Chem 11
Exam 3 Review
November 13, 2006,
Exam Topics
•
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•
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Naming compounds
Writing formulas
Ion names and charges
Balancing equations
Recognize ionic and covalent
Use Lewis structures to get
bonds and lone pairs
• Electronegativity
• Isoelectronic/Identical to
Nomenclature Terms
 Binary Compound :
contains 2 elements
 Binary Ionic Compound :
a metal and a nonmetal
-> metal named first
If metal has more than one
charge must indicate charge with
(Roman numerals) or
Latin endings
-ous
- ic
= lower charge
= higher charge
Nomenclature Terms
Binary Covalent Compound:
two nonmetals
Least electronegative element
named first
Second element has -ide ending
Greek prefixes indicate subscripts
1
2
3
4
5
=
=
=
=
=
monoditritetrapenta-
6 = hexa7 = hepta8 = octa9 = nona10 = deca-
Nomenclature Terms
Nonbinary Compound:
more than two elements
-
probably contains polyatomic
ion(s)
-
Name the polyatomic cation first
Name the polyatomic anion second
-
MUST KNOW the polyatomic ions
by name and formula to recognize
them 
Nomenclature Flow Chart
Nonmetal name
with –ide ending
Name the polyatomic
ion
+ 2 nonmetals
+ 1 nonmetal
Name the metal
Indicate metal charge
by (Roman #) or Latin
name (-ous or –ic)
Single-Charge
Metal
Multiple-Charge
Metal
*Metal + Nonmetal
Chemical Formula
2 Nonmetals
1) Use Greek prefixes
to indicate
subscripts
2) second element –ide
ending
H + Nonmetal(s)
Name as acids
* Treat NH4+ as a metal when
naming compounds
Naming of Acids
• If anion does not contain oxygen:
– Start with Hydro– Add –ic to the end
– Ex: HCl: Cl- is chloride, so the acid is
Hydrochloric acid
• If anion contains oxygen:
– Look at the ending
– If –ite, use anion root and -ous
– Ex: HNO2: NO2- is nitrite, so the acid
is Nitrous acid
– If –ate, use anion root and -ic
– Ex: H2SO4: SO42- is sulfate, so the
acid is Sulfuric acid
Nomenclature Practice
Name the following compounds:

Ba(OH)2

NaC2H3O2

Fe3(PO4)2

CaS

MgSO4

K2SO3

P2O5

N2 O

SO3

LiF
Monoatomic Cations
Metal atoms can lose valence
electrons and become positively
charged cations.
Naming Cations: The parent atom
gets the word “ion”.
Na+  “sodium ion”
Al3+  “aluminum ion”
This rule applies for metals that
usually form one ion.
Metals That Form Multiple
Ions
If Metal Forms More than One
Cation:
The parent metal gets the charge
in Roman numerals in parentheses
and followed by the word “ion”.
Fe2+ is the iron(II) ion, ferrous
(old name)
Fe3+ is the iron(III) ion, ferric (old
name)
This is called the Stock system of
naming cations.
Monoatomic Anions
Nonmetals can gain valence
electrons and become negatively
charged anions.
Monoatomic anions are named by
dropping the end of the element
name and adding the suffix –ide.
 Br-  “bromide ion”
O2-  “oxide ion”
N3-  “nitride ion”
Predicting Cation Formulas
Group IA/I metals always form +1
ions and Group IIA/I ions always
form +2 ions.
Group IIIA/13 metals are
predicted to form 3+ ions.
Not all metal ion charges are
predictable.
Tin and lead in Group IVA/14
form both +2 and +4 ions.
Most transition metals form +2
ions from the loss of their 2 selectrons.
Metals and Their Cation
Charges
Predicting Anion Charges
Nonmetals gain electrons to form
anions Group VIIA/17 atoms gain 1
electron to form -1 ions:
F-, Cl-, Br-, and I-
Group VIA/16 atoms gain 2 electrons
to form -2 ions:
O2-, S2-, Se2-, and Te2-.
Group VA/15 atoms gain 3 electrons
to form -3 ions:
N3-, P3-, and As3-.
Polyatomic Anions
Oxyanions:
Polyatomic anions containing one
or more elements combined with
oxygen are called oxyanions.
Most oxyanions have names that
end in the suffix -ate.
SO42-  “sulfate ion”
NO3-  “ nitrate ion”
Naming Oxyanions
Some oxyanions end in the suffix ite.
NO2-  “nitrite ion”
SO32-  “sulfite ion”
The oxyanions that end in -ite each
have one less oxygen than the
oxyanions (compared to the
oxyanions ending in –ate, sulfate
SO42- and nitrate NO3-).
Writing Ionic Formulas
Ionic compound: Composed of
positive and negative ions.
Formula unit shows an ionic
compound.
A formula unit is neutral, so the
total positive charge must equal
the total negative charge in the
formula unit.
When writing chemical formulas,
the cation (metal) goes first and
the anion (nonmetal) goes second.
Formulas of Ionic
Compounds
• If the charges of the ions are the
same, formula unit contains one of
each ion.
Na+ and Cl- form NaCl.
Mg2+ and S2- form MgS.
• If the charges are not equal,
balance the positive and negative
charges.
Ca2+ and Cl- form CaCl2.
Na+ and O2- form Na2O.
Formulas with Polyatomic Ions
Follow the same rules as binary
ionic compounds; if the charges
are equal, the formula has one of
each ion.
Mg2+ and SO42- combine to form
MgSO4
K+ and ClO3- combine to form
KClO3
If the charges are not equal, the
total charge must equal zero. If
you have more than one
polyatomic ion, it is placed in
parentheses.
3+
2-
Naming Binary Ionic
Compounds
Combine the cation and anion
name (drop “ion”) in the
following order :
first cation and second anion.
Example:
MgO is composed of one
magnesium ion and one oxide
ion
The name is magnesium oxide.
Cont’d…Naming Binary Ionic
Compounds
Question: What is the name of
cinnabar, HgS?
Hg2+ is the mercury(II) ion and
S2- is the sulfide ion,
The name is mercury(II) sulfide.
Naming Ternary Ionic
Compounds
Name ternary ionic compounds like
binary ionic compounds: the cation
name followed by the anion name.
Example: K2CO3 is named potassium
carbonate.
If metal can have more than one
oxidation state, determine the charge
on the metal.
Example: Co(ClO3)3 is composed of
cobalt(III) and chlorate ions.
cobalt(III) chlorate
Binary Molecular
Compounds
They are composed of two
nonmetal elements. A molecule is
the simplest representation of a
binary molecular compound.
IUPAC has set the following order,
according to increasing
electronegativity, for writing
elements in a binary molecular
compound:
– C, P, N, H, S, I, Br, Cl, O, F
Naming Binary Molecular
Compounds
• The first element in the compound
is named first and the second
element has the suffix -ide.
• The number of atoms of each
element must be indicated by
Greek
prefixes.
Prefix
Number Indicating
MonoDiTriTetraPentaHexaHeptaOcta
1
2
3
4
5
6
7
8
Cont’d…Names of Binary
Molecular Compounds
Example:
What is the name of the molecular
compound P4S3?
– 4 P atoms  tetra– 3 S atoms  tri– P4S3 is tetraphosphorous trisulfide.
What is the name for Br3O8?
– tribromine octaoxide.
Exceptions
Exception to the use of the Greek
prefixes when naming binary
molecular compounds.
If only one atom exists in the first
element “mono-” is not used. The
prefix mono- is always used for the
second element.
– CO is carbon monoxide
– IF6 is iodine hexafluoride
Binary Acids
 A binary acid is an aqueous solution of
a compound containing hydrogen and a
nonmetal.
The formula of an acid always begins
with H:
– HF (aq)
 Binary acids are named using the prefix
hydro- before the element and adding
the suffix “-ic acid”.
– HF (aq) is hydrofluoric acid
– H2S (aq) is hydrosulfuric acid
Ternary Oxyacids
Ternary oxyacids are aqueous solution of
a compound containing hydrogen and
an oxyanion.
 If acid is derived from an oxyanion
ending in -ate, suffix is changed to “-ic
acid”.
HNO3 (aq) is nitric acid (from NO3-,
nitrate ion)
 If acid is derived from an oxyanion
ending in -ite, suffix is changed to “ous acid”.
HNO2 (aq) is nitrous acid (from NO2-,
nitrite ion)
Lewis Structure for SO3
1. Count the total number of valence
electrons: each oxygen has 6 and
sulfur has 6 for a total of 24 electrons
[3(6) + 6 = 24 e-]. This gives us 12
electron pairs.
2. Place 4 electron pairs around the
central sulfur atom and attach
the three oxygens. We started
with 12 electron pairs and have 8
left.
Cont’d…Lewis Structure for
SO3
3. Place the remaining electron pairs around
the oxygen atoms to complete each octet.
4. One of the oxygens does not have an
octet, so move a nonbonding pair from
the sulfur to provide 2 pairs between the
sulfur and the oxygen.
Electronegativity
•
Electronegativity increases from
left to right in a period.
•
Electronegativity increases from
bottom to top in a group.