Chemical Bonding I: Lewis Theory Chapter

Chapter 9: Chemistry: A Molecular Approach, 2nd Ed.
Nivaldo Tro




Chemical Bonding I:
Lewis Theory

Wilson Okumu
Maseno University School of Medicine
Presentation Date: January 28, 2020
Copyright ♥ 2011 Pearson Education, Inc.

, Bonding Theories
• Explain how and why atoms attach
together to form molecules
• Explain why some combinations of atoms
are stable and others are not
!why is water H2O, not HO or H3O
• Can be used to predict the shapes of
molecules
• Can be used to predict the chemical and
physical properties of compounds


Tro: Chemistry: A Molecular Approach, 2/e Copyright ♥ 2011 Pearson Education, Inc.

, Lewis Bonding Theory
• One of the simplest bonding theories
is called Lewis Theory
• Lewis Theory emphasizes valence
electrons to explain bonding
• Using Lewis theory, we can draw
models — called Lewis structures
!Electron Dot Structures
• Lewis structures allow us to predict G.N. Lewis
many properties of molecules (1875-1946)
!such as molecular stability, shape, size,
polarity

Tro: Chemistry: A Molecular Approach, 2/e Copyright ♥ 2011 Pearson Education, Inc.

, Why Do Atoms Bond?
• Chemical bonds form because they lower the
potential energy between the charged particles that
compose atoms
• A chemical bond forms when the potential energy
of the bonded atoms is less than the potential
energy of the separate atoms
• To calculate this potential energy, you need to
consider the following interactions:
!nucleus—to—nucleus repulsions
!electron—to—electron repulsions
!nucleus—to—electron attractions
Tro: Chemistry: A Molecular Approach, 2/e Copyright ♥ 2011 Pearson Education, Inc.