LECTURE 7.1
LECTURE OUTLINE
Weekly Deadlines
 Bonding and the Periodic Table

Lesson#
Name
7
Structure, Part 3: Bonding, Crystal Struct ures, and
Properties
Lectures
Monday: Le cture 7.1 Bonding and the Periodic Table
Wednesday: Lecture 7.2 The Structure of Polymers
Required Book Reading 1
(For the End -of-Lesson
Quiz)
Required Book Reading 2
(For the Lesson 08 Pract ice
Quiz)
Part D: The Material Science Tetrahedron I: Structure
Chapters 17, 18, 19 and 20
Animations
Ian Harrison: “St ates of Matter”
“Polymer Synthesis”
Biographies
Mineral of t he Week
Camera -Ready Review
Article (CRRA)
Nothing
Pract ice Quiz
Practice quizzes (5 questions each) are availa ble. Questions
are sim ilar to those in the main qu iz database. There are
also prac tice quizzes in Perception. Questions are simi lar to
those in the main quiz database. A compl ete “prototype”
end-of-lesson (practice) quiz is found in the Lesson 07
Lecture Notes folder.
End-of-Lesson Quiz
Quiz 7 will consist of 30 q uestions for a total of 70 points.
Quizzes a re “in dividu ali zed” but questio ns are taken from a
large d atabase.
Part D: The Materials Sc ience Tetrahedron I: Structure
Chapters 22, 23, and 24, and the Epilog ue to Part D
The m aterial covered will be the book reading and
anim ations.
LESSON 07: BONDING
AND THE PERIODIC
TABLE
Ionic Bonding
Covalent Bonding
Metallic Bonding
van der Waals Bonding
Hydrogen Bonding
PRIMARY AND SECONDARY
BONDS
Primary Bonds: Chemical (strong) bonding,
involves the transfer or sharing of electrons:
ionic, covalent, or metallic bonds.
 Secondary Bonds: Physical (weak) bonding,
does not involve the transfer or sharing of
electrons: hydrogen and van der Waals
bonds.

DIRECTIONAL AND NONDIRECTIONAL BONDS
Directional Bonds: Single or multiple bonds,
which are localized and occur at fixed
angles with respect to each other.
 Non-Directional Bonds: Bonding is equally
probable at all angles. The bond is not
localized to a specific direction.

THE THREE PRIMARY OR
STRONG BONDS
Metal to Non-Metal: Ionic (Chapter 15)
 Non-Metal to Non-Metal: Covalent (Chapter
16)
 Metal to Metal: Metallic (Chapter 17)

THE SECONDARY OR WEAK
BONDS
van der Waals: Fluctuating dipoles (Chapter
18)
 Hydrogen: Develops between “electropositive”
and “electronegative” elements. Permanent
dipoles (Chapter 19)

THE IONIC BOND
The establishment of the “noble gas
configuration” by electron transfer from
metallic atoms to non-metallic atoms. The
electrostatic bond is thus formed between
positively charged metallic ions (cations) and
negatively charged non-metallic ions (anions).
 Ionic bonds are non-directional.

THE IONIC BOND
Ionic Bond: Arises from the electrostatic attraction
between cations and anions. Because the cations are
everywhere positive and the anions are everywhere
negative, the bond is non-directional.
_
+
THE IONIC BOND

Always produces compounds. Examples include
NaCl (common salt), Na2O (natron), and MgO
(magnesium oxide), where one species is metallic
(the cation) and is from Groups I–III, or the transition
metals, and the other species is non-metallic (the
anion)* and is from Groups V–VII. Most importantly,
ionically bonded solids are non-metallic and
inorganic—they are ceramics.

* A Negative ION
THE COVALENT BOND
The attainment of the "magical octet" of outer
shell electrons by atoms sharing pairs of
valence electrons.
 Each shared electron pair constitutes a single
bond.
 Covalent bonds are directional.
 Covalently bonded materials are non-metallic.

THE COVALENT BOND
Covalent Bond: Arises from the electrostatic attraction
between cations/cation cores and shared electron pairs.
The electrons are said to be localized, because they are
confined, primarily between adjacent cations.
Hence, the covalent bond is directional.
THE COVALENT BOND
Occurs in non-metallic elements (Groups IV–
VII) to form, for example, network solids
(diamond carbon and silicon) and molecular
gases (hydrogen, oxygen).
 Covalent bonding also occurs in compounds,
as in the network solids SiC (both Group IV
elements), SiO2 (Groups IV and VI,
respectively), and molecular gases (e.g.,
carbon dioxide).

THE METALLIC BOND
The bonds formed between an array of
positively charged metallic cations and a "sea"
of negatively charged free electrons—the latter
being "donated" from the outer shells of the
constituent atoms.
 Metallic bonds are non-directional.
 Occurs for all metallic elements and their
alloys (i.e., Group I, I and III metals, and for
the transition metals) to form close-packed
solids.

THE METALLIC BOND
Metallic Bond: Arises from the electrostatic attraction
between cation cores and an electron cloud. The
electrons are said to be delocalized, because they are not
confined to any cation core, but are “free” to move
between the cation cores.
Hence, the metallic bond is non-directional.
+
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+
THE VAN DER WAALS BOND

Weak, secondary bond formed by the
attraction of fluctuating dipoles between,
for example, atoms of the noble gases and
between molecules. Van der Waals bonds
are non-directional.
THE VAN DER WAALS BOND
THE HYDROGEN BOND

Weak, secondary bond formed by the
attraction of polar molecules. A polar
molecule (or dipole) results from a
permanent imbalance in the electron
distribution in a molecule. This is
between an electronegative atom (e.g.,
oxygen) and an electropositive atom (e.g.,
hydrogen). Hydrogen bonds are
directional.
THE COVALENT BOND AND
WATER


The water molecule consists of one oxygen atom covalently bonded to two
hydrogen atoms.
However, the oxygen atom attracts the shared electron pairs more strongly
than do the hydrogen atoms, and the shared electrons “spend more time”
with the oxygen atom. Hence, a permanent dipole develops with slightly
positive charges on the hydrogen atoms and slightly negative charges on
the oxygen atoms.
THE HYDROGEN BOND AND
THE CRYSTAL STRUCTURE OF
ICE
The monomer of the ice structure consists of a central,
covalently bonded molecule of water, which is
hydrogen bonded to four other water molecules.
 When the monomers are assembled to create the
crystal structure of ice, a hexagonal material results.
