9-1 NAMING IONS
MAIN IDEAS
IaN
1. MONOATOMIC PG.
ION
3
2. POLYATOMIC
ION
Objective
Identify charges of
monoatomic ions.
Define polyatomic
ions & write the
names & formulas.
Identify the 2
common endings for
the the names of
most polyatomic
ions.
Key Concepts: x3 (See page 253)
CHAPTER 9
Chemical Names
and Formulas
REVIEW: IONIC COMPOUNDS
 Ionic
compounds formed from monoatomic
ions…


Nonmetals combining with metals
Attraction is from opposite charges (cations &
anions)
Cations come from groups 1, 2 & 3
 Anions come from groups 5, 6, & 7


Net charge of the compound is always zero
(neutral)
 To

name the cations…
Just use the name of the metal and the word
“ion” or “cation”

Examples:
Na+ = sodium ion or sodium cation
+ = potassium ion or potassium cation
K
2+ = magnesium ion or magnesium cation
 Mg

 To
determine the charge of a nonmetal,
we looked at the valence electrons
(which was the same as the group
number) and then decided how many
electrons the atom wanted to gain to be
like a noble gas.

Ex. Oxygen in group 6, has 6 valence
electrons – so it wants to gain 2 more
electrons to have a full octet. That gives it a
net charge of 2-
 Another
method is to just subtract the
group number from 8 to decide on the
net charge.
 Ex.
5A
6A
7A
N
O
F
P
S
Cl
Se
Br
2-
1-
3-
NAMING ANIONS
Add
the suffix –ide to the
element name.
 Ex.
Fluoride
Bromide
Chloride
Iodide
Nitride
Selenide
Sulfide

IONS OF TRANSITION
METALS
Transition
metals are in
groups 1-8B (It’s the B’s!)
 Many
of the transition
metals form more than 1
cation with different ionic
charges.
Ex. Fe2+ and Fe3+
Ex. Pb2+ and Pb3+

NAMING IONS OF TRANSITION METALS
 Two
different naming systems are used:
1. The Stock System (preferred)
 A Roman numeral is placed in parentheses
after the name of the element to indicate the
value of the charge.
2+ = iron(II) ion
 Ex. Fe
Fe3+ = iron(III) ion
 2. The Classical System
 This system uses different suffixes to
differentiate…
 -ous is tacked on to the smaller charge
 -ic is tacked on to the larger charge


Ex. Fe2+ = ferrous ion
Fe3+ = ferric ion
**Note that the original root name of the
element is being used (ferrum = iron)
BACK TO THE ROOTS…
An Example
Root Name
of Element
Element as
we Know it
Stannous ion
Stannum
(Latin)
Tin
Ferrous ion
Ferrum
(Latin)
Iron
Plumbous ion
Plumbum
(Latin)
Lead
MISC…
A
disadvantage of the classical
naming system is that you
cannot tell the actual charge of
the ion by the name. (this is
what makes the stock system
better)
 Some transition metals only
form 1 type of ion and do not
use a Roman numeral.