Chemistry Reference
In-Depth Information
Figure 9.7 Overlap between two sp bond hybrids along the bond direction
.
For the carbon atom, promotion of an electron from 2s to 2p
increases its covalency from 2 to 4, giving the possibility of forming
four equivalent sp
3
hybrids directed towards the vertices of a tetra-
hedron, making an interhybrid angle of 109.5
. The energy expended
for promoting electrons is largely recovered by the formation of two
additional strong single bonds.
.
Hybridization increases overlap between the AOs forming the bond,
yielding a stronger bond (more correctly, it increases the exchange-
overlap component of the bond energy).
The interhybrid overlap between two sp hybrids b
A
and b
B
is shown in
the bottom part of Figure 9.7. Assuming positive all elementary overlaps
between s and p
s
AOs, the overlap between two general sp hybrids
making an angle 2
u
with respect to the bond direction z is
S
bb
¼h
b
A
j
b
B
i
¼
S
ss
cos
2
vþð
S
ss
cos
2
2
uþ
S
pp
sin
2
2
uÞ
sin
2
vþ
S
s
s
cos2
u
sin2
v
ð
9
:
61
Þ
