Chemistry 101 H
Chemical Bonding
Chapter 3 - Chemical Bonding
This presentation was created by
Professor Carl H. Snyder
Chemistry Department
University of Miami
Coral Gables, FL 33124
CSnyder@miami.edu
Copyright 2004 by Carl H. Snyder,
University of Miami. All rights
reserved.
A Chemical Reaction
An Ordinary Product From
Extraordinary Reactants
Sodium, a
dangerous,
metallic solid,
and
. . . to form sodium
choride, common
table salt.
chlorine, a
poisonous,
yellow gas,
react with
each other . .
Lewis Structures
Atomic Weight
An element’s atomic weight, atomic
mass, average atomic weight, and
average atomic mass all refer to the
same value:
Valence electrons occupy the valence shell,
the outermost shell of electrons.
The Lewis structure shows only the atomic
symbol and the valence electrons.
the average of the masses of all of its
isotopes, weighted for the
abundance of each.
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The Periodic Table
(A Modern Version)
Families and Periods
Atomic Number, Atomic
Weight
The whole number
above (in this case) or
below the elemental
symbol represents the
atomic number
The fractional number
above or below (in this
case) the symbol
represents the atomic
weight or the atomic
mass
The Alkali Metal Family
The alkali metals
Except for hydrogen,
each is a metal that
reacts with water to
produce hydrogen
gas.
Each has a single
valence electron.
The Alkaline Earth
Family
The alkaline earth
family.
Each is a metal.
Each has two valence
electrons.
The Halogen Family
The Halogen Family
Each member reacts with
an alkali metal to form an
electrolyte
Each member lacks only a
single valence electron to
form a complete (or
temporarily complete)
valence shell.
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The Noble or Inert
Gas Family
The Noble or Inert Gas
Family
All of the elements in
this family are inert, or
nearly inert gases.
Each holds a filled (or
temporarily filled)
valence shell.
Na + Cl ---> NaCl
Lewis Structures
Here, the transfer of an electron from the
sodium atom to the chlorine atom is shown
through Lewis structures.
Ionic Bonds
Na + Cl --> NaCl
Full Electronic Structures
An electron transfers from the valence shell of
the sodium atom to the valence shell of the
chlorine atom, creating a sodium cation and a
chloride anion.
The Sodium Chloride Crystal
In a crystal of sodium
chloride, the sodium
cations and chloride
anions arrange
themselves next to
each other, in an
orderly, 3-dimensional
array.
They are held in
position by ionic
bonds.
The Reaction of Calcium and
Chlorine
An ionic bond results from the mutual
attraction of oppositely charged ions.
An ionic bond forms as a result of the
mutual attraction of a
cation (such as a sodium ion) and an
anion (such as a chloride ion).
One calcium atom, with two valence electrons, reacts
with two chlorine atoms, each of which requires only one
electron to complete its octet.
The product consists of one calcium cation and two
choride anions, CaCl2, calcium chloride.
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A Covalent Bond
The Covalent Bond -- H2
A covalent bond forms as two atoms
share a pair of electrons.
A shared pair of electrons characterizes a
covalent bond.
The Covalent Bond -- F2
Diatomic Molecules with
Single Bonds
Hydrogen
H-H
H2
The Halogens
F-F
F2
Cl-Cl Cl2
Br-Br Br2
I-I
I2
Oxygen - A Diatomic Molecule
with a Double Bond
Nitrogen - A Diatomic
Molecule With A Triple Bond
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Water, A Covalent Compound
A water molecule, H2O, forms as two H atoms
share their valence electrons with an O atom.
Ionization
Ionization occurs when
a covalent bond
ruptures to form a
cation and an anion.
Water ionizes when a
proton (a hydrogen
nucleus) moves away
from the pair of
electrons it shares with
another atom.
The Reversible Ionization of
Water
Reversible ionization
takes place when both
ionization and the
recombination of the
ions occur concurrently
throughout the
substance.
It’s indicated by two
arrows, with reversed
directions.
End - Chapter 3
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