Composition of
Matter
PROPERTIES OF MATTER
• What is matter?
Anything that has mass and takes up space
• What is mass?
The amount of matter an object contains
SUBSTANCES
• A substance is
matter that has a
definite and uniform
composition
One type of “stuff”
TYPES OF SUBSTANCES
• There are two different types of
substances:
One type of “stuff”
ELEMENTS
• An element is the simplest forms
of matter.
Carbon is an element
Elements are made of atoms
Diamonds are made of atoms of the
element Carbon
Foil is made of the atoms of the element
Aluminum.
• Each element is represented by a
chemical symbol.
Atoms are matter
• Carbon is an element
• Elements are made of atoms
• Diamonds are made of atoms of the
element Carbon
• Foil is made of the atoms of the element
Aluminum.
Atoms are matter
• Elements most abundant in the earth
and human body are:
Elements
• Pure substance that consists
entirely of one type of atom
Hydrogen
Sulfur
Magnesium
COMPOUNDS
• 2 or more elements combine to
make a compound
• A compound is a substance that
can be separated into simpler
substances only by chemical
means
COMPOUNDS
• Examples:
Water - H20
Salt - NaCl
Hydrogen Peroxide - H2O2
Molecules
• Smallest unit of a substance that exhibits
all of the properties characteristic of that
substance
• They act as a unit
– Example: water H2O
Molecules
• Most molecules are made of atoms of
different elements, but some can be made
of atoms of the same element.
TYPES OF MATTER
chemically
separable
MIXTURES
• A mixture is a physical
blend of two or more
substances that can
be physically
separated.
• How?
One type of “stuff”
More than one
type of “stuff”
together
Pure Substance
vs. Mixture
• When people say “Pure Grape Juice” this
means it contains only the juice of the
grapes with NOTHING added or taken
away
• In reality, grape juice is NOT a pure
substance. It is a MIXTURE!!!
Mixture
• A combination of more than one
substance
– Grape juice is a mixture because it
contains water, sugars, acids, and
vitamins
– The composition of grape juice is not
fixed; it can have different amounts of
water, sugars, or other compounds
MIXTURES
physically
separable
Not uniform
Uniform
throughout
HETEROGENEOUS vs. HOMOGENEOUS
• There are 2 different types of
mixtures.
– A heterogeneous mixture has more
than one phase or substance
(looks different)
– A homogeneous mixture has only
one phase (looks the same)
• Also called a SOLUTION
Heterogeneous
Mixtures
• Mixtures of this type are not the
same throughout.
– Example: Fruit Salad
• Each spoonful of fruit salad would give
you a different variety – no 2 spoonfuls
would be exactly the same.
Heterogeneous Mixture
SUSPENSION
a mixture that looks
uniform when
stirred or shaken
that separates into
different layers
when it is no longer
agitated
COLLOID
• Gelatin  heterogeneous mix
– Gelatin is a colloid
– Colloid a mixture of very tiny
particles of pure substances that
are dispersed in another
substance but do not settle out
of the substance
Colloids
• Differences between suspensions and
colloids:
• Particles in colloids are much smaller
• Because they are so small, they do NOT separate
out or settle to the bottom in colloids
• Particles stay dispersed throughout the mixture
Colloids
• EXAMPLES:
•
•
•
•
•
•
Fog
Milk
Shaving cream
Egg white
Paint
Blood
Types of Heterogeneous Mixtures
• Colloids
– Particles never settle
– Displays the Tyndall Effect
• Scattering of light particles
• Ex) Fog, milk, shaving cream
Homogeneous
Mixtures
• These mixtures are uniform, in
that no matter where you get
your sample from in the mixture
– each sample will be the exact
same.
– Examples: Kool-Aid, tomato soup,
salt water, brass keys
Homogeneous Mixtures
• Not only look uniform, they ARE
uniform
• Ex: Salt water
• If you add salt to a glass of pure water and
mix it, it will eventually look like pure water
• Looks uniform because the components of
the mixture are too small to be seen
Homogeneous Mixtures
• When salt and water mix, no chemical
reaction takes place
• Easy to separate the 2 substances by evaporating or
boiling the water
• Once boiled, only left with salt
homogeneous
heterogeneous
Solutions and Homogeneous mixtures
SOLUTIONS & HOMOGENEOUS
MIXTURES are synonymous.
Homogenous mixtures are mixed
completely, all the way down to their
most fundamental particles-atoms,
molecules, or ions.
Types of Heterogeneous Mixtures
• Colloids
– Particles never settle
– Displays the Tyndall Effect
• Scattering of light particles
• Ex) Fog, milk, shaving cream
• Suspensions
– Visible particles settle
– Require agitation to stay mixed
• Ex) OJ, Italian dressing, sand & water
HETEROGENEOUS OR HOMOGENEOUS?
• Saltwater
Homogeneous
• Spaghetti sauce
• Muddy water
Heterogeneous
Heterogeneous
• Cough syrup Homogeneous
• Salad
• Brass
Heterogeneous
Homogeneous