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Chapter 2 Atoms and Elements
2.1Classification of Matter
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
A pure substance is classified as Matter with a specific composition.
An element when composed of one type of atom.
A compound when composed of two or more elements chemically combined in a definite ratio.
Pure Substances
Elements
Elements are Pure substances that
contain atoms of only one type.
Copper Cu
Lead Pb
Aluminum Al Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
Compounds
Compounds Contain two or more
elements bonded together in a definite ratio.
Salt (NaCl)
Table sugar (C12H22O11)
Water (H2O)
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
Elements in a Compound
“Table salt” is a compound that contains the elements sodium and chlorine.
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
Reaction
Identify each of the following as a pure substance or a mixture.
A. pasta and tomato sauce
B. aluminum foil
C. helium
D. air
Learning Check
Identify each of the following as a pure substance or a mixture.
A. pasta and tomato sauce mixture
B. aluminum foil pure substance
C. helium pure substance
D. air mixture
Solution
Mixtures
A mixture is matter that consists of Two or more substances that are physically
mixed, not chemically combined. Two or more substances in different proportions. Substances that can be separated by physical
methods.
Homogeneous Mixtures
In a homogeneous mixture,
The composition is uniform throughout.
The different parts of the mixture are not visible.
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
Heterogeneous Mixtures
In a heterogeneous mixture,
The composition is not uniform, it varies from one part of the mixture to another.
The different parts of the mixture are visible.
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
Identify each of the following as a homogeneous orheterogeneous mixture:
A. hot fudge sundae
B. shampoo
C. sugar water
D. peach pie
Learning Check
Identify each of the following as a homogeneous orheterogeneous mixture:
A. hot fudge sundae heterogeneous mixture
B. shampoo homogeneous mixture
C. sugar water homogeneous mixture
D. peach pie heterogeneous mixture
Solution
Physical Separation of A Mixture
The physical separation of a mixture Involves only physical changes. Occurs when is pasta and water are separated
with a strainer.
Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings
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