Section V: Building With Matter
Lesson 25 You Light Up My Life
Lesson 26 Electron Glue
Lesson 27 Electrons on the Move
Lesson 25: You Light Up My Life
Classifying Substances
ChemCatalyst
1. If you were to drop a spoonful of salt, NaCl, into
a glass of water, what would happen?
2. If you were to drop a gold ring into a glass of
water, what would happen?
3. What do you think is different about the atoms
of these two substances? Why do you suppose
the gold atoms don’t break apart?
Key Question
How can substances be sorted into general
categories?
You will be able to:
•
•
•
classify substances into four categories based
on solubility and conductivity
explain the difference between the terms
soluble and insoluble
begin to describe the atomic makeup of
substances based on whether they are soluble
and/or conduct electricity
Prepare for the Lab
Work in pairs.
Wear safety goggles at all times during the lab.
Dissolve: To disperse evenly into another
substance. For example, a solid can dissolve in a
liquid.
Conductivity: A property that describes how well
a substance transmits electricity.
Prepare for the Lab (cont.)
Dissolving and conductivity can be demonstrated
with a powdered sports drink and a light bulb
assembly like the one shown below.
Discussion Notes
Generalizations about substances that do not light
up the bulb:
• Compounds made up of C, H, and O atoms do
not conduct electricity.
• Compounds made up entirely of nonmetals do
not light up the bulb.
• Compounds made up of a combination of
metals and nonmetals do not light up the bulb
when they are in their solid form.
Discussion Notes (cont.)
Generalizations about substances that do light up
the bulb:
• Everything that lights up the bulb has a metal
atom in it.
• Compounds made of metal and nonmetal
atoms, such as salts, light up the bulb when
they are dissolved in water. (The sports drink is
a solution of water, various salts, sugar, and a
dye.)
• Metal solids light up the bulb.
Discussion Notes (cont.)
Solubility and Conductivity
Discussion Notes (cont.)
We can place all the substances tested into one of
the four categories.
Soluble: Describes a substance that is capable of
being dissolved in another substance.
Insoluble: Describes a substance that is incapable
of being dissolved in another substance.
Wrap Up
How can substances be sorted into general
categories?
• Not all substances dissolve in water.
• Not all substances conduct electricity.
• Solid metals and metal–nonmetal compounds
dissolved in water conduct electricity.
Check-in
Predict whether MgSO4(aq), commonly known as
Epsom salts, will conduct electricity. State your
reasoning.
Lesson 26: Electron Glue
Bonding
ChemCatalyst
A gold ring is made up of individual gold atoms.
1. What keeps the atoms together? Why don’t
they break apart from one another?
2. What parts of the atom do you think are
responsible for keeping the atoms together in a
solid?
Key Question
How are atoms connected to one another?
You will be able to:
• define a chemical bond and describe the four
basic types of chemical bonds
• use chemical formulas to sort substances into
bonding categories
• predict the properties of a substance based on
its chemical formula and bonding type
Prepare for the Activity
Work in pairs.
Chemical bond: An attraction between atoms that
holds them together in space.
Prepare for the Activity (cont.)
Four Models of Bonding
Discussion Notes
The different locations of the electrons among
atoms account for many different properties of
substances.
Discussion Notes (cont.)
Ionic bonding: A type of chemical bonding that is
the result of transfer of electrons from one atom to
another.
Covalent bonding: A type of chemical bonding in
which one or more pairs of valence electrons are
shared between the atoms. Covalent bonding can
be molecular covalent or network covalent.
Discussion Notes (cont.)
Metallic bond: A bond between metal atoms in
which the valence electrons are free to move
throughout the substance.
Molecule: A group of atoms covalently bonded
together.
Discussion Notes (cont.)
The chart created in the previous lesson can now
be labeled with the four types of bonds.
Discussion Notes (cont.)
Bonding also relates to the type of atom in the
substance—metal or nonmetal.
Metal atoms
Metallic
Nonmetal atoms
Network
covalent
Molecular
covalent
Metal and nonmetal atoms
Ionic
Wrap Up
How are atoms connected to one another?
• A chemical bond is an attraction between atoms
involving valence electrons.
• There are four types of bonds: ionic, network
covalent, molecular covalent, and metallic.
• Valence electrons are distributed differently
depending on the type of bond.
Check-in
Imagine that you have a mystery substance that
does not dissolve in water and does conduct
electricity.
1. What type of bonding will you probably find in
your substance? Explain.
2. List one other property of your mystery
substance.
Lesson 27: Electrons on the
Move
Electroplating Metals
ChemCatalyst
1. What is the charge on the
copper ions in this copper
chloride compound?
2. How do you think we
could get solid copper
from a sample of copper
(II) sulfate, CuSO4?
Copper and
chlorine atoms
combine to form
copper (II) chloride.
Key Question
How can you extract an element from a
compound?
You will be able to:
•
•
assemble an electroplating apparatus
explain how to extract elemental metal from an
ionic compound through electroplating
Prepare for the Lab
Work in pairs. Wear safety goggles at all times.
The solution contains acid, which is corrosive.
Before handling the nickel strip, rinse it with
water.
Discussion Notes
It is possible to transform metal cations in solution
into neutral metal atoms, using electricity.
Discussion Notes (cont.)
Aqueous copper (II) sulfate, CuSO4(aq), is really
copper cations, Cu2+, and sulfate anions, SO42–.
Before
connecting to
the battery
Discussion Notes (cont.)
Once the battery is hooked up, one nickel strip has
a positive charge, and the other has a negative
charge.
After connecting
to the battery
Discussion Notes (cont.)
Many elements are found in nature only in
combination with other atoms in compounds.
While you cannot make gold by moving electrons,
you can plate thin layers of gold onto jewelry.
Wrap Up
How can you extract an element from a
compound?
• Atoms are not destroyed when they combine to
form compounds. Matter is conserved.
• Ions are simply atoms or groups of atoms with
charges on them because they either are
missing electrons or have extra electrons.
• Elements can be extracted from ionic
compounds by moving electrons between
atoms.
Check-in
1. What is required to transform CuCl2(aq) into
Cu(s)?
2. What is required to transform CuCl2(aq) into
Au(s)?