Chapter 9
Chemical Names and
Formulas
Ionic Compounds
Learning Targets:
I can …
• identify the charge of ions
• calculate the amounts of electrons
being transferred in an ionic bond
 explain the ratio between cations
and anions in an ionic compound
Vocabulary Terms
Monatomic ion- a single ion,
2+
1Ca or Cl
Binary Compound – made of
two different elements bonded
together
Why learning chemical nomenclature is important!
Death due to accidental inhalation of DHMO, even in small quantities.
Prolonged exposure to solid DHMO causes severe tissue damage.
Excessive ingestion produces a number of unpleasant though not typically
life-threatening side-effects.
DHMO is a major component of acid rain.
Gaseous DHMO can cause severe burns.
Contributes to soil erosion.
Leads to corrosion and oxidation of many metals.
Contamination of electrical systems often causes short-circuits.
Exposure decreases effectiveness of automobile brakes.
Found in biopsies of pre-cancerous tumors and lesions.
Given to vicious dogs involved in recent deadly attacks.
Often associated with killer cyclones in the U.S. Midwest and elsewhere,
and in hurricanes including deadly storms in Florida, New Orleans and other
areas of the southeastern U.S.
Thermal variations in DHMO are a suspected contributor to the El Nino
weather effect.
Chemical reactions occur and
bonds form if stability can be
increased.
Bonding
All of the elements on the periodic table
will try and achieve a stable arrangement
of electrons like the noble gases.
Bonding
All of the elements on the periodic table
will try and achieve a stable arrangement
of electrons like the noble gases.
They will do this by undergoing chemical
reactions and forming bonds with other
elements in order to gain or lose or share
electrons
Chemical Formulas
Show the kinds and numbers of atoms present
CO2
AlCl3
C6H12O
H2 O
NaCl
Ionic Compounds
Ionic bonds
form between
metals and
nonmetals by a
transfer of
electrons
Ionic Bonding
• The electron moves from the
metal atom to the nonmetal atom
• Opposite charges hold the ions
together
+
-
Metal
Nonmetal
Ionic compound:
A compound that results when a
metal reacts with a nonmetal to form
ions called cations and anions.
Ion:
Atoms that have gained or lost one
or more electrons to acquire a net
positive or negative electric charge
Na
11 p+
11 e-
Lose 1 e-
Na+1
11 p+
10 e-
Cations –
Positive ions formed when
metal atoms lose electrons
Ca+2
Na+1 Al+3
Cation name = name of
metal atom
Anions –
Negative ions formed when
nonmetal atoms gain electrons
Cl-1 S-2 N-3
Anion names end in -ide
Properties of Ionic Compounds
• Metal + nonmetal atoms
• Crystalline structure – Crystal lattice
• Ions are strongly bonded to each other
• Ionic compounds are
called salts (ex/ NaCl)
• Simplest ratio of ions is
called the formula unit
• The formula unit shows
the lowest whole number
ratio of the ions.
Ionic Bonding
Na Cl
The dots around the element
symbol are called Lewis Dots
and represent the VALENCE
electrons for the atom
Ionic Bonding
Na Cl
Sodium (Na) transfers its
ONE valence electron to
Chlorine (Cl) and gives
Chlorine a full octet
Ionic Bonding
Na Cl
+1
-1
Result is a positive Na ion
and a negative Cl ion that are
attracted to each other
(opposite charges)
NaCl
Formula
Unit
Nomenclature of Ionic Compounds
metal + nonmetal with “ide” ending
Why do elements gain or lose electrons?
(2)
1 outer e
2 outer e
Various #’s of outer e
8
3 4 5 6 7
How do we know the charges?
•
•
•
•
•
•
•
•
Group 1 elements – lose 1e = +1 charge
Group 2 elements – lose 2e = +2 charge
Group 13 elements – lose 3e = +3 charge
Group 14 elements – gain/lose 4 = +4/-4
Group 15 elements – gain 3e = -3 charge
Group 16 elements – gain 2e = -2 charge
Group 17 elements – gain 1e = -1 charge
Group 18 elements do not gain or lose
electrons!
Charges on monoatomic ions
+1
+4/-4
Transition metals can
+2 have a variety of
charges
+3
-3 -2 -1
0
Transition Metal Ions Stock System
– use roman numerals to denote charge
•
•
•
•
•
•
Fe2+
Fe3+
Cu+
Cu2+
Au+
Au3+
Iron (II)
Iron (III)
Copper (I)
Copper (II)
Gold (I)
Gold (III)
Special exceptions
Regular (non-transition) metals with multiple charges
•
•
•
•
Sn2+
Sn4+
Pb2+
4+
Pb
Tin (II)
Tin (IV)
Lead (II)
Lead (IV)
You MUST write roman numerals for these
elements
Memory aide- Roman soldiers carry tin(Sn)
and lead (Pb) shields.
Special exceptions
Transition metals with single charges
• Silver (Ag
2+
• Zinc (Zn )
+)
Do not write roman numerals for these elements
Polyatomic Ions
Ions that contain 2 or more
nonmetal elements
Groups of nonmetal atoms
that carry a charge
SO4
-2
sulfate ion
Some polyatomic ions
contain oxygen atoms and are named in
a special way
ate – 1 more oxygen atom
ite – 1 fewer oxygen atom
NO3
NO2
-1
-1
nitrate
nitrite
The prefix hypo – means under or too little
ClO
-1
Hypochlorite
ClO2 -1
Chlorite
ClO3 -1
Chlorate
ClO4 -1
Perchlorate
He prefix per means hyper – means above or
too much
Some polyatomic ions
end in -ide
CN
OH
-1
-1
cyanide
hydroxide
NH4
1+
Ammonium ion
The only + polyatomic ion
The only polyatomic cation
Writing Formulas for
Binary Ionic Compounds
2 elements only
(Type I)
Ionic compounds are neutral. Equal
#’s of electrons have been
transferred.
Na Cl
Ionic compounds are neutral. Equal
#’s of e have been transferred.
Na Cl
Ionic compounds are neutral. Equal
#’s of e have been transferred.
Na Cl
+1
-1
Ionic Compounds have zero net charge
Formula Unit
NaCl
Na+1 x 1
Cl-1 x 1
+1
-1
Al
Br
Al
Br
Al
Br
-1
-1
Al
Br
-1
-1
Al
Br
-1
-1
Al
+3
Br
-1
-1
3:1 Ratio between Al and Br
Creates a neutral compound
Formula Unit
AlBr3
Al3+ x 1
Br-1 x 3
+3
-3
Ca
P
Ca
P
+2
Ca
P
+2
Ca
Ca
P
+2
Ca
Ca
P
-3
+2
Ca
Ca
P
P
+2
Ca
+2
Ca
P
P
Ca
+2
Ca
P
+2
Ca
P
Ca
+2
Ca
P
+2
Ca
P
2+
Ca
2+
Ca
2+
Ca
P
P
3:2 Ratio between Ca and P
Creates a neutral compound
Formula Unit
Ca3P2
Ca2+ x 3
P3- x 2
+6
-6
Writing a binary chemical formula
3+
1-
Al
Br
Metal ion is always
written first
AlBr3
Writing a binary chemical formula
2+
Ca
3-
P
Metal ion is always
written first
Ca3P2
More Practice
• Magnesium and Sulfur
• Calcium and Bromine
• Potassium and nitrogen
• Aluminum and Oxygen
• Strontium and Phosphorous
Naming Binary Ionic Compounds
Type I
1. Name the metal ion (same as
metal atom)
2. Name the nonmetal ion (by
changing the ending and
adding -ide)
For cations (metal ions) simply
name the metal as usual:
•
Na+1
•
Al+3
For anions (nonmetal ions) –
change the ending to -ide
(may need to drop part of element name)
• N
-3
• O
• P-3
-2
Binary ionic naming examples:
• CaBr2
• K3N
• Sr3P2
calcium chloride
• barium oxide
• aluminum sulfide
• lithium selenide
CaCl2
BaO
Naming Type II Compounds
Stock system (Roman Numerals)
for Transition metals
1. Determine if 1st element is a
transition metal
2. If yes, use roman numerals when
naming
Don’t Forget the Exceptions!
• Silver (Ag) and Zinc (Zn) do
not get a roman numeral
• Lead (Pb) and Tin (Sn) must
have roman numerals
Stock System
(for transition metals)
•
•
•
•
•
•
Copper (II) chloride =
Copper (I) chloride =
Iron (III) chloride =
Iron (II) chloride =
Tin (IV) chloride =
Tin (II) chloride =
Ternary Compounds:
(w/ polyatomic ions)
(Type I or II)
• Formed from a metal cation
and a polyatomic anion
• Contain 3 or more different
elements in the formula
• Use ( ) around polyatomic ions if
there is more than 1. Al(NO3)3
Na 1+ OH 1
NaOH
Not Na(OH)
Mg 2+ OH 1
Not MgOH2
Mg(OH)2
Naming Ternary compounds:
1. Name the metal cation
2. Name the polyatomic ion
K
+1
KNO3
NO3
-1
K
+1
NO3
-1
KNO3
Potassium nitrate
Ca
2+
PO4
Ca3(PO4)2
3
Ca
2+
PO4
Ca3(PO4)2
3
NH4
1+
SO3
(NH4)2SO3
2-
NH4
1+
SO3
2-
(NH4)2SO3
Ammonium sulfite
Cu
2+
SO4
CuSO4
2-
Cu
2+
SO4
2-
CuSO4
Copper (II) sulfate
Fe
2+
NO2
-1
Reviewing Ionic Formulas
• In an ionic formula the net charge is zero
• An –ide ending usually indicates a binary
compound (two elements – metal and nonmetal)
• Exceptions: cyanide, peroxide, hydroxide
• An –ate or – ite ending indicates a polyatomic ion
that has oxygen in the formula
• ate = more oxygens ite = fewer oxygens
Reviewing Ionic Formulas
• A roman numeral after the name of a cation
shows the ionic charge on the transition
metal cation
• Ions in the same group have similar formulas
(due to the same number of valence
electrons)
• Use ( ) around polyatomic ions if there is
more than one*
Ca3(PO4)2
* if there is only one, do not use ( )
Naming Molecular
Compounds
(Covalent)
Type III
Nonmetal + Nonmetal
The Covalent Bond
Sharing of electrons
Properties of Molecular or Covalent
Compounds
• Made from 2 or more nonmetals
• Consist of molecules not ions
Molecular Formulas
Show the kinds and numbers of
atoms present in a molecule of a
compound.
Molecular Formula = H2O
Structural formula
H N H
H
Molecular formula
NH3
Molecular Formulas
• Examples
• CO2
• SO3
• N2O5
Rules for Naming
Molecular compounds
• The most “metallic” nonmetal
element is written first (the one that
is furthest left)
• The most nonmetallic of the two
nonmetals is written last in the
formula
• NO2 not O2N
• All molecular compounds end in
-ide
Molecular compounds
• Ionic compounds use charges to
determine the chemical formula
• The name of the molecular compound
indicates the chemical formula.
• Uses prefixes to tell you the quantity of
each element.
• You need to memorize the prefixes !
Prefixes
•
•
•
•
•
•
•
•
•
•
1 mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nona
10 deca
Memorize!
More Molecular Compound
Rules
• If there is only one of the first element do
not put mono
Example: carbon monoxide (not monocarbon monoxide)
• If the nonmetal starts with a vowel, drop
the vowel ending from all prefixes except
di and tri
• monoxide not monooxide
• tetroxide not tetraoxide
Molecular compounds
N2O5
Molecular compounds
N2O5
di
Molecular compounds
N2O5
dinitrogen
Molecular compounds
N2O5
dinitrogen
penta
Molecular compounds
N2O5
dinitrogen
pentaoxide
Molecular compounds
N2O5
dinitrogen
pentaoxide
Molecular compounds
N2O5
dinitrogen
pentoxide
dinitrogen pentoxide
Molecular compounds
Sulfur trioxide
Molecular compounds
Sulfur trioxide
S
Molecular compounds
Sulfur trioxide
S
Molecular compounds
Sulfur trioxide
S
O3
Molecular compounds
Sulfur trioxide
S
O3
SO3
Molecular compounds
CCl4
Molecular compounds
CCl4
monocarbon
Molecular compounds
CCl4
monocarbon
Molecular compounds
CCl4
carbon
Molecular compounds
CCl4
carbon
tetra
Molecular compounds
CCl4
carbon
tetrachloride
Molecular compounds
CCl4
carbon
tetrachloride
Carbon tetrachloride
Write molecular formulas
for these
• diphosphorus pentoxide
• trisulfur hexaflouride
• nitrogen triiodide
Common Names
H2 O
NH3
Common Names
H2 O
NH3
Water
Ammonia
Names and Formulas
for Common Acids
(memorize these)
•
•
•
•
HCl
HNO3
H2SO4
H3PO4
Hydrochloric Acid
Nitric Acid
Sulfuric Acid
Phosphoric Acid