Topic
Name
Date
How can we understand, describe,
and name chemical compounds?
2.2
Summary
Textbook pages 118 to 139
Before You Read
List the names or chemical formulas of compounds you know already.
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
Chemical compounds are represented using chemical names and
chemical formulas.
To tell different compounds apart, each one is given a unique chemical name. Each
chemical name can be translated into a chemical formula. A chemical formula is a group
of letters and subscript numbers that represent the make-up of a chemical compound. The
letters in the compound are the chemical symbols of the elements in the compound. The
subscript numbers tell you how many atoms of these elements are in the compound.
Reactive elements can become more stable when they form
compounds.
When elements form compounds, they become more stable because when the elements
combine to form compounds, each element makes a full outer electron shell.
• Metal elements lose electrons to form positive ions to become more stable.
• Non-metal elements can gain electrons to form negative ions OR non-metals can share
electrons to become more stable.
Ions are atoms that have either a positive electrical charge or a negative
electrical charge.
44 MHR • Unit 2 Chemical Reactions and Their Practical Applications 978-0-07-031869-4
Topic
Name
2.2
Date
Summary
Chemical compounds are described as either ionic or
molecular.
Ionic compound
Molecular compound
An ionic compound forms
when a positively charged metal
ion attracts a negatively charged
non-metal ion. Ionic compounds
are solids at room temperature,
have very high melting points,
and conduct electricity when
they are melted or dissolved in
water.
A molecular compound forms
when non-metal atoms share
electrons. Molecular compounds
may be solids, liquids, or gases
at room temperature; have lower
melting points than ionic
compounds; and do not conduct
electricity when melted or
dissolved in water, except in the
case of certain acids.
1. What do the letters
in a chemical
formula represent?
______________
______________
2. What is an ion?
______________
Ionic compounds are named with the metal ion first,
followed by the non-metal ion ending in”ide.”
Formula-to-name steps
______________
______________
3. What types of
elements combine
to form ionic
compounds and
molecular
compounds?
______________
Name-to-formula steps
______________
______________
______________
4. Write the name or
formula for each
ionic compound.
a) LiCl
_____________
b) sodium oxide
_____________
Topic 2.2 • MHR 45
Topic
Name
Date
Molecular compounds
are named using
numerical prefixes.
Formula-to-name steps
Numerical Number it
prefix
represents
mono-
1
di-
2
tri-
3
tetra-
4
penta-
5
hexa-
6
hepta-
7
octa-
8
5. Write the name or
Name-to-formula steps
formula for each
compound.
a) CO
____________
b) nitrogen
trifluoride
____________
46 MHR • Unit 2 Chemical Reactions and Their Practical Applications 978-0-07-031869-4
2.2
Summary
Topic
Name
Date
How to name a chemical compound
2.2
Summary
Topic 2.2 • MHR 47
Topic
Name
Date
How to write a chemical formula
48 MHR • Unit 2 Chemical Reactions and Their Practical Applications 978-0-07-031869-4
2.2
Summary
Name
Analyze the
Information
Topic 2.2
Date
Use with textbook pages 128 to 135.
Writing names and formulas of ionic
compounds
Use the periodic table on page 148 to help you answer these questions.
1. Use the chart on page 128 of your textbook to help you write the names of these ionic
compounds.
Check page 129 of your textbook for the spelling of each “ide” name.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Chemical formula
Ag2O
KI
LiCl
BaO
ZnF2
Mg3P2
CaBr2
Na2S
AlCl3
Be3N2
Chemical name
2. Use the chart on page 129 of your textbook to help you write the chemical formulas for
these ionic compounds.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Chemical name
beryllium sulfide
lithium nitride
zinc chloride
sodium bromide
calcium chloride
magnesium oxide
silver iodide
aluminum sulfide
potassium fluoride
calcium phosphide
Chemical formula
3. Complete the table. First, identify each ion and its charge. Then, give the formula and name
for each ionic compound formed. The table has been partially completed to help you.
Chlorine becomes
chloride. Cl–1
a)
sodium Na+1
b)
magnesium ____
c)
calcium _____
Fluorine becomes
____________. _____
Oxygen becomes
___________. _____
Topic 2.2 • MHR 49
Name
Date
Use with textbook pages 128 to 135.
Applying
Knowledge
Topic 2.2
Writing names and formulas of
molecular compounds
1. Use the chart on page 131 of your textbook to help you write the names of these
molecular compounds.
Chemical formula
a)
P2O5
b)
CS2
c)
N2O4
d)
SF2
e)
CBr4
f)
BCl3
g)
P2O3
h)
NF3
i)
OF2
j)
SO3
Chemical name
2. Use the chart on page 132 of your textbook to help you write the chemical formulas for
these molecular compounds.
Chemical name
a)
carbon tetrachloride
b)
dinitrogen trioxide
c)
sulfur dichloride
d)
carbon dioxide
e)
dinitrogen monoxide
f)
phosphorus trichloride
g)
nitrogen triiodide
h)
silicon tetrafluoride
i)
hydrogen monobromide
j)
carbon monoxide
Chemical formula
50 MHR • Unit 2 Chemical Reactions and Their Practical Applications 978-0-07-031869-4
Name
Applying
Knowledge
Topic 2.2
Date
Use with textbook pages 128 to 135.
Ionic or molecular?
1. Identify the types of atoms in each compound as either metal or non-metal. Then
decide if the compound is ionic or molecular. Use the periodic table on page 148 to
help you.
Chemical formula
a)
b)
c)
d)
e)
Metal or non-metal
elements?
Ionic or molecular compound?
SrCl2
P2O3
SCl2
CBr4
Rb2S
2. Identify the following compounds as ionic or molecular. Then write the names of the
compounds.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Chemical formula
CO
BaCl2
SF6
BrCl
NaF
MgO
PF5
N2O3
AgCl
Li2Se
Ionic or molecular?
Compound name
3. Identify the following compounds as ionic or molecular. Then write their chemical
formulas.
Compound
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Ionic or molecular?
Compound formula
carbon dioxide
zinc oxide
potassium bromide
dinitrogen pentoxide
aluminum sulfide
phosphorus trichloride
disulfur dinitride
magnesium phosphide
lithium iodide
diphosphorus hexoxide
Topic 2.2 • MHR 51
Name
Use with textbook pages 118 to 139.
How can we
understand, describe,
and name chemical
compounds?
Match each Term on the left with the best
Descriptor on the right. Each term is used
only once.
Term
Descriptor
1. _____ ionic
2. _____ molecular
3. _____ subscript
4. _____ symbol
5. _____ chemical
formula
A. the type of
compound formed
when a metal and
a non-metal
combine.
B. represents the
number of atoms
of each element in
the compound.
C. the type of
compound formed
when two nonmetals combine.
D. short form for a
chemical name of
a compound.
E. the letters in the
chemical formula.
6. Write the name and symbol for a nonmetal element.
__________________________________
7. Check () which compounds are ionic
or molecular.
a)
b)
c)
d)
Assessment
Topic 2.2
Date
Chemical
compound
NaCl
nitrogen
triiodide
potassium
oxide
CO2
Ionic
Molecular
8. Write the chemical
name for each
compound.
Chemical
compound
a)
MgBr2
b)
Al2O3
c)
SI3
d)
P2O3
e)
SiF4
Chemical name
9. Write the chemical formula for each
compound.
Chemical
compound
a)
sodium fluoride
b)
calcium nitride
c)
diphosphorus
trioxide
d)
boron triiodide
e)
beryllium
chloride
Chemical
formula
10. Explain the steps in determining the
chemical formula of a compound from
its name. Use sodium sulfide to help
you explain.
Step 1. _________________________
_______________________________
Step 2. _________________________
_______________________________
Step 3. _________________________
_______________________________
Step 4. _________________________
_______________________________
52 MHR • Unit 2 Chemical Reactions and Their Practical Applications 978-0-07-031869-4