1. Each piece of your clothing has a label that recommends cleaning methods. A 100%-cotton shirt may need to be ironed after washing. A cotton and polyester blend fabric may come out of the dryer wrinkle free. There is no cleaning process that works for all materials.

2. Pure Substances
A pure substance is matter that always has exactly the same ___________________________.
Table salt and table sugar are two examples of pure substances.
Substances can be classified into two categories—elements and compounds.
Every sample of a given substance has the same properties because a substance has a fixed, ______________composition.

3. Elements
An element is a substance that_________be broken down into simpler substances.
An element has a fixed composition because it contains only one type of ___________.
No two elements contain the same type of atom.
Examples of Elements
Solids at room temperature: Most soft drink cans are made from aluminum. Carbon is the main element in the marks you make with a pencil.
Oxygen and nitrogen are the main gases in you breathe.
Two elements are liquids at room temperature–bromine and mercury.

4. Symbols for Elements
Chemists use symbols of one or two_________to represent elements.
The first letter is always_____________. If there is a second letter, it is not capitalized.
Symbols allow scientists who speak different languages to communicate without _________________.
C represents carbon.
Al represents aluminum.
Au represents gold. (The Latin name is aurum.)
Gold
Aluminum
Carbon
Iodine

5. Compounds
A compound is a substance that is made from two or more simpler substances and __________broken down into those simpler substances.
A compound always contains two or more elements joined in a fixed proportion.
The properties of a compound____from those of the substances from which it is made.
Water: Oxygen and hydrogen are gases at room temperature, but water is a liquid.

6. Compounds
Silicon dioxide is a compound found in most light-colored grains of sand and in crystals of quartz. It is a colorless, transparent solid. Yet, silicon dioxide is made from a colorless gas (oxygen) and a gray solid (silicon). In silicon dioxide, there are always two oxygen atoms for each silicon atom.
Oxygen
Silicon
Silicon dioxide

7. Mixtures
If you make salsa, a recipe can guide you. You can use exactly the amounts in the recipe, or you can adjust the ingredients to your own taste. Salsa is a mixture. Each batch may be slightly different.

8. Mixtures
The properties of a mixture can vary because the composition of a mixture is not __________.
Mixtures can_______some of the properties of their individual substances.
The properties of a mixture are less constant than the properties of a substance.

9. Mixtures
Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture.
Heterogeneous Mixtures
In a heterogeneous mixture, the parts of the mixture are noticeably__________________from one another.
Homogeneous Mixtures
In a homogeneous mixture, the substances are so evenly distributed that it is difficult to___________one substance in the mixture from another.

10. Mixtures
The sand is a heterogeneous mixture of different kinds of grains.
The spoon is stainless steel, a homogeneous mixture of iron, chromium, and nickel.
The_________of the particles in a mixture has an effect on the properties of the mixture.

11. Solutions, Suspensions, and Colloids
Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.
Solutions
When substances________and form a homogeneous mixture, the mixture that forms is called a solution.
Suspensions
A suspension is a heterogeneous mixture that separates into___________over time.

12. Solutions, Suspensions, and Colloids
A colloid contains some particles that are ____________in size between the small particles in a solution and the larger particles in a suspension.
Like solutions, colloids do not separate into layers.
You cannot use a_____to separate the parts of a colloid.

13. Solutions, Suspensions, and Colloids
These liquids represent three categories of mixtures.
Windshield wiper fluid is a solution.
Muddy water collected from a swamp is a suspension.
Milk is a colloid.