1.
Intermolecular
Forces of
Attraction
Prepared by: Jerome A. Bigael, Leyte Progressive High
School

2.
Intermolecular
forces:
This force holds
the molecules
together which
can be attractive
or repulsive.

3.
Inter-Ionic
Forces
On the other
hand, inter-
ionic forces
are forces that
hold ions
together.

4.
These intermolecular
forces are accountable
for the properties of
substances. Moreover,
intermolecular forces
also explain why
substances exist as
solids, liquids, or gases
at room temperature.

5.
Intermolecular and Inter-ionic Forces of
Attraction
Type of Interaction Interacting
Particles
Dispersi
on
All molecules
(especially
nonpolar molecules
Dipole-
dipole
Polar
molecules
Ion-
dipole
Ions and polar
molecules
Ion-
ion
Ions (cations and
anions)
Hydrogen
bond
N, O, or F bonded with H
atom

6.
4 Types of Intermolecular Forces (involving covalent
molecules)
1. Dipole-dipole
2. Ion-dipole
3. Dispersion forces
4. Hydrogen bond
The first three types are known as “Van der
Waals forces”. On the other hand, hydrogen
bond is a special type of dipole-dipole
interaction.

7.
Johannes Diderik van Der
Waals
was born on November
23, 1837 in Leyden, The
Netherlands.
 In his 1873 thesis, van
der Waals noted the non-
ideality of real gases and
attributed it to the
existence
of intermolecular
interactions.

8.
Dipole-dipole
forces
Dipole-dipole forces are
attractive forces existing
between polar molecules
(molecules that exhibit
dipole moment), such as
HCl.

9.
Because there is
unequal sharing of
electron between H
and Cl atoms, partial
positive and partial
negative poles exist
and are referred to as
a dipole.

10.
The more electronegative atom
becomes partially negative and has
most electron density, whereas the
least electronegative becomes
partially positive and has a lesser
electron density.

11.
Because poles of
opposite charges
attract, the partial
negative end (i.e.,Cl
atom) will be attracted
to the partial positive
end (i.e., H atom) of
another HCl molecule.
This force is weaker
than ionic and
hydrogen bonds.

12.
Sum
Up!
All polar molecules have a partial
negative end and partial positive end
which are attracted to each other.
The resulting forces are called dipole-
dipole forces. Dipole-dipole forces are
much weaker than ionic or covalent
bond.

13.
Ion-Dipole
Forces
Exist in the attraction between a charged
particle called ion (which can be a
positively charged cation or a negatively
charged anion) and a polar.
This exhibited in hydration, or the
interaction of water molecules with the
cations and anions of ionic compounds
dissolved in water.

14.
When NaCl is dissolved in water (H2O), NaCl will
dissociate
into sodium cations (Na+) and chlorine
anions (Cl-).
Because water is a polar molecule and has a partial
negative and partial positive poles, the Na+ will form an
ion-dipole interaction with the partial negative part of
water molecule (O), while Cl- will form an ion-dipole

15.
Sum
Up!
The ion force exists in the attraction between an ion
and a dipole molecule.
An ion is a charged atom because it has gained or
lost one or more electrons. It can be either
positively charged cation or negatively charged
anion.
The partial charges at the ends of the dipole

16.
Dispersion Forces or London
Forces
Are the weakest attractive force that are
formed due to the temporary dipoles
induced in non-polar molecules.
This force is also called induced-
dipole- induced-dipole attraction.

17.
Take for example, if there is an ion or a
polar molecule near an atom or non
polar molecule, there will be a
distortion of the nonpolar molecule
due to the force exerted by the ion or
the polar molecule.

18.
This distortion will result in temporary
dipoles in the nonpolar molecule which is
called induced dipole.
Induced dipole is the separation of the
positive and negative charges in a
nonpolar molecule due to its nearness of
an ion or polar molecule.

19.
On the other hand, when the induced
dipole is due to the the interaction
between an ion and non-polar
molecule, the interaction is called ion-
induced dipole interaction.

20.
When the induced dipole is due to the
interaction between a polar and
nonpolar molecule, the interaction is
called dipole- induced dipole
interaction.

21.
Sum
Up!
The London dispersion force is the weakest
intermolecular force because it has only a
temporary attractive force.
Dispersion force exist when the electrons in two
adjacent atoms attract and induce temporary
dipoles.
This forces is sometimes called induced-

22.
Hydrogen
Bond
A special type of dipole-dipole
interaction between the hydrogen
atom in a polar molecule and the
highly electronegative
atoms, N, O,and F in another
molecule.

23.
The water
molecule is a
very good
example of a
substance that
exhibits hydrogen
bonding.

24.
The electronegative atoms, like
OXYGEN, cause the bond to be
polar.
These atoms become slightly
negatively charged and the
hydrogen atom becomes slightly
positively charged. Thus, a dipole

25.
Sum
Up!
The hydrogen bond is an
attraction between a partial
positive hydrogen in a polar
molecule and a slightly negative
atom in another molecule.