NOMENCLATURE

1
NOMENCLATURE
OF IONIC
COMPOUNDS
2

• Ionic compounds contain positive and negative
  ions. They are held together by electrostatic
  attraction. Most of the negative ions have only
  one possible oxidation state. This is not the
  case with the positive ions. Many of these ions
  have several oxidation states. The use of
  prefixes in naming these compounds could lead to
  confusion. Consequently a new method the stock
  system is very specific in the naming of ionic
  compounds.

3

• Ionic compounds may contain (1) a metal and a
  non-metal, (2) a metal and a polyatomic ion or
  (3) a positive polyatomic ion and a negative
  polyatomic ion. No matter which is used the
  procedure for the stock system is the same. The
  most difficult issue when using the stock
  system is the memorization of polyatomic ions
  and their oxidation states. The most common must
  be committed to memory. Look for trends....
• Note location of metals (lower left) and
  non-metals (upper right) on the periodic chart.
  Metaloids which border the stair-step transition
  line may behave as either positive or negative
  ions.

4

• For example the oxy-salts of chlorine, bromine
  and iodine have many trends in common. Look for
  them below

The next table contains the polyatomic ions that
need to be committed to memory. Remember to
learn the name, formula and oxidation number
5
POLYATOMIC IONS
Ions with -1 charge perbromate BrO4-1 bromate
BrO3-1 bromite BrO2-1 hypobromite
BrO-1 perchlorate ClO4-1 chlorate
ClO3-1 chlorite ClO2-1 hypochlorite
ClO-1 periodate IO4-1 iodate
IO3-1 iodite IO2-1 hypoiodite
IO-1
nitrate NO3-1 nitrite
NO2-1 hydroxide OH-1 cyanide
CN-1 thiocyanate SCN-1 acetate
C2H3O2-1 Permanganate MnO4-1 bicarbonate
HCO3-1 Ions with a -2 Charge carbonate
CO3-2 phthalate C8H4O4-2 sulfate
SO4-2
sulfite SO3-2 chromate
CrO4-2 dichromate Cr2O7-2 oxalate
C2O4-2 peroxide O2-2 Ions with a -3
Charge phosphate PO4-3 phosphite
PO3-3 arsenate AsO4-3 Ions with 1
charge ammonium ion NH41
6
POLYATOMIC IONS
Ions with -1 charge perbromate BrO4-1 bromate
BrO3-1 bromite BrO2-1 hypobromite
BrO-1 perchlorate ClO4-1 chlorate
ClO3-1 chlorite ClO2-1 hypochlorite
ClO-1 periodate IO4-1 iodate
IO3-1 iodite IO2-1 hypoiodite
IO-1
nitrate NO3-1 nitrite NO2-1 hydroxide OH-1 cyanide
CN-1 thiocyanate SCN-1 acetate C2H3O2-1 Permangan
ate MnO4-1 bicarbonate HCO3-1 Ions with a -2
Charge carbonate CO3-2 phthalate C8H4O4-2 sulfate
SO4-2
sulfite SO3-2 chromate
CrO4-2 dichromate Cr2O7-2 oxalate
C2O4-2 peroxide O2-2 Ions with a -3
Charge phosphate PO4-3 phosphite
PO3-3 arsenate AsO4-3 Ions with 1
charge ammonium ion NH41
7
BrO4-1 BrO3-1 BrO2-1 BrO-1 ClO4-1 ClO3-1 ClO2-1 C
lO-1 IO4-1 IO3-1 IO2-1 IO-1
Ions with -1 charge perbromate bromate bromite hyp
obromite perchlorate chlorate chlorite hypochlorit
e periodate iodate iodite hypoiodite
8

• It is also important to memorize the oxidation
  of the monatomic ions that
• have fixed oxidation numbers (positive
• or negative). In particular, those from
  groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A and the
  elements Zn, Cd and Ag. Use the following
  periodic chart to determine their oxidation
  numbers. Just click on the element symbol

9
Elements with Fixed Oxidation Numbers
1
2
3
0
-4
-3
-2
-1
8A
7A
1A
H
H
He
6A
5A
4A
3A
2A
N
B
C
O
F
Ne
Li
Be
Click on element to see its oxidation number(s)
Al
Si
P
S
Cl
Ar
Na
Mg
Sc
Ti
V
Cr
Mn
Fe
K
Ca
Ga
Ge
As
Se
Br
Kr
Co
Ni
Cu
Zn
Y
Zr
Nb
Mo
Tc
Ru
Rb
Sr
In
Sn
Sb
Te
I
Xe
Rh
Pd
Ag
Cd
La
Hf
Ta
Re
Os
Ce
Ba
Tl
Pb
Bi
Po
At
Rn
Ir
Pt
Au
Hg
W
Ac
Rf
Db
Sg
Rh
Hs
Fr
Ra
Mt
Next Slide
10
Naming Ionic Compounds

• The positive ion (usually a metal) is named first
  while the negative ion (a non-metal or a
  polyatomic ion) is named last.
• The charge on the negative ion is used to
  determine the charge on the positive ion. The
  oxidation state of a compound is always zero,
  otherwise it would be a polyatomic ion. In-order
  for the total oxidation state to be zero the
  total positive charge must equal the total
  negative charge. A simple algebraic equation can
  be used to determine the charge on a single metal
  ion. This charge is expressed as a Roman
  Numeral in parenthesis that immediately follows
  the name of the metal.
• If the positive ion is one that has a fixed
  oxidation number then no Roman Numeral is used.
  Everyone should know the charge of that ion.
  These include metals in group 1A, 2A and the
  specific metals Al, Zn, Cd Ag.

11

• If the ionic compound is binary it will end in
  -ide. However, not all compounds that end in
  -ide are binary. For example sodium hydroxide
  has the formulaNaOH (three different kinds of
  atoms).
• If the negative ion is a polyatomic ion the
  compound is no longer binary. The ending will be
  that carried by the polyatomic ion. These
  endings are either -ate or -ite.
• Hydrated compounds are named using a combination
  of both the stock system and prefixes. A prefix
  is used to denote the number of water molecules
  attached to the ionic formula. hydrate is used
  as the name indicating that water is attached.
  For example, copper(II) sulfate pentahydrate has
  the formula CuSO4.5H2O

12
Examples 1- Formulas to Names

• CuSO3

1. Write the names of the ions
0
-2
2. Determine the charge of the positive ion
Cu
SO3
2
x
X (- 2) 0
Im a polyatomic ion
You must know the charge on the sulfite ion is -2
The sum of the positive and negative charges must
equal zero
2 2
X 2
copper
sulfite
(II)
Final Name
Next
13
Examples 2- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
X (-1) 0
Kx (MnO4)-1 0
Im a polyatomic ion

• KMnO4

potassium
permanganate
(I)
If the positive ion has a fixed charge, it is not
shown
Final Name
14
Examples 3- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
X (-1) 0
NH4x (NO3)-1 0
Im a polyatomic ion

• NH4NO3

ammonium
nitrate
(I)
Final Name
If the positive ion has a fixed charge, it is not
shown
15
Examples 4- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 2
X 2(-1) 0
Snx (F-1)2 0
Im not a polyatomic ion

• SnF2

tin
fluoride
(II)
Final Name
16
Examples 5- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 2
X 2(-1) 0
Bax (ClO4-1)2 0
Im a polyatomic ion

• Ba(ClO4)2

barium
perchlorate
(II)
If the positive ion has a fixed charge, it is not
shown
Final Name
17
Examples 6- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
2X (-2) 0
2Cux (S)-2 0
Im not a polyatomic ion

• Cu2S

copper
sulfide
(I)
Final Name
18
Examples 6- Formulas to Names

• Cu2S

1. Write the names of the ions
-2
2. Determine the charge of the positive ion
(Cu )2
S
1
x
2X (- 2) 0
The sum of the positive and negative charges must
equal zero
You must know the charge on the sulfide ion is -2
2 2
2X 2
X 1
copper
sulfide
(I)
Final Name
Next
19
Examples 7- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
2X (-2) 0
2(Nax)(Cr2O7)-2 0
Im a polyatomic ion

• Na2Cr2O7

sodium
dichromate
(I)
If the positive ion has a fixed charge, it is not
shown
Final Name
20
Examples 8- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
2X (-2) 0
2(Nax) (O2-2) 0
Im a polyatomic ion

• Na2O2

peroxide
sodium
(I)
If the positive ion has a fixed charge, it is not
shown
Final Name
21
Examples 9- Formulas to Names
1. Write the names of the ions
Im a hydrated compound, this part will be named
last
2. Determine the charge of the positive ion
X 3
X (-3) 0
Fex (PO3 -3) 0
Im a polyatomic ion

• FePO3 .3H2O

.3H2O
3
iron
phosphite
tri
hydrate
(III)
Final Name
22
Examples 10- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the positive ion
X 1
X (-1) 0
Lix (CN-1) 0
Im a polyatomic ion

• LiCN

lithium
cyanide
(I)
If the positive ion has a fixed charge, it is not
shown
Final Name
23
Writing Ionic Formulas

• It is easier to write the formula of an ionic
  compound from its name than the reverse. The
  oxidation state (or charge) of all compounds is
  zero. This is the first naming system that
  requires the balancing of the positive and
  negative charges such that the result is zero.
• The oxidation number of the negative ion must be
  memorized in all cases. Refer to the table of
  polyatomic ions.

24

• The positive ion is either one of those that has
  a fixed oxidation number or a Roman Numeral
  will follow the positive ion. Metals that have
  only one oxidation number must be memorized.
  These include metals in group 1A, 2A and the
  specific metals Al, Zn, Cd Ag. If there is a
  Roman Numeral is in the name, it represents the
  charge of one of the positive ions.

25

• Remember the total positive charge must equal to
  the total negative charge. The result is a
  compound which has no charge. Multiply the
  oxidation numbers of both the positive and
  negative ions by a number that will result in the
  smallest identical numbers of positive and
  negative charges. These multipliers represent
  the number of atoms of each ion required to give
  a neutral ionic compound.

26

• The formulas of hydrated compounds are written
  using a combination of both the stock system and
  prefixes. A prefix is used to denote the number
  of water molecules attached to the ionic formula.
  hydrate is used as the name indicating that
  water is attached. For example, copper(II)
  sulfate pentahydrate has the formula CuSO4.5H2O
  (notice a dot separates the ionic compound from
  the water of hydration)

27
Example 1-Names to Formulas
1. Write symbols of elements
3X 1y
X(3) y(-1) 0
2. Determine number of ions
(Al )x(Cl-1)y 0
3
What is the Lowest Common Multiple LCM of 3 and
1. Do not worry about the sign(/-)

• aluminum chloride

If there is no Roman Numeral, you need to know
the fixed oxidation number of the positive ion.

If there is no Roman Numeral, you need to know
the fixed oxidation number of the positive ion.

Choose the lowest set of integers thatsatisfies
the equation
Cl
Al
3
1
Final Formula
If there is only one atom the 1 is not shown
Next
28
Example 1-Names to Formulas

• aluminum chloride

1. Write symbols of elements
2. Determine number of ions
(Al )x(Cl-1)y
3
If there is no Roman Numeral, you must know the
oxidation number of the positive ion.
If there is no Roman Numeral, you must know the
oxidation number of the positive ion.
For aluminum, a 1 is multiplied times the 3 to
give a 3 charge
What is the Lowest Common Multiple LCM of 3 and
1. Do not worry about the sign(/-)
What is the Lowest Common Multiple LCM of 3 and
1. Do not worry about the sign(/-)
X(3) y(-1) 0
Remember all compounds are neutral, thus the
total positive charge must equal the total
negative charge
This formula says that the 3 charge of one
Al atom will cancel the-3 charge from 3 Cl atoms
For chloride, a 3 is multiplied times the -1 to
give a -3 charge
1(3) 3(-1) 0
Cl
Al
3
1
If there is only one atom the 1 is not shown
Final Formula
Next
29
Example 2-Names to Formulas
1. Write symbols of elements
2X 1y
X(2) y(-1) 0
2. Determine number of ions
(Co2)x(BrO3-1)y 0

• cobalt(II) bromate

Choose the lowest set of integers thatsatisfies
the equation
BrO3
(BrO3)2
Co
1
If there is only one atom the 1 is not shown
Final Formula
Next
30
Example 3-Names to Formulas
1. Write symbols of elements
3X 1y
X(3) y(-1) 0
2. Determine number of ions
(Ni3)x(C2H3O2-1)y 0

• nickel(III) acetate

Choose the lowest set of integers thatsatisfies
the equation
(C2H3O2)3
C2H3O2
Ni
1
Final Formula
If there is only one atom the 1 is not shown
Next
31
Example 4-Names to Formulas
1. Write symbols of elements
1X 3y
X(1) y(-3) 0
2. Determine number of ions
(Li )x(PO4-3)y 0
1

• lithium phosphate

Choose the lowest set of integers thatsatisfies
the equation
If there is no Roman Numeral, you need to know
the fixed oxidation number of the positive ion.

If there is no Roman Numeral, you need to know
the fixed oxidation number of the positive ion.

PO4
(PO4)1
Li
3
Final Formula
If there is only one atom the 1 is not shown
Next
32
Practice Problems

• By now you should have an idea of what is
  expected when naming covalent binary compounds
  using prefixes.
• In order to master this naming system you need
  to practice until you feel proficient in naming
  compounds using prefixes.

33
Practice Problem 1

• Fe(NO3)3

Choose the correct name for the compound
1. Iron trinitrate
No, you do not use prefixes
2. iron(I) nitrate
No, you have the wrong oxidation number
3. iron(III) nitrite
No, you need to review polyatomic ions
4. iron(III) nitrate
Very good, click arrow to continue
5. none of the above
No, there is a correct answer
next problem
Polyatomic Ions
Periodic Chart
34
Practice Problem 2

• sodium chlorite

Choose the correct formula for the compound
1. NaCl
No, you need to review prefixes
2. NaClO
No, you need to review prefixes
3. NaClO2
Very good, click arrow to continue
No, you have several errors
4. Na(ClO)2
No, there is a correct answer
5. none of the above
next problem
Prefixes
Periodic Chart
35
POLYATOMIC IONS
Ions with -1 charge perbromate BrO4-1 bromate
BrO3-1 bromite BrO2-1 hypobromite
BrO-1 perchlorate ClO4-1 chlorate
ClO3-1 chlorite ClO2-1 hypochlorite
ClO-1 periodate IO4-1 iodate
IO3-1 iodite IO2-1 hypoiodite
IO-1
nitrate NO3-1 nitrite
NO2-1 hydroxide OH-1 cyanide
CN-1 thiocyanate SCN-1 acetate
C2H3O2-1 Permanganate MnO4-1 bicarbonate
HCO3-1 Ions with a -2 Charge carbonate
CO3-2 phthalate C8H4O4-2 sulfate
SO4-2
sulfite SO3-2 chromate
CrO4-2 dichromate Cr2O7-2 oxalate
C2O4-2 peroxide O2-2 Ions with a -3
Charge phosphate PO4-3 phosphite
PO3-3 arsenate AsO4-3 Ions with 1
charge ammonium ion NH41
return
36
Oxidation Numbers (most common)
1
2
3
0
-4
-3
-2
-1
1A
8A
7A
H
H
He
6A
5A
4A
3A
2A
N
B
C
O
F
Ne
Li
Be
Click on element to see its oxidation number(s)
Al
Si
P
S
Cl
Ar
Na
Mg
Sc
Ti
V
Cr
Mn
Fe
K
Ca
Ga
Ge
As
Se
Br
Kr
Co
Ni
Cu
Zn
Y
Zr
Nb
Mo
Tc
Ru
Rb
Sr
In
Sn
Sb
Te
I
Xe
Rh
Pd
Ag
Cd
La
Hf
Ta
Re
Os
Ce
Ba
Tl
Pb
Bi
Po
At
Rn
Ir
Pt
Au
Hg
W
Ac
Rf
Db
Sg
Rh
Hs
Fr
Ra
Mt
Nd
Pm
Sm
Eu
Gd
Tb
Ce
Pr
Yb
Lu
Dy
Ho
Er
Tm
return
Np
Am
Cm
Bk
Th
Pa
No
Lr
Cf
Es
Fm
Md
U
Pu