Ch 221
Hybridization Recitation Handout
General Process
1. Draw the Lewis Structure
2. Determine the VSEPR geometry
3. The number of “clouds” around the central atom = number of atomic orbitals (AO’s)
to mix (in order of increasing energy, e.g. starting with s, p, d)
4. The number of AO’s = the number of hybrids
5. Identify the number of sigma, pi and lone pairs
6. Refer to the following charts to determine hybrids and how to assign electrons to the
hybrid or unused p-orbitals:
7. Draw the orbital box diagrams using valence electrons only, promoting electrons as
needed
# clouds
(geometry)
2
(linear)
3
(trig.
planar)
4
(tetrahedral)
5
(trig.
bipyram.)
6
(octahedral)
number of
AO’s =
number of
hybrids
2
3
4
5
6
AO’s
required
s+p
s+p+p
s+p+p+p
resulting
hybrids
two sp
hybrids
three sp2
hybrids
four sp3
hybrids
five sp3d
hybrids
six sp3d2
hybrids
bond type(s)
, , 
, 



bond or lone
pairs
number of
electrons
s+p+p+p+d s+p+p+p+d+d
-bonds
lone pairs
-bonds
1 per hybrid
2 per hybrid
1 per unhybrized
p-orbital
Example 1 - -bonds and lone pair
NH3
Steps:
1. Draw the Lewis Structure
5 + 3(1) = 8/2 = 4 pairs
2. Determine the VSEPR geometry
ECG = 4 clouds = tetrahedral
MG = pyramidal
3. The number of “clouds” around the central atom = number of atomic orbitals (AO’s)
to mix (in order of increasing energy, e.g. starting with s, p, d)
4 clouds = 4 AO’s = s+p+p+p
4. The number of AO’s = the number of hybrids
s+p+p+p = four sp3 hybrids
5. Identify the number of sigma, pi and lone pairs
LP



one LP and three -bonds
6. Refer to the charts to determine hybrids and how to assign electrons to the hybrid or
unused p-orbitals:
In the four sp3 hybrids, one gets a lone pair, and the rest get one electron each
continued on the next page 
7. Draw the orbital box diagrams using valence electrons only, promoting electrons as
needed
N = 1s22s22p3
Example 2 - -bonds and a -bond
CH2O
Steps:
1. Draw the Lewis Structure
4 + 2(1) = 6/2 = 3 pairs
2. Determine the VSEPR geometry
ECG = 3 clouds = trigonal planar
MG = trigonal planar
3. The number of “clouds” around the central atom = number of atomic orbitals (AO’s)
to mix (in order of increasing energy, e.g. starting with s, p, d)
3 clouds = 3 AO’s = s+p+p
4. The number of AO’s = the number of hybrids
s+p+p = three sp2 hybrids
5. Identify the number of sigma, pi and lone pairs




three -bonds and one -bond
continued on the next page 
6. Refer to the charts to determine hybrids and how to assign electrons to the hybrid or
unused p-orbitals:
The three sp2 hybrids get one electron each
the unused p-orbital gets one electron for the one -bond
7. Draw the orbital box diagrams using valence electrons only, promoting electrons as
needed
C = 1s22s22p2
Example 3 - expanded octet, 4 -bonds and two lone pairs
SF4
Steps:
1. Draw the Lewis Structure
6 + 4(7) = 34/2 = 17 pairs, lone pairs on F not shown
for clarity
2. Determine the VSEPR geometry
ECG = 5 clouds = trigonal bipyramidal
MG = see-saw
3. The number of “clouds” around the central atom = number of atomic orbitals (AO’s)
to mix (in order of increasing energy, e.g. starting with s, p, d)
5 clouds = 5 AO’s = s+p+p+p+d
4. The number of AO’s = the number of hybrids
s+p+p+p+d = five sp3d hybrids
5. Identify the number of sigma, pi and lone pairs
four -bonds and one lone pair
6. Refer to the charts to determine hybrids and how to assign electrons to the hybrid or
unused p-orbitals:
Four sp3d hybrids get one electron each
the fifth hybrid gets a lone pair
continued on the next page 
7. Draw the orbital box diagrams using valence electrons only, promoting electrons as
needed
S = [Ne]3s23p4(3d) empty 3d orbitals are available for mixing