Name ___________________________________ Date ______________________ Class ______________________
Chapter 9 – Chemical Names and Formulas
Binary Ionic Compounds
Naming Ions
For metal ion: use the element name with the word “ion” written after it. The word “ion” MUST be included to
distinguish the ion from the element
Examples:
Na+1 sodium ion
Ca+2 calcium ion
Al +3 aluminum ion
For nonmetal ions: the element name is given an –ide ending.
Examples:
C-4 carbide ion
F-1 fluoride ion
-3
-3
N
nitride ion
P
phosphide ion
O-2 oxide ion
Cl-1 chloride ion
Br-1 bromide ion
S-2 sulfide ion
I-1 iodide ion
**Work the following problems – for each of the following, if given the ion symbol, write the correct name; if given the
ion name, and write the correct symbol.
Ion Name
lithium ion
magnesium ion
strontium ion
potassium ion
zinc ion
silver ion
calcium ion
sodium ion
carbon ion
boron ion
Ion Symbol
Ion Symbol
N-3
O-2
F-1
P-3
Cl-1
Br-1
S-2
Au+1
C-4
I-1
Ion Name
Naming Binary Ionic Compounds When Given the Chemical Formula
Binary ionic compounds are composed of two ions, a positive ion (metal ion) and a negative ion (nonmetal ion).
The positive ion is ALWAYS written first in the formula and therefore the compound name BEGINS with the name of the
positive ion. The name of the positive ion is the same as the element name. The negative ion names takes an -ide
ending.
Example: the ion of sodium is the sodium ion, Na+1; the ion of chlorine is the chloride ion, Cl-1.
When naming any ionic compound, the word “ion” is not used. It is understood that ions are involved in ionic
compounds. Thus, the ionic compound NaCl is simply sodium chloride.
The subscripts used in the formulas are not used in the names of ionic compounds. For example, MgCl2 is
named magnesium chloride. It is incorrect to name this compound magnesium chloride “two”. The subscripts are used
in the formulas to balance the numbers of positive and negative charges.
**For naming binary ionic compounds, write the name of the cation first, then write the name of the anion using the
–ide ending. The word “ion” is not used when writing compound names. Also, no reference is made to any numerical
subscripts that may be in the formula.
Examples:
NaCl sodium chloride
LiF lithium fluoride
CaCl2 calcium chloride
BaO barium oxide
Na3N sodium nitride
Na2O sodium oxide
**Work the following problems – Name the following binary ionic compounds.
Formula
KF
BaS
Li2O
ZnCl2
Ba3N2
Compound Name
Formula
CaO
Al2O3
Mg3P2
Na2N
CaBr2
Compound Name
Writing Binary Ionic Formulas When Given the Compound Name
When writing formulas for binary ionic compounds, first write the ions with the correct charges. Then write the
element symbols without the charges, placing the metal first. Now balance the electrical charges. The net charge on
the compound must be zero. (Ask yourself: how many positive charges are needed to balance the negative charges?)
Example 1: sodium chloride
Ions needed: Na+1 and Cl-1
Since each ion has one unit of charge, only one of each ion is needed in the formula, and no subscripts are used.
The formula for sodium chloride is NaCl.
Example 2: sodium oxide
Ions needed: Na+1 and O-2
Sodium ion has one unit of positive charge while the oxide ion has 2 units of negative charge. Therefore, 2 units
of positive charge are required to balance the 2 units of negative charge. A subscript “2” written after the sodium
symbol will indicate that there are 2 sodium ions. The formula for sodium oxide is Na2O.
Example 3: magnesium nitride
Ions needed: Mg2+ and N-3
Each magnesium ion has 2 units of positive charge. Each nitride ion has 3 units of negative charge. To calculate
how many of each ion are needed to have the net charge be zero: use the least common multiple: 2 x 3 = 6.
How many magnesium ions are needed to give a total positive charge of 6+? Each magnesium ion has a charge
of +2; so 6 divided by 2 equals 3. Three magnesium ions are needed.
How many nitride ions are needed to give a total negative charge of 6-? Each nitride ion has a charge of -3; so 6
divided by 3 equals 2. Two nitride ions are needed. The formula for magnesium nitride is Mg3N2.
**For any ionic compound, the total number of positive charges MUST balance the total number of negative charges.
The net charge MUST be zero.
First, write the ion symbol over the name of each ion. (This will help you learn the names and correct formulas for each
of the ions!) Then write the correct formula.
Examples:
Na+1
Cl-1
Sodium chloride
NaCl
Ba+2 F-1
Barium fluoride
BaF2
K+1
O-2
Potassium oxide
K2O
**Work the following problems – Write the correct balanced formulas for each of the following binary ionic compounds.
Compound Name
calcium phosphide
magnesium oxide
barium nitride
aluminum phosphide
silver sulfide
magnesium nitride
sodium carbide
calcium chloride
zinc phosphide
Formula
Compound Name
potassium chloride
lithium fluoride
sodium sulfide
silver chloride
zinc oxide
potassium nitride
barium fluoride
calcium nitride
beryllium bromide
Formula
**Work the following problems – For each of the following, name the compound if the formula is given; write the
correct formula if the name is given.
Formula
NaF
CaCl2
MgO
KCl
KI
BaBr2
Al2S3
Ag2O
Ca3P2
AlF3
Na4C
HF
MgI2
Compound Name
Compound Name
barium sulfide
sodium phosphide
lithium bromide
potassium oxide
calcium oxide
silver phosphide
strontium carbide
calcium iodide
potassium sulfide
magnesium fluoride
lithium sulfide
calcium bromide
aluminum fluoride
Formula