1) The charges are typically on the order of 10–10 esu; the distance 10–8 cm.
Figure 2.1 a) A ball-and-stick
model for hydrogen chloride. B)
A calculated electrostatic potential
map for hydrogen chloride showing
regions of relatively more negative
charge in red and more positive
charge in blue. Negative charge is
clearly localized near the chlorine,
resulting in a strong dipole moment
for the molecule.
2) The direction of polarity of a polar bond is symbolized by a vector quantity:
(positive end) (negative end) ⇒
HCl
3) The length of the arrow can be used to indicate the magnitude of the dipole
moment.
2.4 POLAR AND NONPOLAR MOLECULES
- The polarity (dipole moment) of a molecule is the vector sum of the dipole
moment of each individual polar bond.
Table 2.1 Dipole Moments of Some Simple Molecules
Formula μ (D) Formula μ (D)
H 2 0 CH 4 0
Cl 2 0 CH 3 Cl 1.87
HF 1.91 CH 2 Cl 2 1.55
HCl 1.08 CHCl 3 1.02
HBr 0.80 CCl 4 0
HI 0.42 NH 3 1.47
BF 3 0 NF 3 0.24
CO 2 0 H 2 O 1.85
