Chapter 2
Matter and Change
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Section 2.1
Matter
 OBJECTIVES:
–Identify the characteristics of
matter and substances.
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Section 2.1
Matter
 OBJECTIVES:
–Differentiate among the three
states of matter.
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Section 2.1
Matter
 OBJECTIVES:
–Define physical property, and list
several common physical
properties of substances.
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What is Matter?
 Matter
is anything that takes up
space and has mass.
 Mass- amount of material or “stuff” in
an object
 Weight is due to gravity, and
changes from location to location;
mass is always constant.
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Types of Matter
 Substance-
a particular kind of matter
- pure; is uniform (all the same) and
has a definite composition (examples
are elements & compounds)
–water; gold; lemonade?
 Mixture- more than one kind of
matter; has a variable composition
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Properties
 Words
that describe matter (adjectives)
 Physical Properties- a property that can
be observed and measured without
changing the composition.
 Examples- color, hardness, m.p., b.p.
 Chemical Properties- a property that
can only be observed by changing the
composition of the material.
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States of matter
 Solid-
matter that can not flow (definite
shape) and has definite volume.
 Liquid- definite volume but takes the
shape of its container (flows).
 Gas- a substance without definite
volume or shape and can flow.
 Vapor- a substance that is currently a
gas, but normally is a liquid or solid at
room temperature. (water vapor?)
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States of Matter
Definite Definite Temp.
ComVolume? Shape? increase pressible?
Solid
Liquid
Gas
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YES
YES
NO
YES
Small
Expans.
NO
NO
Small
Expans.
NO
NO
Large
Expans.
YES
Condense
Freeze
Evaporate
Melt
Solid
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Liquid
Gas
Physical Changes
 A change
that changes appearances,
without changing the composition.
 Ex. Boil, melt, cut, bend, split, crack
 Boiled water is still water.
 Chemical changes - a change where
a new form of matter is formed.
 Ex. Rust, burn, decompose, ferment
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Section 2.2
Mixtures
 OBJECTIVES:
–Categorize a sample of matter as
a substance or a mixture.
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Section 2.2
Mixtures
 OBJECTIVES:
–Distinguish between homogeneous
and heterogeneous samples of
matter.
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Mixtures
 Physical
blend of at least two
substances; variable composition
 Heterogeneous- mixture is not uniform
in composition
 Chocolate chip cookie, gravel, soil.
 Homogeneous- same composition
throughout; called “solutions”
 Kool-aid, air, salt water
 Every part keeps it’s own properties.
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Solutions
 Homogeneous
mixture
 Mixed molecule by molecule
 Can occur between any state of
matter
–Table 2.3, page 33
–gas in gas; liquid in gas; gas in
liquid; solid in liquid; solid in solid
(alloys), etc.
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Solutions
 Like
all mixtures, they keep the
properties of the components.
 Some can be separated easily by
physical means: rocks and marbles,
iron filings and sulfur
 Other methods: distillation- takes
advantage of different boiling points
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Section 2.3
Elements and Compounds
 OBJECTIVES:
–Explain the differences between
an element and a compound.
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Section 2.3
Elements and Compounds
 OBJECTIVES:
–Identify the chemical symbols of
common elements, and name
common elements given their
symbols.
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 Elements-
Substances
simplest kind of matter
 cannot be broken down any simpler
 all one kind of atom.
 Compounds are substances that can be
broken down only by chemical methods
 When broken down, the pieces have
completely different properties than the
original compound.
 Made of two or more atoms, chemically
combined (not physical blend!)
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Compound or Mixture
Compound
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Mixture
Made of one kind
of material
Made of more than
one kind of material
Made by a
chemical change
Made by a
physical change
Definite
composition
Variable
composition
Which is it?
Mixture
Element
Compound
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Chemical Symbols & Formulas
 Currently,
there are 115 elements
 Each has a 1 or two letter symbol
 First letter always capitalized; the
second never; chemical “shorthand”
 Don’t need to memorize all of them;
know Table A.3 inside back cover
 Some from Latin or other languages;
note Table 2.4, page 40
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Section 2.4
Chemical Reactions
 OBJECTIVES:
–Differentiate between physical
and chemical changes in matter.
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Section 2.4
Chemical Reactions
 OBJECTIVES:
–Apply the Law of Conservation of
Mass.
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Chemical Reactions
 When
one or more substances are
changed into new substances.
 Reactants- stuff you start with
 Products- What you make
 ability to undergo chemical reaction
is called a chemical property
 products have NEW PROPERTIES
 Arrow from reactants to products
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Indications of a chemical reaction:
 Energy
absorbed or released
(temperature changes hotter or colder)
 Color change
 Gas production (bubbling, fizzing, or
odor change)
 formation of a precipitate- a solid that
separates from solution (won’t dissolve)
 Irreversibility- not easily reversed
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Law of Conservation of Mass
 Mass
can not be created or
destroyed in ordinary (not nuclear)
chemical reactions or physical
change
 All the mass can be accounted for.
–Burning of wood results in
products that appear to have less
mass as ash; where is the rest?
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Chapter 2 Matter and Change