.
1 unhyb. 2p orb. 2s 2p
sp2 2p C H
CH4
4 hyb. sp3 orbs. 2s 2p
sp3
H2O O H :
4 hyb. sp3 orbs. 2s 2p
sp3 P : F
PF5
5 hyb. sp3d orbs.
4 unhyb. 3d orbs. 3s 3p 3d
sp3d 3d
XeF2
5 hyb. sp3d orbs.
4 unhyb. 5d orbs. : Xe F 5s 5p 5d
sp3d 5d : Xe F
6 hyb. sp3d2 orbs.
3 unhyb. 5d orbs.
XeF4 5s 5p 5d
sp3d2 5d

3. KEY: EDG  hybridization of central atom
linear  sp
trig. planar  sp2
tetrahedral  sp3
trig. bipyr.  sp3d
octahedral  sp3d2

4. sp hybridization
sp hybridization occurs when one s and one of the three p
orbitals hybridize. It results in the creation of two sp hybrid
orbitals (orange). The other two p orbitals (purple) are
unhybridized; they retain the “figure-8” or “dumbbell” shape.

5. .. Multiple Bonds s (sigma) bonds are bonds in which the e– density is
along the internuclear axis. N H ..
The bonds
in ammonia
are s bonds.
-- These are the single bonds we have
considered up to this point.
-- e.g., s-s, s-p, or p-p overlap,
and also p-sp hybrid overlap
sigma (s) = single
Multiple bonds result from the overlap of two p orbitals
(one from each atom) that are oriented perpendicularly
to the internuclear axis. These are p (pi) bonds.
pi, multiple, unhybridized

6. For each carbon atom, there
p bonds are generally weaker than s bonds because
p bonds have less overlap.
For ethene (C2H4)…
C=C – H C H
For each carbon atom, there
are 3 sp2 hybridized
orbitals; these form s
bonds ( ) with C or H.
Where unhybridized
orbitals overlap,
a p bond ( ) is formed.

7. Single bonds
are s bonds.
e.g., C2H6
Double bonds consist of
one s and one p.
e.g., C2H4
Triple bonds consist of
one s and two p.
e.g., C2H2

8. Experiments indicate that all
of C2H4’s atoms lie in the
same plane. This suggests
that p bonds introduce
rigidity (i.e., a reluctance
to rotate) into molecules.
-- p bonding does NOT occur with sp3 hybridization,
only sp and sp2
-- p bonding is more prevalent with small molecules
(e.g., C, N, O)
(Big atoms don’t allow enough
p-orb. overlap for p bonds to form.)

9. [ ] .. Delocalized p Bonding Localized p bonds are between…
two atoms only.
[ ] N =O O– .. O –
-- e.g.,
C2H2, C2H4, N2
Delocalized p bonds are
“smeared out” and
shared among…
> two atoms.
-- These are common for
molecules with…
resonance structures.
The nitrate ion (NO3–) has
delocalized electrons.
-- The electrons involved in
these bonds are delocalized electrons.

10. C H
Consider benzene, C6H6.
-- Each carbon atom is
___ hybridized.
sp2
-- This leaves...
a 2p
orbital on each C
that is oriented
to plane of m’cule.
-- 6 e– shared equally by 6 C atoms

11. [ ] .. .. .. Which of the following exhibit delocalized bonding? 24 e–
H–C–C–C–H O = .. –
H3C–C–CH3 O =
“NOPE.”
propanone
O–S=O ..
SO2
18 e–
“YEP.”
sulfur dioxide
(res.)
[ ] S –O O– .. O 2–
SO42–
32 e–
“NOPE.”
sulfate ion