Chapter 5 Types of
Compounds
5.1 Ionic Compounds
5.2 Molecular Substances
5.1 Ionic Compounds - Objectives
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Apply ionic charge to writing formulas for
ionic compounds
Apply formulas to name ionic compounds
Interpret the information in a chemical
formula
Formula and Names of Ionic
Compounds
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Ionic compounds are composed of ions
bound by ionic bonds usually a metal and
a nonmetal
Ionic bonds are strong attractive forces
Ionic compounds are usually solids at
room temperature
Many are crystalline
Difficult to melt  high melting points
When melted or in solutions they conduct
electricity
Binary Ionic Compounds
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Binary compound- composed of two
elements
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Binary ionic compounds- composed of two
different ions
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NaCl
KI
CaF2
Ions
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Positively charged = cation
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When naming the name stays the same
Calcium ion
 Sodium ion
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Negatively charged = anion
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When naming the name is changed
Ending becomes –ide
Chloride ion
 Sulfide ion
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Naming Binary Ionic Compounds
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Always write the cation first followed by
the anion.
Make sure the anion ending is modified to
–ide.
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Na+ + Cl-  Sodium Chloride
K+ + I-  Potassium Iodide
Writing Binary Ionic Compound
Formulas
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Compounds are always neutral
Net ionic charge must always be zero
Use subscripts to indicate when more than one
ion of an element is present
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When only one ion is present, no subscript is needed
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NaCl
When more than one is present subscripts are need
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CaF2  1 Calcium ion and 2 fluoride ions
Binary Ionic Compounds
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Always written in the smallest whole
number ratio – Formula Unit
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Example Calcium Fluoride
Predicting Charges on Ions
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Oxidation Number- the charge on the ion
Metals always lose electrons when they
form ions
Nonmetals always gain electrons when
they form ions
Periodic table can be used to predict the
oxidation number (charge of ion) of some
elements
Table 5.1 Ionic Charges of
Representative Elements
Group Number
Metals
1
2
13
Nonmetals
15
16
17
Oxidation Number
1+
2+
3+
321-
Examples
Li+, Na+, K+
Mg2+, Ca2+
B3+, Al3+
N3-, P3O2-, S2F-, Cl-, Br-, I-
Let’s Try It!
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Write the formula for an ionic compound
containing sodium and sulfur.
What is the name of the compound?
Write a formula for each of the
following compounds
1.
Lithium oxide
2.
Calcium bromide
3.
Sodium oxide
4.
Aluminum sulfide
Write the formula & name for the
compound formed from each of the
following pairs of elements.
1.
Barium and oxygen
2.
Strontium and iodine
3.
Lithium and chlorine
4.
Radium and chlorine
5.1 Ionic Compounds
Compounds Containing Polyatomic
Ions
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Polyatomic Ions-an ion that has two or
more different elements
Group of atoms are covalently bonded
together when the atoms share electrons
The individual atoms do not have a
charge, but the group as a whole has an
overall charge
Polyatomic Ions
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Ionic compounds may contain positive
metal ions bonded to negative polyatomic
ions or negative nonmetal ions bonded to
positive polyatomic ions
Writing formulas using Polyatomic
Ions
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Treat the polyatomic ion as one unit or a
single ion
Write the cation ion first followed by the
anion
When more than one polyatomic ion is
needed to make the net charge zero you
place it in parentheses and then add the
subscript.
Common Polyatomic Ions
1- charge
2- charge
3- charge
Formula
Name
Formula
Name
Formula
Name
H2PO4C2H3O2HSO3HSO4HCO3NO2NO3CNOHMnO4ClOClO2ClO3ClO4-
Dihydrogen phosphate
Acetate
Hydrogen sulfite
Hydrogen sulfate
Hydrogen carbonate
Nitrite
Nitrate
Cyanide
Hydroxide
Permanganate
Hypochlorite
Chlorite
Chlorate
Perchlorate
HPO42C2O42SO32SO42CO32CrO42Cr2O72SiO32-
Hydrogen phosphate
PO43PO33-
Phosphate
Phosphite
Oxalate
Sulfite
Sulfate
Carbonate
Chromate
Dichromate
Silicate
1+ charge
Formula
Name
NH4+
H3O+
Ammonium
Hydronium
Naming Polyatomic Ions
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Follows the same rules as naming binary
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Name the cation first and then the anion
You do not change the ending of the anion for
polyatomic ions
-ite indicates one less oxygen atom than -ate
-ate indicates one more oxygen atom than –ite
Does not tell you the number of oxygen atoms
in the ion
Let’s Try It!
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Write the formula for the compounds
made from each of the following ions.
1.
2.
3.
4.
Ammonium and sulfite ions
Calcium and hydrogen phosphate ions
Ammonium and dichromate ions
Barium and nitrate ions
Let’s Try It!
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Write the formula for each of the
following compounds.
1.
2.
3.
4.
Sodium phosphate
Magnesium hydroxide
Ammonium phosphate
Potassium dichromate
Compounds of Transition Elements
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Transition elements are groups 3 through
12 in the periodic table
Form positive ions, but they form more
than one type of positive ions
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Copper forms two ions one with a +1 charge
and one with a +2 charge
The way they are distinguished is with roman
numeral. Copper (I) and Copper (II)
Names of Common Ions of Selected Transition Elements
Element
Ion
Chemical Name
Chromium
Cr2+
Cr3+
Cr6+
Chromium (II)
Chromium (III)
Chromium (VI)
Cobalt
Co2+
Co3+
Cobalt (II)
Cobalt (III)
Copper
Cu+
Cu2+
Copper (I)
Copper (II)
Gold
Au+
Au3+
Gold (I)
Gold (III)
Iron
Fe2+
Fe3+
Iron (II)
Iron (III)
Manganese
Mn2+
Mn3+
Mn7+
Manganese (II)
Manganese (III)
Manganese (VII)
Mercury
Hg+
Hg2+
Mercury (I)
Mercury (II)
Nickel
Ni2+
Ni3+
Ni4+
Nickel (II)
Nickel (III)
Nickel (IV)
Let’s Try It!
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Write the formula for the compounds
made from each of the following pairs of
ions.
1.
2.
3.
4.
Copper (I) and sulfite
Tin (IV) and fluoride
Gold (III) and cyanide
Lead (II) and Sulfide
Let’s Try It!
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Write the names of the following
compounds.
1.
2.
3.
4.
Pb(NO3)2
Mn2O3
Ni(C2H3O2)2
HgF2
Hydrates
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Many ionic compounds are prepared by
crystallization from a water solution, and
water molecules become a part of the
crystal.
Hydrates- a compound in which there is a
specific ratio of water to ionic compound.
In hydrate, the water molecules are
chemically bonded to the ionic compound
Hygroscopic
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Hygroscopic- a substance that absorbs water
molecules from the air to become a hydrate.
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Sodium Carbonate
Some substances are so hygroscopic that they
take up enough water from the air to dissolve
completely and form a liquid solution. These
compounds are called deliquescent.
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Sodium Hydroxide
Writing Formulas for Hydrates
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When writing a formula for a hydrate you
place a dot in the formula between the
ionic compound and the water.
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CaSO4 · 2H2O
What this means is for every one calcium
sulfate there are two water molecules in the
hydrate.
Naming Hydrates
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You use the regular name for the compound
followed by the word hydrate, to which a prefix
is added.
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1
2
3
4
=
=
=
=
monoditritetra-
Exp.: CaSO4 · 2H2O  Calcium sulfate dihydrate
Anhydrous
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Anhydrous – a compound in which all the water
has been removed, usually by heating
In some cases the anhydrous compound may be
a different color than the hydrate.
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Copper (II) sulfate pentahydrate is blue compound
when it is heated to remove the water and become
anhydrous it turns white, this compound is Copper
(II) sulfate anhydrous
Homework
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P. 184-185 #1-5, 7, 8