Chemistry Section V Building With Matter (pg. 124-143)
Classifying Substances.
 Many of the substances we know about can be sorted into general
categories according to their properties, such as solubility (the ability
to dissolve) melting point (the temperature at which a substance
melts) and conductivity (the ability to conduct electricity).
o Some substances, like sugar, sodium chloride, and ammonium
sulfate, dissolve in water to make an aqueous solution (a
term we learned a few weeks ago). Gold, however, does not
dissolve in water (but aqua regia, which we learned about in
our first unit, can dissolve gold).
 A substance that dissolves in water is said to be soluble in
water, and one that does not dissolve is said to be
Oil and
insoluble. Therefore sodium chloride is soluble in
water are
water, while gold is insoluble in water.
insoluble.
o The property of conductivity is related to a substance’s
ability to conduct electricity. Electrical conductivity
Or battery
requires the movement of ions or electrons.
 Copper wire is an excellent conductor; the human
body can also act as a conductor. Rubber is a
poor conductor.
 Electrical conductivity can be tested by setting up a simple electrical
circuit—if the substance being tested is part of the circuit, it will either lead to
the flow or blockage of an electrical current. This is easy to test if a light
bulb is also part of the circuit; if the bulb lights up, the substance conducts
electricity
Properties
soluble in water/
conduct electricity/
high melting point
soluble in water/
do not conduct
electricity/
low melting point
insoluble in water/
conduct
electricity/
high melting point
insoluble in water/
do not conduct
electricity/
high melting point
Examples
Sodium chloride,
copper sulfate
sucrose C12H22O11,
(“table sugar”); carbon
dioxide, CO2
Gold, copper,
aluminum
sand/glass (SiO2);
diamonds (C)
Types of
Atoms
ionic compounds
(a metal and a
nonmetal, or
polyatomic ions) in
aqueous solution
nonmetals; often C, H,
and O
metals
nonmetals
Type of
Bond
Ionic
Molecular covalent
Metallic
Network covalent
Electrons
are…
Transferred
Shared between
atoms in a molecule
Free-flowing “sea
of electrons”
Shared
throughout
substance
Description
Brittle solids
Often liquids or gases;
sometimes solids
Bendable,
malleable solids
Extremely hard
solids
Packet 3 Example 1: Predicting Properties
Predict whether the following substances will dissolve in water, and whether they will conduct
electricity.
Lead
soluble / insoluble
conduct / not conduct
Potassium bromide
soluble / insoluble
conduct / not conduct
Bonding
 Chemists call the attraction that holds atoms together a
chemical bond. Several types of bonds exist, and they all
involve electrons in some way.
Carbon dioxide exists
as separate CO2
molecules; silicon
dioxide exists as a
network of silicon
and oxygen.

We’ve seen that most substances can be divided into four
categories based on their physical properties. These
categories can be explained by different models of bonding. You can see these in the
table on the previous page.

Some properties are directly related to the type of bonds the atoms in the substances
have. Therefore, it is possible to match the bonding with the physical properties observed
in different substances.
o Conduction requires the movement of charged particles.
 Ionic substances in aqueous solution contain free-moving cations and
anions, so they conduct electricity.
 Metallic substances conduct electricity because their valence electrons are
free to move within the solid.
 Network covalent substances and molecular covalent substances do not
contain ions or transfer electrons, so they do not conduct electricity.
o Melting point depends on the attractive forces between the particles.
 The higher the melting point, the stronger the attractive forces.
Packet 3 Example 2: Identifying Types of Bonds
Determine the type of bond in each of the following substances. Then decide the physical
properties each substance would have.
Substance
Type of Bond Soluble in
Conducts
Electrons
Description
water?
electricity?
are…
Magnesium
chloride,
MgCl2
Rubbing
alcohol,
C3H8O
Electroplating Metals
 Most metals are dug out of the ground as ionic compounds (ores); in other words, they
cannot be found in nature in their pure forms. Through the ages, people have struggled to
extract the pure metals from these ores; some are easier to purify than others.
o Despite being the third most common element in Earth’s crust, aluminum was
one of the most difficult metals for scientists to isolate. It was first purified in 1827
by a German chemist named Friedrich Wöhler. Processing aluminum was still
difficult and inefficient, making it more expensive per ounce than gold for quite
some time. Napoleon III famously let only his favorite guests use his aluminum
cutlery, while the rest had to use gold. The Washington Monument was also
capped with aluminum which (at the time) was as expensive as silver. It was not
until the advent of electrolysis (running an electric current through aluminum ore),
that the isolation of aluminum became more efficient, therefore dropping the price of
aluminum.

Electricity can be used to extract metal from compounds by
“giving” electrons back to metal ions, which converts them to
neutral metal atoms. This process is called electroplating.
o Ex. Copper metal can be extracted from a copper sulfate
solution by running an electrical current through the
solution.