U7D2
Writing and Naming Ionic Formulas
U7D2: Writing and Naming Ionic Formula
HW: WS: Formula Writing and Naming Practice
Do Now: 1.HW out for check
2. Is [Cd]-2 the correct ion dot diagram for a
Cadmium ion? Explain.
Today:
• Review
• Naming Ionic Compounds
• Practice!!!
• TTL
The three steps in forming an ionic bond are:
Metal loses e- to nonmetal becoming a cation.
1. ____________________________________________
Nonmetal gains e- from metal to become an anion.
2. ____________________________________________
Cation and anion attract to form an ionic compound.
3. ____________________________________________
Period 1
Let’s practice
More????
• So.. Fist to Five
Fist (not understanding need help)
Five (feel I can teach it)
• Show me where you stand
Ionic Formula Writing
• The number of each type of ion that will form the
new compound will depend on the size or magnitude
of the charges (oxidation states).
• The charges must add up to zero.
• Ex. sodium reacts with chlorine,
• sodium forms a Na+1 ion & chlorine forms a Cl-1 ion.
• Only one of each ion is necessary ->
•
the charges add up to zero: (+1) + (-1) =0
the formula of the new compound, sodium chloride,
is simply NaCl.
but what if the charges aren’t equal and
opposite?
• If sodium reacts with oxygen,
• sodium still forms a Na+1 ion but oxygen forms a
O-2 ion.
• The new compound, sodium oxide, will require 2
Na+1 for every O-2:
2(+1) + (-2) =0 .
• The formula for sodium oxide is Na2O.
Remember:
• the charges are written as superscripts (Na+1)
and the counters in formulas are written as
subscripts (Na2O).
• Positive ions are written first and negative ions are
written second in a formula.
• Lazy chemists do not bother to write 1 as counter in
a formula. The element's symbol stands for the 1.
• Ionic formulas are always written in lowest
terms. => an empirical formula.
• NaCl and Na2O are binary (2 element) ionic cds.
VI. DETERMINING CHARGES:
• The oxidation state or number is the charge or
apparent charge an atom has in a compound.
• To determine the charge, simply look at the
Periodic Table for the oxidation states of the
element.
• For nonmetals it is the FIRST (top) oxidation
state ONLY.
• For many metals, there is only one possibility for
the charge.
• Transition metals and those metals close to
the “crack”, there are more than one charge.
Look up the charges on the following:
• Remember to write the charges as superscript
Sr+2
-2
O
Ag
Cl
+1
+2
Fe
+3
Fe
+1
Cu
-1
+2
Cu
-3
N
P
+3
Cs
+1
-1
Br
Draw a Lewis Dot structure for (p. 3 margin)
FeO
and
Fe2O3
WRITING BINARY FORMULAS
• The ions of the elements combine in such a way that
the charges have to add up to zero.
• Metal or positive ion (cation) is written FIRST
• Nonmetal or negative ion(anion)is written SECOND.
• The number one,1, is not written in the formula
ex. NaCl.
• Only the number in the charge for each ion is criss-
crossed down and turned into subscripts.
• Always check that the formula is in LOWEST terms.
• K+1 O-2  K
O

K2O1 or K2O
PbO2
• Pb+4 O-2 -> Pb O -> Pb2O4 simplifies to ______
So… Let’s look at the different
combinations we can have…
Ions to be
Bonded
How to determine formula
X+1 & Y-1
+1 and -1 add up to zero already
XY
X+2 & Y-2
+2 and -2 add up to zero already
XY
+3 and -3 add up to zero already
XY
It takes two -1 charges to cancel
out the +2 charge
It takes three -1 charges to cancel
out the +3 charge
XY2
+3
X
&Y
-3
X+2 & Y-1
X+3 & Y-1
Formula
XY3
Ions to be
Bonded
X+1 & Y-2
How to determine formula
It takes two +1 charges to cancel out the
-2 charge
+1
-3 It takes three +1 charges to cancel out
X &Y
the -3 charge
+2
-3 Common denominator: 2x3=6 it takes
X &Y
three +2 to make +6 and two -3 to make
-6
X+3 & Y-2 Common denominator: 2x3=6 it takes two
+3 to make +6 and three -2 to make -6
+4
-2 It takes two -2 charges to cancel out the
X &Y
+4 charge
Formula
X2Y
X3Y
X3Y2
X2Y3
XY2
VII. NAMING
•
The name of the positive ion is followed by the
name of the negative ion.
• Group 1 & 2 Metals, Metals with ONE charge
LISTED: name of the metal ONLY
• For nonmetals, the ending of the nonmetal’s name
with the ending changed to IDE.
Let’s try!
• Name ionic compounds:
• NaF:
sodium fluoride
• AlN:
Aluminum nitride
• AgBr:
Silver bromide
• Na3P:
sodium phosphide
• Li2O:
Lithium oxide
• PbCl2 : Lead (II) chloride
Practice
ex.
1.)
2.)
3.)
4.)
5.)
Cation
Mg+2
+1
Li
Al+3
Sr+2
K+1
Mg+2
Anion Formula Name
Br-1 MgBr2 Magnesium Bromide
-1
LiF
Lithium fluoride
F
AlCl3
Aluminum chloride
Cl-1
Strontium sulfide
SrS
S-2
Potassium nitride
K3N
N-3
Magnesium phosphide
Mg3P2
P-3
How about backwards? Name -> formula
• Determine the elements involved, their charges &
then write the formulas. Look up charges on the PT
for the ions.
Name
Cation Anion Formula
Na+1
NaBr
Br-1
1.) Sodium Bromide
2.) Calcium Oxide
Ca+2
O-2
CaO
3.) Zinc Chloride
Zn+2
Cl-1
F-1
ZnCl2
I-1
KI
4.) Beryllium Fluoride
5.) Potassium Iodide
Be+2
K+1
BeF2
VIII. DETERMINING CHARGES AND
NAMING of TRANSITION ELEMENTS
• Transition elements (metals) and some other
metals located near the “crack”, can have more
than one charge.
• Either you will be told which one to use or the
charge can be determined from the formula.
• To distinguish between the different oxidation
states or charges, a roman numeral equal to
the charge on the ion is used to name the ion.
• Ex, tin comes in two charges, +2 and +4.
• Sn+2 is called tin (II) and Sn+4 is called tin (IV).
• The formula of tin (II) oxide is SnO and
• the formula of tin (IV) oxide is SnO2.
• The charge on the tin makes a difference!
• If Fe2O3 is iron (III) oxide, what would be the
FeO
formula for iron (II) oxide? _____
• (Draw the Ion dot diagram for
Iron (II) oxide)
ROMAN NUMERALS:
III +4 ____,
VI
IV +5 ____,
+1 ___,
+3 ____,
I +2 ____,
II
V +6 _____
Write the formula and name of these compounds with transition metals:
Cation Anion Formula Name
+2
-1
ex. Pb
Cl
PbCl2
lead (II) chloride
+1
-2
1. Cu
O
Cu2O
Copper (I) oxide
2.
Ni+3
S-2
Ni2O3
Nickel (III) sulfide
3.
Fe+2
I-1
FeI2
Iron (II) iodide
4.
Au+1
N-3
Au3N
Gold (I) nitride
5.
Pb+4
O-2
PbO2
Lead (IV) oxide
Going Backwards!
Roman numerals tell you what charge to use for the metal (first
element): gold (III) chloride tells you to use Au+3 and NOT Au+1
Name
ex. Iron (II) iodide
Cation Anion Formula
Fe+2
I-1
BaI2
1.
Copper (I) fluoride
Cu+1
F-1
CuF
2.
Copper (II) chloride
Cu+2
Cl-1
CuCl2
3.
Gold (III) oxide
Au+3
O-2
Au2O3
4.
Tin (IV) oxide
Sn+4
O-2
SnO2
5.
Lead (II) phosphide
Pb+2
P-3
Pb3P2
Naming the Ionic Compounds from
JUST the Formula
• Determine if it has a metal with more than 1 charge or not
• If yes, then look up the nonmetal’s charge and write the formula
•
•
•
•
•
•
•
•
•
•
with each of the charges.
Ex . FeO
Fe+2
O-2  FeO
Fe+3
O-2  Fe2O3
a) Since the formula with Fe+2 matches, FeO, then Fe+2 was used.
Use the Roman numeral equal to this charge in the middle of the
compound’s name. Iron (II)
b) Change the name of the non-metal to the ending “ide”. Oxide
Iron (II) Oxide
If no, then just use the metal’s name and change the name of the nonmetal to the ending “ide”.
Ex.
AgCl
Ag+1 +1 is the only charge
Silver Chloride
• Remember any element in Groups 1 & 2 have ONLY one Charge!! No
Roman Numeral ever!!!
Formula Name
Formula
Name
AgCl
Fe2O3
Iron (III) oxide
PbO2
SnO
Silver chloride
AuI
3
Lead (IV) oxide
CrN
Tin (II) oxide
Gold(III) iodide
Chromium(III) Nitride
Na3P Sodium phosphide CuO
Copper(II) oxide
ZnBr2
Calcium nitride
Zinc bromide
Ca3N2
IX. POLYATOMIC IONS (PAI)
• A. Reference Table E
• Groups of atoms bond
together by sharing
electrons to form ions.
• one of the atoms in the
group brings along a
charge and group of
atoms is not neutral
• “many atom” ion.
Complete this chart using reference table E.
Polyatomic
Ion name
ex.
1.
Formula
Polyatomic
Ion Formula
Name
Ammonium NH4+1 ex. MnO4 - Permanganate
-2
6.
Nitrate
CO
carbonate
3
NO
3
7.
C
H
O
2 3 2
ClO2
2.
Chlorite
3.
Chromate CrO4 -2 8.
SO4-2
sulfate
4.
Sulfite
ClO3-
chlorate
5.
Phosphate PO4 -3 10.
SO3 -2 9.
OH
-
acetate
hydroxide
• What type of charge do most of the PAI have?
__________________
negative
-ite
-ate
• Most of these PAI end in _________ or __________
• Two important exceptions are the positive ion
+
NH
4
_________
(ammonium) and the negative ion
_________
(hydroxide).
OH-
B. Writing and Naming Compounds
with Polyatomic Ions
Rules:
• The formula must be in lowest terms
• the charges must add up to zero.
• Parenthesis are used around the polyatomic ion when
more than one of these ions is necessary in a formula:
(NH4)2O.
• To name compounds with polyatomic ions, use the name of
the polyatomic ion listed on the reference table.
• Ex: (NH4)2O is ammonium oxide;
•
K2CO3 is potassium carbonate.
• ternary ionic compounds:
• binary ionic compounds:
K2CO3 and NaClO4
K2O and NaCl
Try your hand at these!
Cation
Anion
1.
K+1
NO3 -1
2.
Al+3
ClO3 -1 Al(ClO3)
3.
Sr
+2
4.
K+1
NO2 -1
5.
Mg+2
PO4
Mg+2
ClO-1
SO4
-2
-3
Formula
Name
Mg(ClO)2 Magnesium hypochlorite
KNO3
Potassium nitrate
Aluminum chlorate
3
SrSO4
Strontium sulfate
KNO2
Potassium nitrite
Mg3(PO4)2 Magnesium phosphate
Going Backwards! ternary compounds
Name
Anion
Formula
ex.
Beryllium nitrite
Cation
1.
Sodium hydroxide
Na +1 OH -
NaOH
2.
Calcium sulfate
3.
Be+2
(NO2)-1 Be(NO2)2
Ca +1 SO2 -2
Potassium chromate K +1 CrO -2
4
4.
5.
Gold (III)
carbonate
**Ammonium
perchlorate
CaSO4
K2CrO4
Au +3 CO3 -2
Au2(CO3)3
NH3 + ClO4 -
NH3ClO4
Ok…so how’d we do today
1.
• Cation:__Ag+1__
Anion:___ (OH)-1____
• Formula:___________________
• Name:_____________________
• 2.
• Cation:____ Fe+3__
Anion:___ (PO4)-3___
• Formula:___________________
• Name:_____________________