• 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

no

no

yes

hetero- geneous mixture

solution

element

compound

Classification of Matter

Materials

Homogeneous

Heterogeneous

Heterogeneous mixture

Homogeneous mixture

Substance

Element Compound Solution Mixture

Order / Disorder

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)

Salt water contains salt and water, but are mixed all the way to the atomic level

- Cannot see the parts.

, 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

Mixture Pure Substance

Element Compound Heterogeneous Mixture

Homogeneous Mixture

Can be separated physically

Cannot be separated physically

Can see the parts

Cannot see the parts

Can be separated chemically

Cannot be separated

Most impure Most pure