2.1 Classifying Matter
Each piece of your clothing has
a label that recommends
cleaning methods. A 100%cotton shirt may need to be
ironed after washing. A cotton
and polyester blend fabric may
come out of the dryer wrinkle
free. There is no cleaning
process that works for all
materials.
2.1 Classifying Matter
Pure Substances
A pure substance is matter that always has exactly
the same ___________________________.
• Table salt and table sugar are two
examples of pure substances.
• Substances can be classified into two
categories—elements and compounds.
Every sample of a given substance has the same
properties because a substance has a fixed,
______________composition.
2.1 Classifying Matter
Elements
An element is a substance that_________be broken
down into simpler substances.
• An element has a fixed composition because it
contains only one type of ___________.
• No two elements contain the same type of atom.
Examples of Elements
• Solids at room temperature: Most soft drink cans are made
from aluminum. Carbon is the main element in the marks you
make with a pencil.
• Oxygen and nitrogen are the main gases in you breathe.
• Two elements are liquids at room temperature–bromine and
mercury.
2.1 Classifying Matter
Symbols for Elements
•
Chemists use symbols of one or two_________to represent
elements.
• The first letter is always_____________. If there is a second
letter, it is not capitalized.
• Symbols allow scientists who speak different languages to
communicate without _________________.
• C represents carbon.
• Al represents aluminum.
• Au represents gold. (The Latin name is aurum.)
Gold
Aluminum
Carbon
Iodine
2.1 Classifying Matter
Compounds
A compound is a substance that is made from two
or more simpler substances and __________broken
down into those simpler substances.
• A compound always contains two or more
elements joined in a fixed proportion.
• The properties of a compound____from those of
the substances from which it is made.
• Water: Oxygen and hydrogen are gases at room
temperature, but water is a liquid.
2.1 Classifying Matter
Compounds
Silicon dioxide is a compound found in most light-colored grains
of sand and in crystals of quartz. It is a colorless, transparent
solid. Yet, silicon dioxide is made from a colorless gas (oxygen)
and a gray solid (silicon). In silicon dioxide, there are always
two oxygen atoms for each silicon atom.
Oxygen
Silicon
Silicon dioxide
2.1 Classifying Matter
Mixtures
If you make salsa, a recipe can guide you. You can
use exactly the amounts in the recipe, or you can
adjust the ingredients to your own taste. Salsa is a
mixture. Each batch may be slightly different.
2.1 Classifying Matter
Mixtures
The properties of a mixture can vary because the
composition of a mixture is not __________.
• Mixtures can_______some of the properties of their
individual substances.
• The properties of a mixture are less constant than
the properties of a substance.
2.1 Classifying Matter
Mixtures
Mixtures can be classified by how well the parts of the
mixture are distributed throughout the mixture.
Heterogeneous Mixtures
In a heterogeneous mixture, the parts of the mixture
are noticeably__________________from one another.
Homogeneous Mixtures
In a homogeneous mixture, the substances are so
evenly distributed that it is difficult to___________one
substance in the mixture from another.
2.1 Classifying Matter
Mixtures
•
The sand is a
heterogeneous mixture of
different kinds of grains.
•
The spoon is
stainless steel, a
homogeneous mixture of
iron, chromium, and nickel.
•
The_________of the
particles in a mixture has
an effect on the properties
of the mixture.
2.1 Classifying Matter
Solutions, Suspensions, and Colloids
Based on the size of its largest particles, a mixture
can be classified as a solution, a suspension, or a
colloid.
Solutions
When substances________and form a homogeneous
mixture, the mixture that forms is called a solution.
Suspensions
A suspension is a heterogeneous mixture that
separates into___________over time.
2.1 Classifying Matter
Solutions, Suspensions, and Colloids
Colloids
A colloid contains some particles that are
____________in size between the small particles in a
solution and the larger particles in a suspension.
• Like solutions, colloids do not separate into
layers.
• You cannot use a_____to separate the parts of a
colloid.
2.1 Classifying Matter
Solutions, Suspensions, and Colloids
These liquids represent three categories of
mixtures.
• Windshield wiper fluid is a solution.
• Muddy water collected from a swamp is a
suspension.
• Milk is a colloid.