NOTES-56A: INTERMOLECULAR FORCES (STUDENT)
DATE ________________
CHEM 110 (BEAMER)
NOTES-56A: Intermolecular Forces-01
XXX
XXXxxx
Types of Intermolecular Forces
General Information

You will need Appendix 7 – Electronegativity Values Table

Textbook: 11.2
I.
Intermolecular Forces

The two particles can be

Example of the same particle:

Example of the different particles:
II.
Types of Intermolecular Forces (CHEM 110-level)

Description of Two Particles
Name of Intermolecular Force
Relative Strength
two non-polar molecules
dispersion forces
weakest
two polar molecules
dipole-dipole
special
hydrogen bonding
one polar molecule, one ion
dipole-ion
one H-bonding particle, one ion
hydrogen bonding-ion
two ions
ion-ion
(CHEM 120 level)
(covalent network solid)

or
and
and
strongest
Review of Polarity, C-H, N-H, O-H, and C-O
Page 1 of 5
DATE ________________
NOTES-56A: INTERMOLECULAR FORCES (STUDENT)
CHEM 110 (BEAMER)
III.
.
C = 2.55 H = 2.20 Difference =


Examples:
F2
F2



so,
All substances will have dispersion forces. If any other forces are present, dispersion forces don’t even
register!
Page 2 of 5
DATE ________________
NOTES-56A: INTERMOLECULAR FORCES (STUDENT)
CHEM 110 (BEAMER)
IV.

Permanent partial charges, called

Indicated by the symbols

Example:
ICl (I = 2.66, Cl = 3.16)
, due to difference in electronegativity.
ICl
IV.

One electronegative atom with at least one lone pair:

The electronegative atom must be covalently bonded to a


Examples:
H2O (H = 2.20, O = 3.44)
H2O
NH3 (H = 2.20, N = 3.04)
NH3
These are stronger than normal dipole-dipole forces, due to
.
Page 3 of 5
DATE ________________
NOTES-56A: INTERMOLECULAR FORCES (STUDENT)
CHEM 110 (BEAMER)
V.

Example:
H2CO (draw structure for students, C-O bond important)
K+
VI.

Examples:
H2O
K+
(K = 0.82) K+ and F– (F = 3.98)
(K = 0.82) K+ and I– (I = 2.66)
VI.

Examples:
Page 4 of 5
DATE ________________
NOTES-56A: INTERMOLECULAR FORCES (STUDENT)
CHEM 110 (BEAMER)
Sample Questions
For the following molecules, write the strongest intermolecular force present. Then rank the forces in order of weakest
(1) to strongest (6).

CH4 and CH4

Mg2+ + NH3

H2CO and Li+

O2– and K+

C3H8 and C3H8

CO and CO
Page 5 of 5