Naming Compounds and
Writing Formulas
Key
Question:
Why Do Atoms Combine In Certain Ratios?
Review of Oxidation Numbers
Chemical Compound Quiz
Sodium chloride is a flavorful addition to many
foods. What is the common name?
Salt
Review of Oxidation Numbers
 All
compounds have an electrical charge of zero
(they are neutral).
 An oxidation number indicates the charge on the
atom (or ion) when electrons are lost, gained, or
shared in chemical bonds.
Oxidation Numbers
A
sodium atom always ionizes
to become Na+ (a charge of
+1) when it combines with
other atoms to make a
compound.
 Therefore, we say that sodium
has an oxidation number of 1+.
What is chlorine’s oxidation number?
H
He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
1 2 3 4 5 6 7 8
The Number Of Electrons In The
Outside Energy Level.
You Might Be a hittite if…
You take your dog for a walk and
both use the same tree.
You burn your yard rather than mow
it.
Ionic Bonds
 On
the periodic table, strong electron donors are on the
left side (alkali metals).
 Strong electron acceptors are on the right side
(halogens).
 The further apart two elements are on the periodic table,
the more likely they are to form an ionic compound.
Covalent Bonds
 Covalent
compounds form when elements have roughly
equal tendencies to accept electrons.
 Elements that are both nonmetals and therefore close
together on the periodic table tend to form covalent
compounds.
Oxidation Numbers, Lewis Structures And
Chemical Formulas
 Remember,
the oxidation numbers for all the atoms in a
compound must add up to zero.
Multiple Oxidation Numbers
 Some
periodic tables list
multiple oxidation numbers
for most elements.
 This is because more
complex bonding is possible.
Naming Compounds and
Writing Formulas
Naming Binary Ionic Compounds:
At the conclusion of our time together, you
should be able to:
1. Name a binary ionic compound with a metal
that has one oxidation number using
standard naming procedures
2. Name a binary ionic compound with a metal
that has multiple oxidation numbers using
the Roman system
3. Write the formula of a binary ionic compound
if given the name
6 Types Of Chemical Compounds
•Binary ionic
- metal ion – nonmetal ion
•Binary molecular - two nonmetals
•Ternary ionic
- at least one ion is a
polyatomic ion
•Binary acid
- H – nonmetal
•Ternary acid
- H – Polyatomic ion
•Base
- metal ion – OH
Naming Compounds with Ionic Bonds
Tips To Keep In Mind When Naming And Writing
Formulas:
•Always keep your Periodic Table handy – You should
have it in front of you ALWAYS when you are naming and
writing formulas.
•Remember that metals (except Hydrogen) are found to the
left of the stairstep on the Periodic Table.
•Nonmetals are found on the right side of the stairstep of
the Periodic Table.
•Metalloids are the 6 elements on or below the stairstep
except Al, Po and At. For naming purposes they will tend
to behave like nonmetals.
Naming Binary Compounds
A
binary ionic compound is held together by ionic
bonds. Consider a metal with a nonmetal to be this
when naming.
 Binary molecular compounds consist of covalently
bonded atoms. Consider a metalloid/nonmetal with a
nonmetal to be this when naming.
 Each type of compound has its own naming rules.
How Do You Name Binary Ionic Compounds?
(Composed Of Two Elements – A Metal And A
Nonmetal)
•Name the first ion
•From groups 1, 2, 3, 13, zinc, cadmium, or silver.
(You must use a Roman Numeral with the name for
the other metals – we’ll discuss this later.)
•Name the second ion changing the suffix to –ide.
Naming Binary Ionic Compounds
 MgBr2 is
magnesium (name
of first element) + brom (root
name of second element) +
ide suffix = magnesium
bromide
Examples
NaCl
Sodium Chloride
CaO
Calcium Oxide
Al2S3
Aluminum Sulfide
MgI2
Magnesium Iodide
Name the metal ion
Name the nonmetal ion,
changing the suffix to –ide.
Hittite Hotel!
Examples
This is two metals – not a binary ionic
BaNa2 You
Theshould
name recognize
of this is Banana
a problem
(haha!!)
with this
compound
one
What is the name of this
compound:
HIJKLMNO?
WATER – “H” to “O”
You have to admit – that was
funny!
Exit Quiz
LiCl
Lithium Chloride
Name the metal ion
CaSe
Calcium Selenide
Name the nonmetal ion, changing
the suffix to –ide.
Ga2S3
Gallium Sulfide
MgF2
Magnesium Fluoride
What About The Transition Metals And Using Roman
Numerals? How Does That Work?
Let’s See.
FeO
Iron(II)
Oxide
Notice – metal and nonmetal.
Name the first ion. Since the first ion is a transition
element, you must use a Roman Numeral to
represent the charge.
How do you know the charge?
Deductive reasoning.
•All compounds are neutral.
•Oxygen has a -2 charge (group 16)
Isn’t this easy
and FUN!!!
•Therefore, iron must have a +2 charge since there
is one iron and one oxygen. Iron gets a Roman
Numeral (II).
Cu2S
Name the first ion. Since it is a transition metal, you
must use a Roman Numeral.
Which Roman Numeral? The Roman Numeral is the
same as the charge of the ion.
How do you find the charge?
Deductive reasoning!
•All compounds are neutral
•Sulfur has a -2 charge (group 16)
•There are two coppers
Copper (I)
•Therefore each copper must have a +1 charge for the
Sulfide
compound to be neutral
MnO2
Name the first ion. Since it is a transition metal,
you must use a Roman Numeral.
How do you determine the Roman Numeral?
Manganese (IV)
oxide
It is the same as the charge.
What is the charge of Mn?
•Oxygen (group 16) has a -2 charge and a total
of -4 charge.
•There are two oxygens with one manganese.
•Therefore Mn must have a +4 charge for this
compound to be neutral.
Things You Can Learn
From Your Dog!!
•
When it is hot outside, drink lots of water.
•
Take naps.
So Why Must We Use Roman Numerals With
Transition Elements?
•The metals in groups 1, 2, 3, and 13 have single, definite charges.
•Group 1 metals have a +1 charge.
•Group 2 metals have a +2 charge.
•Groups 3 and 13 metals have a +3 charge.
•Transition metals may have multiple charges – usually two different
positive charges.
For example, there are two copper oxide compounds:
_____
____
Cu2O and CuO
Copper (I
(II)) oxide
Copper is +1
+2
We can’t just say Copper oxide. Which one of
these is Copper oxide? We must distinguish these
by using a Roman Numeral
And Remember, There Are Three Transition Elements
Which Do Not Require A Roman Numeral Because They
Have Single Definite Charges. These Are:
Zinc – Zn2+
Cadmium – Cd2+
Silver – Ag+
You need to remember the charges for these.
Ag2O
Name the first ion.
Silver oxide
Name the second ion changing the
suffix to –ide.
No Roman
Numerals needed
Name the first ion.
for these.
ZnCl2
Zinc chloride
Name the second ion changing the
suffix to –ide.
How Do You Write Formulas For Binary Ionic Compounds
Given The Name?
Two Simple Steps:
1. Write the symbol and charge of each ion
2. Balance the charges by providing subscripts
Magnesium
chloride
Mg2+
MgCl2
ClCl-
Write the symbol and charge of each ion
Balance the charges by supplying
subscripts. Subscripts tell how many of
each atom is present.
You need a second Cl-1 to balance the
charges
Iron (III) bromide
Fe3+
Br Br Br FeBr3
Write the symbol and charge of each ion.
The charge of the iron is provided by the
Roman Numeral.
Balance the charges by supplying
subscripts. The subscripts tell how many
of each ion is needed to balance the
compound.
You’ll need three bromine ions to balance
the one iron.
Aluminum Sulfide
Al3+
Al3+
Al2S3
S2S2S2-
Write the symbol and charge of each ion.
Balance the charges by supplying subscripts.
In this case the charges do not evenly divide
into each other. You must find the least
common multiple. SIX
How many aluminums are needed to arrive at
a +6 charge?
2
How many sulfurs are needed to arrive at a -6
charge?
3
Jobs you get with a Chemistry Major
Writing Formulas a Little Quicker
Iron and oxygen combine to form a compound. Iron (III)
(Fe) has an oxidation number of 3+. Oxygen (O) has
an oxidation number of 2–.
Predict the chemical formula of this compound.
Writing Formulas a Little Quicker
3+
2-
Fe 2 O 3
Simply cross the oxidation numbers
and make them positive
Let’s Try Another One:
Manganese (IV) phosphide
4+
3-
Mn 3 P 4
Let’s Try One More:
Manganese (IV) oxide
4+
2-
Mn 2 O 4
MnO2
Cross but in
this case they
must be
dropped!
Naming Binary Ionic Compounds:
Let’s see if you can:
1. Name a binary ionic compound with a metal
that has one oxidation number using
standard naming procedures
2. Name a binary ionic compound with a metal
that has multiple oxidation numbers using
the Roman system
3. Write the formula of a binary ionic compound
if given the name
Exit Quiz – Formula for magnesium chloride?
2+
MgCl2
1-
Exit Quiz – Formula for sodium oxide?
1+
Na2O
2-
Exit Quiz – Name for:
6+ 6-
3+ 2-
Fe2O3
Iron (III) oxide
Exit Quiz: Formula for Chromium (IV) oxide
4+ 2-
Cr O
2
4
CrO2
Murphy's Laws
of
Science and Technology
Logic is a systematic method of coming to the wrong
conclusion with confidence.
Naming Compounds and
Writing Formulas II
6 Types Of Chemical Compounds
•Binary ionic
- metal ion – nonmetal ion
•Binary molecular - two nonmetals
•Ternary ionic
- at least one ion is a
polyatomic ion
•Binary acid
- H – nonmetal
•Ternary acid
- H – Polyatomic ion
•Base
- metal ion – OH
Naming Binary Molecular and Ternary
Ionic Compounds:
At the conclusion of our time together, you
should be able to:
1. Name a binary molecular compound
2. Name a ternary ionic compound with a metal
that has one and multiple oxidation
numbers using the appropriate system
3. Write the formula of a binary molecular and
ternary ionic compound if given the name
The Second Category of Compounds –
Binary Molecular
What are Binary Molecular Compounds?
These compounds contain two elements (binary).
•The term “molecular” indicates that these elements are
joined by a covalent bond.
•They must therefore be nonmetals.
•Bottom line – 2 elements – both nonmetals
•To name and write formulas for these, you must know
some numerical prefixes.
Naming – You Must Use Prefixes.
1 = mono
3 = tri
5 = penta
7 = hepta
9 = nona
2 = di
4 = tetra
6 = hexa
8 = octa
10 = deca
Steps
1. The first nonmetal only gets a numeric prefix when there
is more than one. No prefix if there is only one.
2. The second element always gets a numeric prefix and
always has a suffix of -ide
Naming Binary Molecular Compounds
 As
with binary ionic compounds, the ending of the name of
the second element in the compound is modified by adding
the suffix –ide.
Familiar Saying
Socially orientated individuals tend to congregate in
gregariously homogenous groupings.
Birds of a feather flock together!!
CO2
Carbon dioxide
CO
Name the first element. Since there is
only one, no prefix is needed.
The second element always gets a prefix
and a suffix of –ide.
Carbon monoxide
N2O4
Dinitrogen tetroxide
H2O
Dihydrogen monoxide
CCl4
Carbon tetrachloride
Name the first element. Since
there are two present, the prefix
“di” is needed. The second
element always gets a prefix and
a suffix of –ide.
What do you think about this one???
AlCl3
Be careful. This is a metal and nonmetal.
Always keep your Periodic Table in front of
you for reference.
You may have been tempted to say
“aluminum trichloride”. This is
INCORRECT!
This is a binary IONIC compound. No
prefixes are used. Simply name it
aluminum chloride.
Given The Names Of Binary Molecular
Compounds, How Do You Write The Formulas?
Very easily done!!! The prefixes tell you how to write
the formulas. DO NOT CONSIDER CHARGES.
NONMETALS ARE ALL NEGATIVE SO TO USE
CHARGES DOES NOT WORK!
Silicon dioxide
Silicon and oxygen are both nonmetals.
SiO2
The lack of a prefix on silicon means
that there is only ONE silicon.
The prefix “di” in front of oxide means
that there are TWO oxygens.
Diphosphorous pentachloride
P2Cl5
Phosphorous and chloride are both
nonmetals.
The prefix “di” means that there are TWO
phosphorouses (Is that a word?)
The prefix “penta” before chlorine means
that there are five chlorines.
Nitrogen monoxide
NO
Nitrogen and oxygen are both
nonmetals.
The lack of a prefix on nitrogen
means only ONE nitrogen.
The prefix “mono” on oxygen
indicates ONE oxygen.
Is this not sooooooo easy!??
A Flow Chart For Naming Binary Compounds
Hittite Innovations
Mr. T
My Students
Third Category Of Compounds –
Ternary Ionic Compounds.
These Compounds Contain At Least One
Polyatomic Ion.
What is a polyatomic ion?
Let’s look at the name to try to understand.
•It is an ion – that means it has a charge.
•It is polyatomic – that means it is made of more than one
atom.
Let’s look at some examples of polyatomic ions.
CO32- carbonate
This ion is composed of one carbon
and three oxygens and the entire group
has a charge of -2.
Polyatomic ion – Group of atoms that act as a unit and
carry a charge.
You have been given a list of other polyatomic ions
You need to learn these!!!
How Do You Recognize Ternary Ionic Compounds?
Composed of two ions in which at least one is a
polyatomic ion.
There is only one positive polyatomic ion (NH4+1)
Three possible types of Ternary Ionic Compounds:
Polyatomic Ion
•Ammonium
+ negative ion (nonmetal)
•Metal (positive ion)
+ negative polyatomic ion
•Ammonium
+ negative polyatomic ion
Naming Compounds with Polyatomic Ions as
Cations
 NH4Cl
is ammonium (the
name of the ion from chart) +
chlor (root name of the
second element) + ide suffix
= ammonium chloride.
Naming Compounds with Polyatomic Ions as
Anions
1. Name the first ion.
2. Name the second ion. Isn’t that simple??!!
Examples:
Na2CO3
Sodium
carbonate
When you look at this compound you should
recognize that this is NOT binary. There are
THREE elements present. When you see this,
immediately look for a polyatomic ion.
Carbonate is present here.
Notice that you do NOT
change the suffix – just
name the polyatomic
ion
Name the first ion.
Name the second ion.
Fe(OH)3
Iron (III)
hydroxide
Since there
are 3 OH
groups, each
with a -1
charge, the
charge of the
iron must be
+3 for the
compound to
be neutral
Name the first ion.
Remember that iron requires a Roman
Numeral since it is a transition element.
What Roman Numeral should be used?
The Roman Numeral comes from the
charge of the ion. How do you find the
charge of the iron?
You know two things:
•All compounds are neutral.
•You know the charge of OH (-1)
Name the polyatomic ion.
NH4Cl
Name the first ion.
Ammonium chloride
Name the second ion.
Notice that since the second ion is a nonmetal that, like
binary ionic compounds, the suffix of the nonmetal
changes to –ide.
Looks like a monster, but it’s really a pussycat.
Naming Compounds with Polyatomic Ions as
Cations and Anions
(NH4)3PO4
Name the first ion.
Ammonium
phosphate
Name the second ion.
Cu2SO4
Copper (I) sulfate
Name the second ion.
Name the first ion.
You should realize that you
need a Roman Numeral since
copper is a transition metal.
The Roman Numeral is the same
as the charge.
What is the charge?
The charge of sulfate is -2.
Since there are two coppers, the
charge of the copper must be +1.
Euphemisms in Science
We all know that some politicians and government spokesmen
use certain euphemistic phrases to give an aura of respectability
to descriptions of events or actions which would be offensive
when expressed in plain English. The following is a list of
Euphemisms in Science and their translations into plain English.
“It has long been known...”
I haven't bothered to look up any references!
How Do You Write Formulas For Ternary Ionic
Compounds?
Very Much Like Writing Formulas For Binary Ionic
Compounds.
Three Steps:
1. Write the formulas/symbols of each ion.
2. Balance the charges by supplying subscripts.
3. If a subscript is needed for a polyatomic ion, it must be
put in parentheses with the subscript on the outside.
Let’s do some!!
Aluminum nitrate
Al3+
NO3-
Al(NO3)3
First, you can tell from the name
that there is a polyatomic ion
present (nitrate). All binary ionic
compounds have suffixes of –ide.
Write the formula/symbol and charge of each ion.
Balance the charges by supplying subscripts.
Since Al is +3 and NO3 is -1, you need a total of 3NO3to balance one Al3+
Since you will need a subscript of 3 for NO3-, you need
to put this in parentheses with the 3 outside.
Lead (IV) acetate
Pb4+
C2H3O2-
Pb(C2H3O2)4
Calcium phosphate
Ca2+
PO43-
Ca3(PO4)2
Write the formula/symbol and charge of
each ion.
Balance the charges by supplying
subscripts. Since Pb is +4 and C2H3O2 is 1, you will need 4 C2H3O2-1 to balance
1Pb+4
Write the formula/symbol and charge of
each ion.
Balance the charges by supplying
subscripts. Since Ca is +2 and PO4 is -3,
you will need 3 Ca+2 to balance 2 PO4-3
Strategy For Naming Ternary Ionic
Compounds.
What Do You Call A Detective Crossed With
A Inner Transition Metal?
Sherlock Holmium
Naming Binary Molecular and Ternary
Ionic Compounds:
Let’s see if you can:
1. Name a binary molecular compound
2. Name a ternary ionic compound with a metal
that has one and multiple oxidation
numbers using the appropriate system
3. Write the formula of a binary molecular and
ternary ionic compound if given the name
Exit Quiz
CO2
SO3
Carbon dioxide
Sulfur trioxide
SO
CO
Sulfur monoxide
Carbon monoxide
N2O5
B2O3
Dinitrogen pentoxide
Diboron trioxide
CF4
NF5
Carbon tetrafluoride
Nitrogen pentafluoride
Exit Quiz
 Al3+
combines with sulfate (SO4)2– to make aluminum
sulfate.
 Write the chemical formula for aluminum sulfate.
Exit Quiz Answer
3+
2-
Al 2 (SO4) 3
Let’s Try Another One:
Manganese (IV) phosphate
4+
3-
Mn3 (PO4)
4
Let’s Try One More:
Manganese (IV) carbonate
4+
2-
Mn (CO3)
2
4
Mn(CO3)2
Familiar Saying
It is fruitless to attempt to indoctrinate a superannuated
canine with innovative maneuvers.
You can’t teach an old dog new tricks!