Unit 2: Matter and
Change
OBJECTIVES
Students will be able to:
1. define matter
2. describe the states of matter (solid, liquid,
gas)
3. identify the characteristics of of a substance,
element and compound
4. distinguish between physical and chemical
change
5. identify properties of matter (chemical,
physical, intensive, extensive)
6. identify changes in matter that occur
(physical and chemical change)
7. explain the law of conservation of mass
WHAT IS MATTER?
• Matter is anything that takes up space and
has mass
• Matter or not?
– gold
– sound
– sunlight
– air
– water
– heat
– thoughts
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MASS & WEIGHT
• Mass is the measure of the amount of matter
that makes up an object
• Weight is a measure of the force of gravity on an
object
– weight = mass x gravity
– weight varies depending on distance from the earth’s
surface
• Because the value never changes, scientists
use mass, not weight to measure matter
STATES OF MATTER
Shape
Takes the shape of
container
Takes the shape of
container
Definite shape
Volume
Fills volume of container
Definite volume
Definite Volume
Arrangement
of particles
Random, far apart
Random, close
Fixed, close
Attraction
between
particles
Essentially none
Strong
Very strong
GAS vs. VAPOR
• Gases and vapors are similar, but
terms should not be used
interchangeably
– Gas refers to a substance that is naturally
in the gaseous state at room temperature:
hydrogen gas
– Vapor refers to the gaseous state of a
substance that is a solid or a liquid at
room temperature: water vapor
THE PHASES OF WATER
solid
liquid
gas
Matter
Anything that has mass and takes up space
Pure Substance
Matter with an unique
and unchanging
composition
Element
Pure
substance that
chemical
cannot be
change
broken into
more simpler
substances
Mixtures
physical change
Compound
Atoms of two
or more
elements that
are chemically
united in a
fixed
proportion
A combination of 2 or
more pure
substances
Homogeneous
Mixture/Solutio
n
Mixture with a
uniform
composition
Heterogeneo
us
Mixture
Mixture does
not appear to
be the same
throughout
(PURE) SUBSTANCE
• A substance is a form of matter with an unique and
unchanging composition (composition doesn’t
change from sample to sample)
• Examples: Water, salt
• What about salt water?
• All pure substances are either elements or
compounds
ELEMENT
• An element is a substance that cannot be broken
into more simpler substances
• Examples: gold (Au), oxygen (O2)
• To date, there are 118 elements
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COMPOUNDS
• Compounds are substances composed of atoms
of two or more different elements that are
chemically united in a fixed proportion
– Water (H2O), sugar (sucrose, C12H22O11),
ammonia (NH3)
• Compounds can be separated back into its
elements (by chemical means)
– Electrolysis of water:
• 2H2O  2H2 + O2
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PROPERTIES OF MATTER
• Every pure substance has a unique set of
properties
• A property is a characteristic that allows us to
recognize a certain type of matter
Physical properties of water
clear liquid at room
temperature
boils at 100oC
freezes at 0oC
density at 4oC is 1.000 g/cm3
PHYSICAL PROPERTIES
• Physical properties are
those properties that can
be measured without
changing the identity of
the substance:
– color, odor, melting point,
boiling point, density, hardness,
taste
• Physical properties are
either extensive or
intensive
Extensive property Intensive property
•A property that depends
on the amount of a
substance present
•Example: Mass, volume,
length
•value will change when
the amount of substance
changes: 1 mL of water
has a mass of 1 g while
the mass of 1 L has a
mass of 1000 g
•A property that is
independent of the
amount of substance
present
•Example: Density, boiling
point, melting Point
•value will not change
when the amount of
substance changes: The
density of water is always
1.00 g/mL
CHEMICAL PROPERTIES
• Chemical properties describe the way a substance
may change or react to form other substances
– Corrosion, flammability
• The inability of a substance to change is also
a chemical property
– Argon gas is inert
• To observe a chemical property a chemical
change must occur
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PROPERTIES OF COPPER
Physical properties
reddish brown, shiny
good conductor of heat
Chemical properties
Forms a green copper
carbonate compound
when in contact with
moist air
Forms new substances
when combined with
nitric & sulfuric acid
Density = 8.92 g/cm3
Melting point = 1085oC
Boiling Point = 2570oC
Forms deep blue
solution when in
contact with ammonia
CHANGES IN MATTER
• A physical change is a change that
alters the appearance of the substance
drastically but leaves its composition
unchanged:
– bend, grind, split, crush, boil, freeze, melt,
vaporize
Chemical Change (Chemical
Reaction)
• In a chemical change a substance is transformed
into a chemically different substance
– When hydrogen burns in air it reacts with
oxygen to form water
• The new substances formed have different
compositions and different properties
• Terms: Explode, rust, oxidize, corrode, tarnish,
ferment, burn, rot etc.
EVIDENCE OF CHEMICAL CHANGE
Formation of a gas or solid; color change;
energy change; odor
PHYSICAL OR CHEMICAL CHANGE?
• Plants use carbon dioxide and water to
make sugar.
• On a cold day, water vapor in the air
forms frost.
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THE LAW OF CONSERVATION OF MASS
• Mass (matter) is neither created nor
destroyed during a reaction…mass
is conserved:
Massreactants = Massproducts
2HgO  2Hg + O
216 g  200 g + 16 g
reactants  products
PRACTICE PROBLEM
1. In a complete reaction of 22.99 g of
sodium with 35.45 g of chlorine, what
mass of sodium chloride is formed?
2. A 12.2-g sample of X reacts with a
sample of Y to form 78.9 g of XY.
What is the mass of Y that reacted?