Transcript Slide 1

• 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.
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 nonmetals (upper right) on the periodic chart.
Metaloids which border the stair-step transition
line may behave as either positive or negative
ions.
For example the oxy-salts of chlorine,
bromine and iodine have many trends in
common. Look for them below……
perchlorate ClO4-1
chlorate
ClO3-1
chlorite
ClO2-1
hypochlorite ClO-1
perbromate
bromate
bromite
hypobromite
BrO4-1
BrO3-1
BrO2-1
BrO-1
periodate
iodate
iodite
hypoiodite
IO4-1
IO3-1
IO2-1
IO-1
The next table contains the polyatomic
ions that need to be committed to
memory. Remember to learn the name,
formula and oxidation number
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
chromate
dichromate
oxalate
peroxide
SO3-2
CrO4-2
Cr2O7-2
C2O4-2
O2-2
Ions with a -3 Charge
phosphate
PO4-3
phosphite
PO3-3
arsenate
AsO4-3
Ions with +1 charge
ammonium ion NH4+1
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
nitrite
hydroxide
cyanide
thiocyanate
acetate
Permanganate
bicarbonate
NO3-1
NO2-1
OH-1
CN-1
SCN-1
C2H3O2-1
MnO4-1
HCO3-1
Ions with a -2 Charge
carbonate
CO3-2
phthalate
C8H4O4-2
sulfate
SO4-2
sulfite
chromate
dichromate
oxalate
peroxide
SO3-2
CrO4-2
Cr2O7-2
C2O4-2
O2-2
Ions with a -3 Charge
phosphate
PO4-3
phosphite
PO3-3
arsenate
AsO4-3
Ions with +1 charge
ammonium ion NH4+1
Ions with -1 charge
perbromate
bromate
bromite
hypobromite
perchlorate
chlorate
chlorite
hypochlorite
periodate
iodate
iodite
hypoiodite
BrO4-1
BrO3-1
BrO2-1
BrO-1
ClO4-1
ClO3-1
ClO2-1
ClO-1
IO4-1
IO3-1
IO2-1
IO-1
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…
Elements with Fixed Oxidation Numbers
-1
-2
-3
-4
+3
+2
+1
0
7A 8A
1A
H
2A
Li
Be
3A 4A 5A 6A
Click on element to see its
oxidation number(s)
Na Mg
K
Ca Sc Ti
Rb Sr
Y
V
H
He
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Ce Ba La Hf Ta W Re Os Ir
Pt Au Hg Tl
Pb
Bi
I
Xe
Po At Rn
Fr Ra Ac Rf Db Sg Rh Hs Mt
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa
U
Np Pu Am Cm Bk Cf Es Fm Md No Lr
Next Slide
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.
• 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
formula…NaOH (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
Examples #1- Formulas to Names
1. Write the names of the ions
CuSO3
x
+2
2. Determine the charge of
the positive ion
Cu
The
the positive
You sum
mustofknow
the
and
negative
charges
charge
on the
sulfite
must
ion isequal
-2 zero
-2 = 0
SO3
X + (- 2)I’m
= 0a
+2
+2
polyatomic
X =
+2
ion
copper (II) sulfite
Final Name
Next
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
KMnO4
I’m a
polyatomic
ion
potassium(I) permanganate
If the positive
has a fixed
Finalion
Name
charge, it is not shown
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
NH4NO3
ammonium(I) nitrate
Finalion
Name
If the positive
has a fixed
charge, it is not shown
I’m a
polyatomic
ion
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
SnF2
I’m not a
polyatomic
ion
tin (II) fluoride
Final Name
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
Ba(ClO4)2
I’m a
polyatomic
ion
barium(II) perchlorate
If the positive
has a fixed
Finalion
Name
charge, it is not shown
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
Cu2S
I’m not a
polyatomic
ion
copper (I) sulfide
Final Name
Examples #6- Formulas to Names
1.Write the names of the ions
Cu2S
(Cu+1x )2 S -2
2. Determine the charge of
the positive ion
The
the the
positive
You sum
mustofknow
and
negative
charges
charge
on the
sulfide
must
ion isequal
-2 zero
2X + (- 2) = 0
+2 +2
2X = +2
2
2
X = +1
copper (I) sulfide
Final Name
Next
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
Na2Cr2O7
I’m a
polyatomic
ion
sodium(I) dichromate
If the positive
has a fixed
Finalion
Name
charge, it is not shown
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
Na2O2
I’m a
polyatomic
ion
sodium(I) peroxide
If the positive
has a fixed
Finalion
Name
charge, it is not shown
Examples #9- Formulas to Names
1. Write the names of the ions
2. Determine the charge of
the positive ion
I’m a hydrated
compound,
X = +3this part
will be named last
X + (-3) = 0
Fex (PO3 -3) = 0
FePO3..3H
O
33H22O
I’m a
polyatomic
ion
iron (III) phosphite tri hydrate
Final Name
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
LiCN
I’m a
polyatomic
ion
lithium(I) cyanide
If the positive
has a fixed
FinalionName
charge, it is not shown
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.
• 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.
• 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.
• 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)
Example #1-Names to Formulas
X 1
Y= 3
3X = 1y
1. Write symbols of elements
2. Determine number of ions
X(+3) + y(-1) = 0
(Al+3 )x(Cl-1)y= 0
aluminum
What is the Lowest
If there
is no Roman
Common
Multiple “LCM” of
Numeral,
to know
3 andyou
1. need
Do not
worry
the fixed
oxidation
number of
about
the sign(+/-)
the positive ion.
Choose the lowest
set of integers that
satisfies the equation
chloride
Al1Cl 3
Formula
If there is only one Final
atom
the “1” is not shown
Next
Example #1-Names to Formulas
1. Write symbols of elements
aluminum chloride
2. Determine number of ions
(Al+3 )x(Cl-1)y
If there is no Roman
X(+3) + y(-1) = 0
Remember
allmust
compounds
Numeral,
you
know the
For
aluminum,
What
is
the
Lowest
This For
formula
says that
chloride,
are
neutral,
thus
oxidation
number
of
the “LCM” of
a
1
is
multiplied
Common
Multiple
the +3
of one Al
a 3charge
is multiplied
1(+3) + 3(-1) = 0
the
total
positive
charge
positive
ion.
times
the
+3
to
give
3
and
1.
Do
not
worry
atom
timeswill
thecancel
-1 tothe-3
give
must
equal
the
+3the
charge
about
charge
3 sign(+/-)
Cl atoms
aafrom
-3
charge
total negative charge
Al1Cl3
If there is
only
one atom
Final
Formula
the “1” is not shown
Next
Example #2-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X 1
Y= 2
2X = 1y
X(+2) + y(-1) = 0
(Co+2)x(BrO3-1)y= 0
cobalt(II) bromate
Choose the lowest
set of integers that
satisfies the equation
BrO3)2
Co1(BrO
If there Final
is only
one atom
Formula
the “1” is not shown
Next
Example #3-Names to Formulas
1. Write symbols of elements
X 1
Y= 3
3X = 1y
X(+3) + y(-1) = 0
2. Determine number of ions
(Ni+3)x(C2H3O2-1)y=
0
nickel(III) acetate
Choose the lowest
set of integers that
satisfies the equation
C2H3O2)3
Ni1(C
Formula
If thereFinal
is only
one atom
the “1” is not shown
Next
Example #4-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X 3
Y= 1
1X = 3y
X(+1) + y(-3) = 0
(Li +1 )x(PO4-3)y= 0
If there is no Roman
Choose
lowest
Numeral,
youthe
need
to know
set of
integersnumber
that of
the fixed
oxidation
the equation
the satisfies
positive ion.
lithium phosphate
PO4)1
Li3(PO
If thereFinal
is only
one atom
Formula
the “1” is not shown
Next
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.
Practice Problem #1
Fe(NO3)3
Choose the correct name for the compound
1. Iron trinitrate
2. iron(I) nitrate
3. iron(III) nitrite
4. iron(III) nitrate
5. none of the above
Periodic Chart
Polyatomic Ions
next problem
Practice Problem #2
sodium chlorite
Choose the correct formula for the compound
1. NaCl
2. NaClO
3. NaClO2
4. Na(ClO)2
5. none of the above
Periodic Chart
Prefixes
next problem
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
chromate
dichromate
oxalate
peroxide
SO3-2
CrO4-2
Cr2O7-2
C2O4-2
O2-2
Ions with a -3 Charge
phosphate
PO4-3
phosphite
PO3-3
arsenate
AsO4-3
Ions with +1 charge
ammonium ion NH4+1
return
Oxidation Numbers
(most common)
-2
-3
-4
+3
+2
+1
-1
0
1A
H 2A
Li
+1 +2
Be
Click on element to see its
oxidation number(s)
Na Mg
K
Ca Sc Ti
Rb Sr
+2 +3
Y
V
+2 +4 7A
3A 4A 5A 6A
8A
H
He
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Ce Ba La Hf Ta W Re Os Ir
Pt Au Hg Tl
Pb
Bi
I
Xe
Po At Rn
Fr Ra Ac Rf Db Sg Rh Hs Mt
return
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa
U
Np Pu Am Cm Bk Cf Es Fm Md No Lr