4.6
NAMING IONIC COMPOUNDS
The name of a binary ionic compound is simply the name of the cation (name of the metal atom) followed by the name of the anion (name of nonmetal with ending
changed to -
ide
).
If the metal has the same oxidation state in
all of its compounds, the oxidation state is not
indicated. The metals for which the oxidation
state is usually omitted are the metals of
Groups 1A and 2A, Al, Sc, Zn, Ag, and Cd. Th
e remaining metals have more than one
possible oxidation state, and so the oxidation state of the metal is indicated with a Roman numeral in parentheses after the name of the me
tal. Note that there is no space between the
name of the metal and the Roman numeral in parenthesis. Example 4.9
Name the following binary ionic compounds. AlBr(^3)
Al is aluminum, which is always +3, so the
oxidation state is not required. Br represents
the bromide ion. The nam
e of the compound is
aluminum bromide
.
ZnCl
(^2)
The cation is Zn
2+, but zinc is always +2, so the oxi
dation state is not indicated in the
name. The compound is
zinc chloride
.
Ag
O 2
Silver is always Ag
1+, and the name is simply
silver oxide
.
FeCl
(^2)
Iron is commonly found in the +2 and +3 oxi
dation states. Thus, there is more than one
iron chloride. To distinguish between the two iron chlorides, we indicate that in this compound the iron is in the +2
oxidation state. The name is
iron(II) chloride
.
CuCl Copper is usually found as a +2 ion; but, as
in this compound, it can also form compounds
in the +1 oxidation state. To distinguish this compound from the more common CuCl
, we 2
name it
copper(I) chloride.
PbO
(^2)
Lead forms compounds in both the +2 and +4
oxidation states. Thus, this compound is
named
lead(IV) oxide
.
Hg
Cl 2
(^2)
Cl is -1 (Rule 6), so Hg must be +1. Hg also forms +2 ions, so the compound is mercury(I) chloride
.^
Chapter 4 The Ionic Bond© byNorthCarolinaStateUniversity