Chapter 17 - Seymour ISD
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Transcript Chapter 17 - Seymour ISD
Section 1: Composition of Matter
Substance—either an element or a compound
When all the atoms in a substance are alike, the
substance is an element.
A compound is a substance with two or more elements
combined in a fixed proportion.
Two or more substances that can be easily separated by physical
means form a mixture.
Heterogeneous mixture—mixture of different and easily distinguishable
materials
Colloid—heterogeneous mixture with larger particles that never settle;
colloids scatter light in the Tyndall effect
A heterogeneous mixture containing a liquid in which visible particles settle
is called a suspension.
Homogeneous mixture—contains two or more gaseous, liquid, or solid
substances blended evenly; also called a solution
Section 2: Properties of Matter
Physical property—
characteristics of a material
which can be observed
without changing the
identity of the substances in
the material; examples
include color, shape, size,
melting point, and boiling
point
Appearance—physical
description of a
substance
Behavior—how a
substance acts; for
example, magnetism,
viscosity, ductility
Physical properties such
as size and magnetism
can be used to separate
mixtures.
Physical change—change in a substance’s
size, shape, or state of matter
Substance does not change identity when it
undergoes a physical change
Distillation is a process for separating a mixture
by evaporating a liquid and condensing its
vapor.
Chemical property—characteristics of a substance
indicating that it can change chemically; for example,
flammability or light sensitivity of a substance
When one substance changes to another
substance, a chemical change has occurred.
Some chemical changes are indicated by
temperature change, smell, or bubble
formation.
Other chemical changes occur very slowly such
as the formation of rust.
Chemical changes can be used to separate
substances such as metals from their ores.
Weathering of Earth’s surface involves both
physical and chemical changes.
Physical—big rocks split into smaller ones;
streams carry rock particles from one location
to another
Chemical—Chemical changes can occur in rocks
when calcium carbonate in limestone changes
to calcium hydrogen carbonate due to acid rain.
Rock Cycle
Law of Conservation of
Mass—Mass of all
substances present
before a chemical change
equals the mass of all
substances after the
change.
1. Which element makes up
greater than 50 percent of the
elements dissolved in seawater?
A Sodium
B Sulfur
C Magnesium
D Chlorine
2. Which element is found
dissolved in seawater about
twice as much as magnesium?
F Calcium
G Sodium
H Sulfur
J Potassium
3. Which of the following is a
compound?
A Ca
B MgS
C Cl2
D Na
Classify the following as a mixture or pure
substance, and atom, molecule, or compound.
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.