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DMAE Chemistry
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Elements and Compounds
Introduction
Most of the materials you have used so far in this course were mixtures. If you
could take them apart physically, you would find that they are made of two or more
other substances. Some are compounds, which are also made of two or more
substances, but they cannot be taken apart physically—they can only be separated
using chemical reactions. When you take something apart completely so that it
cannot be separated further either chemically or physically, you have an element.
In ancient Greece, the famous philosopher Aristotle stated that there were four
“elements”: Earth, Wing, Fire, and Water. By the late 18th Century (1700s),
scientists knew that these weren’t really elements, and had identified about 10 – 20
elements, such as gold, silver, copper, and iron. Using early electricity experiments,
they separated water into two invisible gases—oxygen and hydrogen (whose name
means “coming from water.”)
During the early 19th Century (1800s), chemistry really began to develop into a
“mature” science. Chemists used electricity, heat, and acids to separate rocks and
minerals into their compounds and elements. By the middle of the 19 th Century,
about 70 elements were known. Later in this course, you’ll learn more about how
two chemists, Dmitri Mendeleev and Henry Moseley, organized these into a chart
called the Periodic Table of the Elements. You’ll also learn how people later
discovered all 92 natural elements and have created more than 23 synthetic
elements in laboratories.
In this activity, you will have the opportunity to examine representative samples
of minerals and rocks to learn more about elements and compounds. Minerals are
naturally-occurring solids that combine to make rocks, which are mostly mixtures.
Most of these are inorganic substances. But you will also look at some examples of
organic materials to identify the compounds and elements that compose them.
DMHS Chemistry
Elements and Compounds, p. 2
Procedure
1) Examine the samples provided and complete the Observation Table on the
other sheet. You should use your textbook, “Properties of Common Minerals
and Other Materials” (below), and other resources to learn as much as
possible about the materials.
2) There are three blank rows at the end. Find out about three other elements or
compounds, and complete the cells in these rows
When you finish attach the sheet to these guide sheets.
3) Answer the questions at the end of the information table.
“Properties of Common Minerals and Other Materials”
Name
Composition
Characteristics
Uses
Aluminum
Al
silvery metal, low
buildings, foil,
density
many others
Biotite mica
K(Mg,Fe)3AlSi3O10(OH)2
dark thin sheets
electrical insulator
Calcite
CaCO3
rhombic crystals
cement, prisms
or massive
Candle wax
C17H35O2
soft, easily
flames
Copper
Cu
brassy-yellow
electric wires,
many others
Feldspar
KAlSi3O8
pinkish mineral
common in many
rocks, ceramics
Graphite
C
lead gray
pencils
Hematite
Fe2O3
reddish-brown
ore of iron
Magnetite
Fe3O4
black or silvery,
ore of iron
dense
Malachite
Cu2(CO3)(OH)2
green
ore of copper,
jewelry
Marble (a rock)
Muscovite mica
CaCO3
KAl3Si3O10(OH)2
white or streaked
buildings and
rock
other structures
light thin sheets
electrical insulator
DMHS Chemistry
Quartz
Elements and Compounds, p. 3
SiO2
colorless or
most common
variable
mineral
ore of iron
Pyrite
FeS2
brassy-yellow
Silicon
Si
shiny dark solid
Sugar
C12H22O11
white, crystalline
major body
energy source
Sulfur
S
yellow
“brimstone”
Zinc
Zn
silvery rough solid
important metal
Zincite
ZnO
orange-yellow
ore of zinc
Questions
1. Which of these substances are elements?
2. Which of these substances are compounds made of two elements?
3. Which of these substances are compounds made of three or more elements?
4. Which two are organic?
5. What produces the various colors in quartz?
6. Name any five substances that are gases, and tell if it is an element or
compound.
7. The only liquid you examined is water. Use your references to find the names
of the two elements that are liquid at room temperatures.
DMHS Chemistry
Elements and Compounds, p. 4
Observation Table
Name
Sulfur
Copper
Silicon
Aluminum
Zinc
Quartz
Feldspar
Biotite mica
Muscovite mica
Calcite
Marble
Graphite
Hematite
Magnetite
Malachite
Zincite
Pyrite
sample
element(s) that
characteristics and/or other
number
compose it
comments
DMHS Chemistry
Elements and Compounds, p. 5
Observation Table, cont’d.
Name
Sugar
Candle wax
Water
sample
element(s) that
characteristics and/or other
number
compose it
comments