• Pure substance: matter that has a fixed
(constant) composition and unique
properties. Contains only 1 type element or
compound; homogeneous
Mixture:
Contains at least 2 PHYSICALLY
combined compounds; can be homogeneous
or heterogeneous
heterogeneous mixtures
Heterogeneous mixture : the components are not evenly
distributed among each other. An heterogeneous
mixture has two or more distinct phases that are usually
detectable. This type of mixture does NOT have uniform
properties.
Heterogeneous mixtures that look like solutions can be
distinguished because
they scatter light
(Tyndall effect).
Examples: Sand water,
oil and water, milk,
sulfur and iron, granite,
blood...
Heterogeneous matter
•
•
Means different throughout
Always a MIXTURE (solutions are mixtures that are
NOT heterogeneous)
• 2 or more PHYSICALLY combined
substances (elements/compounds)
• ex: blood, air, muddy water
Is it uniform throughout?
• If the answer is no, the matter is a
heterogeneous mixture.
– Considered the “least mixed.”
– Does not appear to be the same throughout.
– Particles are large enough to be seen and to be
separated from the mixture.
Examples of heterogeneous mixtures
• Sand and pebbles
• Oil and water
• Powdered iron and powdered sulfur
Granite is a heterogeneous mixture.
Homogeneous Substances
• Means same throughout
1) element: only 1 type of atom
2) compound: 2 or more CHEMICALLY combined
elements (not easily separated from each other)
ex: water, CO2
3) Solution: a special kind of mixture 2 phases/parts
(SOLUTE dissolves & SOLVENT does the dissolving)
ex: moist air (H2O in Air); sterling silver (Cu
in Ag…called an alloy)
Homogeneus mixtures
Homogeneous mixtures : is a mixture in which the
components are evenly distributed among each other.
You can’t see the component parts.
Homo means the same throughout.
It has a constant composition throughout.
• Homogenous mixtures are also
called SOLUTIONS
Examples: Salt dissolved in water,
sugar dissolved in water, apple
juice, tea, copper (II) sulfate
solution in water, alloys....
• Matter can also be classified according to its
composition. Mixtures can be homogeneous
or heterogeneous.
• Mixtures can be separated into pure
substances, and pure substances can be
either compounds or elements.
Is it uniform throughout?
• If the answer is yes, the matter is
homogeneous (looks the same throughout).
• That leads us to another question.
Can it be separated by physical
means?
• If the answer is yes, the matter is a
homogeneous mixture or solution.
Homogeneous Mixtures
• A mixture that appears to be the same
throughout.
• It is “well mixed.”
• The particles that make up the mixture are
very small and not easily recognizable.
Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous
mixtures. They are also colloids.
Classification of Matter
uniform
properties?
fixed
composition?
chemically
decomposable?
no
heterogeneous
mixture
no
solution
no
element
yes
compound
Classification of Matter
Materials
Homogeneous
Heterogeneous
Element
Substance
Homogeneous
mixture
Compound
Solution
Order / Disorder
Heterogeneous
mixture
Mixture
Classification of Matter
• Now that we have defined chemical and
physical properties of matter, we can use that
to help us classify it.
• One way chemists classify matter is based on
its purity.
Classification of Matter
• Pure Substance – Matter that has only 1 set of
chemical and physical properties.
Example: Pure water always
has the exact same chemical
and physical properties
under the same conditions.
If water ever tastes different
then it isn’t pure water; it fits
into our next category.
Classification of
Matter
• Mixture – Two or more pue substances mixed
together. Each substance in the mixture retains
its own set of chemical and physical properties.
Example:
Copper and
Zinc can be
mixed
together to
produce
brass.
Classification of Matter
• Mixture – Two or more pure substances mixed
together. Each substance in the mixture retains
its own set of chemical and physical properties.
Unlike pure substances,
mixtures can always be
separated by physical
means.
How could we separate the
copper and zinc back out?
Mixtures
• Mixture – Two or more pure substances mixed
together. Each substance in the mixture retains
its own set of chemical and physical properties.
If a sample of sand
contains iron and salt,
how could you separate
them from the other
minerals?
Mixtures
• Some mixtures are more pure than others.
• Heterogeneous mixture – Uneven distribution
of substances. (Very impure)
- You can see the different parts.
Examples:
Sand
Granite
Wood
Mixtures
• Some mixtures are more pure than others.
• Heterogeneous mixture – Uneven distribution
of substances. (Very impure)
- You can see the different parts.
Examples:
Milk
Blood
Mixtures
• Homogeneous Mixture – Components are
evenly mixed. (More pure than heterogeneous)
- Cannot see the parts.
Salt water contains salt
and water, but are mixed
all the way to the atomic
level, but it can still be
separated by physical
means.
Seawater distillation plant
Pure Substances
• Pure substances can also be divided into 2
categories: compounds and elements.
Pure Substances
• Compound – Two or more elements chemically
bonded together.
Examples:
Carbon Dioxide (CO2)
Water (H2O)
Salt (NaCl)
Sucrose (C12H22O11)
Pure Substances
• Compounds have only 1 set of properties. They
cannot be separated by any physical process.
- Can only be separated by a chemical reaction.
Water can be
separated into
Hydrogen and Oxygen
by a process called
Electrolysis.
Pure Substances
• Elements – Substances made up of only one
type of atom.
- Cannot be separated by any physical OR
chemical process.
Examples:
Carbon
Helium
Gold
Matter
Can be
separated
physically
Pure
Substance
Mixture
Can see
the parts
Heterogeneous
Mixture
Most impure
Cannot be
separated
physically
Cannot
see the
parts
Homogeneous
Mixture
Can be
separated
chemically
Compound
Cannot be
separated
Element
Most pure