writing ionic compounds

1. 1
Aim: How do we write the
chemical formula of an
ionic compound given
the chemical name

2. Binary Compound
 Binary Compounds are composed of two elements bonded together
 One METAL Ion and One NONMETAL Ion for Ionic Compound
 Metal atoms lose electrons to form positively charged ions. Some metals
form one ion, while others (usually transition metals) can form multiple ions.
 Nonmetal atoms gain electrons to form negatively charged ions.
Nonmetals form only one negative ion.
 General naming format for binary ionic compounds
“metal ion name + nonmetal ion name”

3. 3
Naming Ionic compounds with metals
that have only one oxidation state

4. 4
Names of Some Common Ions
Naming metal ions with one
oxidation state:
Element name + ion
Naming nonmetal ions:
element stem name + “ide” + ion

5. 5
Formula Ions Name
cation anion
NaCl Na+
Cl-
sodium chloride
K2S K+
S2-
potassium sulfide
MgO Mg2+
O2-
magnesium oxide
CaI2 Ca2+
I-
calcium iodide
Al2O3 Al3+
O2-
aluminum oxide
Examples of Ionic Compounds with
Two Elements

6. 6
Learning Check
Chemical
Formula
Positive Ion
(metal ion)
Negative Ion
(nonmetal
ion)
Does the
metal form
one ion?
Mathematic-
ally check if
compound is
neutral
Chemical
Name
CaO
KBr
Al2O3
MgCl2

7. 7
Transition Metals form Positive Ions
Most transition metals and Group 4(14)
metals form 2 or more positive ions.
Zn2+
, Ag+
, and Cd2+
form only one ion.

8. 8
Metals that form more than One Cation
The name of metals with two or more positive ions
(cations) use a Roman numeral to identify ionic
charge.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Lead Pb2+
lead(II)
Pb4+
lead(IV)

9. 9
Naming Variable Charge Metals
Transition metals
with two or more
different ions use
a Roman
numeral after the
name of the
metal to indicate
ionic charge.

10. 10
Naming Ionic Compounds with Variable Charge Metals

11. 11
Naming FeCl2
To name FeCl2
1. Determine the charge of the cation using the charge
of the anion (Cl-
).
Fe ion + 2 Cl-
= Fe ion + 2 (-1) = 0
Fe ion = 2+
2. Name the cation by the element name and add a
Roman numeral in parenthesis to show its charge.
Fe2+
= iron(II)
3. Write the anion with an ide ending.
FeCl2 = iron(II) chloride

12. 12
Naming Cr2O3
To name Cr2O3
1. Determine the charge of cation from the anion (O2-
).
2 Cr ions + 3 O2-
= 0
2 Cr ions + 3(2-) = 0
2 Cr ions - 6 = 0
2 Cr ions = +6
Cr ion = 3+ = Cr3+
2. Name the cation by the element name and add a
Roman numeral in parenthesis to show its charge.
Cr3+
= chromium(III)
3. Write the anion with an ide ending.
chromium(III) oxide = Cr2O3

13. 13
Learning Check
Chemical
Formula
Positive Ion
(metal ion)
Negative Ion
(nonmetal
ion)
Does the
metal form
one ion?
Mathematic-
ally check if
compound is
neutral
Chemical
Name
MgCl2
KCl
AgF
FeO
PbI4

14. 14
1. Determine if the metal is a transition metal.
2. If Transition Metal, Determine the proper oxidation
number to use. (Use nonmetal to help you determine)
3. Write down the name of the metal. (use roman
numerals to show oxidation state for transition metals)
4. Write the name of the non-metal, changing the
ending to ide
Ex: Oxide, Fluoride, Bromide, Chloride, Nitride
Summary Steps to naming Binary Ionic
Compounds