Chemistry 11
Resource: Chang’s Chemistry Chapter 9
Activities
Quizzes
 Exercises
 Molecular geometry models
 Lab: Comparing ionic and covalent
compounds
 Lab: Boiling points

Objectives







Describe the ionic bond as the electrostatic
attraction between oppositely charged ions.
Describe how ions can be formed as a result of
electron transfer.
Deduce which ions will be formed by elements in
groups 1, 2, 3, 5, 6, and 7.
State that transition elements can form more than
one ion.
Predict whether a compound of two elements would
be ionic from the position of the elements in the
periodic table or from their electronegativity values.
State the formula of common polyatomic ions
formed by nonmetals in periods 2 and 3.
Describe the lattice structure of ionic compounds.
Lewis dot symbols
The discovery of the periodic table and
electron configuration gave rise to an even
greater understanding of chemistry—
bonding.
 Lewis stated that:

 Atoms combine to achieve greater stability
 Maximum stability is achieved when the electron
configuration resembles that of a noble gas.

What properties of noble gases support
this?
Lewis dot symbols
A Lewis dot symbol is a representation of
an element.
 It consists of:

 The symbol of the element
 One dot for every valence electron in an atom of
the element.

What other representations of elements
have we used so far?
Lewis dot symbols
Lewis dot symbol of
Lewis dot symbols
Draw the Lewis dot symbol for:
 hydrogen
 sodium
What do you notice?
Draw the Lewis dot symbol for:
 carbon
 oxygen
Ion formation
Recall the definition of an ion and the two
types of ions.
 Why do atoms form ions?
 What roles do you think ionization energy
and electronegativity play in the formation
of ions?

Factor
High ionization energy
High electronegativity
Cation or Anion?
Ion formation

Explain why atoms form ions using
Lewis’s ideas.
Factors that affect the formation of ions
Factor
high ionization energy
Cation or Anion?
anion
low ionization energy
high electronegativity
low electronegativity
cation
anion
cation
Ion formation
Predict and explain the ion formation of the
following elements:
 lithium
 sodium
 beryllium
 magnesium
 aluminum
 oxygen
 fluorine
Ion formation

As a rule:
 the alkali metals (Group I) and alkaline
earth metals (Group II) form cations, and
 the halogens and oxygen form anions

With this in mind, how do you think ionic
bonds are formed?
The ionic bond
An ionic bond is the electrostatic force
that holds ions together in an ionic
compound.
 Consider the compound lithium fluoride.

 Macroscopically, it is a poisonous white
powder used in manufacturing.
 Use your knowledge of electron
configuration to describe lithium fluoride at
the atomic / molecular level.
The ionic bond
The electron configurations of lithium and
fluoride are:
Li 1s22s1
F 1s22s22p5
Lithium surrenders its 2s1 valence
electron to fluorine and thus, both
achieve the electron configuration of a
noble gas.
The ionic bond
Write the electron configurations of Li and F
when they are in an ionic compound.
Which noble gases’ configurations do they
resemble?
The process can also be represented using
Lewis dot symbols (p 247)
Notice the steps involved in the formation
of the ionic bond between Li and F.
Ionic compounds
What holds ionic compounds together?
 The ions involved in ionic compounds
are electrically charged. Can we then
assume that ionic compounds are also
charged?

Ionic compounds
Ionic compounds are held together by
the electrostatic force between charged
ions, but
 Ionic compounds themselves are
electrically neutral.

Lattice structure

Consider a very common ionic
compound, NaCl (rock salt). What is its
gross appearance?
The transition metals
The transition metals are known to
commonly form more than one ion.
 This comes from the existence of the 3d
subshell.
 Ions of transition metals are commonly
of the +2 and +3 charges.
 Which subshell are the electrons of
transition metals taken from?

Polyatomic ions
It is not uncommon for two nonmetals to
join to form a polyatomic ion.
 Can you predict the charge of the
following polyatomic ions?

 hydroxide (OH)
 ammonium (NH4)
Polyatomic ions

One of the elements will be considered as
“positive” and the other will be considered
“negative”.
Some common polyatomic ions
Name
Molecular formula
hydroxide
OH
nitrate
NO3
sulfate
SO3
cyanide
CN
carbonate
CO3
ammonium
NH4
Charge
Objectives







Describe the ionic bond as the electrostatic
attraction between oppositely charged ions.
Describe how ions can be formed as a result of
electron transfer.
Deduce which ions will be formed by elements in
groups 1, 2, 3, 5, 6, and 7.
State that transition elements can form more than
one ion.
Predict whether a compound of two elements would
be ionic from the position of the elements in the
periodic table or from their electronegativity values.
State the formula of common polyatomic ions
formed by nonmetals in periods 2 and 3.
Describe the lattice structure of ionic compounds.
Exercises
Chang’s Chemistry
p 378