Understanding
Secondary
Bonding
Dipole Forces, London Forces, and Hydrogen Bonding
By your ETutor
2025/03/17
1
Introduction to
Secondary Bonding
Definition:
Secondary bonds involve
intermolecular forces, which are
attractions between molecules.
Unlike primary bonds (ionic,
covalent, metallic), secondary
bonds do not involve the transfer
or sharing of electrons.
Importance:
Weaker than primary bonds but
critical in determining the
properties of materials at low
temperatures.
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Types of
Secondary
Bonding
Overview of Types:
Dipole Forces
London Forces
Hydrogen Bonding
Collective Name:
Van der Waals Forces (for
dipole and London forces)
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Dipole Forces
Definition:
Arise in polar molecules
with unequal distribution
of electrical charges.
Mechanism:
Example: Hydrogen Chloride
(HCl)
Each molecule forms a
dipole with a positive and
a negative end.
Figure 1.1 showing dipoles in HCl and their
Dipoles attract each other,
creating a force between
the molecules.
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London
Forces
Definition:
Attractive forces between
non-polar molecules.
Mechanism:
Due to the rapid motion of
electrons, temporary
dipoles can form.
Example: Methane (CH4)
Instantaneous dipoles lead
to attraction between
molecules.
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Figure 1.2
dipoles in CH4
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Hydrogen Bond
Definition:
A specific type of strong dipole
interaction involving hydrogen.
Mechanism:
Occurs in molecules where
hydrogen is covalently bonded to
highly electronegative atoms
(e.g., O, N, F).
Example: Water (H2O)
The positive charge of hydrogen
attracts the negative charge of
neighboring atoms.
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Importance of Secondary Bonds
Physical Properties:
Influence boiling and melting points.
Affect solubility and viscosity of substances.
Biological Significance:
Crucial in the structure of proteins and nucleic
acids (DNA).
Material Science:
Understanding secondary bonding is essential for
developing new materials.
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Reference
https://www.chemistrylearner.com/polarity/polari
ty-of-methane-ch4
https://chemistrybytes.com/intermolecularforces-of-attraction/
Maladzi, R.W. 2018. Mechanical Manufacturing
Engineering II: study guide for MTC2602.
Florida: University of South Africa
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