Bell Ringer What is Chemistry? How does affect your life?

Bell Ringer

What is Chemistry?

How does affect

your life?

Matter

Matter is anything that:Has mass &Takes up space

What is Matter?

Different materials different properties

different materials have different compositions (i.e. different stuff)

Clothing labels no cleaning process works for

all materials.

Matter

Matter is divided into 2 categories:

Matter

Matter that always has exactly the same composition.

Every sample has the same properties

Examples: Table salt and table sugar

Pure Substances

Two categories of pure substances:

• Elements

• Compounds.

Matter

Matter

Cannot be broken down into simpler substances.

Fixed compositionContains only one type of atom.

The atoms of each element are unique.

Elements (First Category of Pure Substances)

Examples of Elements you may have heard of:

Aluminum - Most soft drink cans made from it.

Carbon - main element in pencil marks.

Oxygen and Nitrogen - main gases in the air.

Bromine and Mercury - two elements that are liquids at room temperature

(Most elements are solids at room temperature.)

Elements

Symbols for Elements

Chemical symbols have one or two lettersFirst letter is always CAPITALIZED

If there is a second letter, it is lower case

•C represents carbon.

•Al represents aluminum.

•Au represents gold.

(The Latin name for gold is aurum)

Elements

Symbols for Elements are universal

Even when the names are different in different languages

N is the symbol for the element we (American English speakers) call nitrogen:

French word is azote

German word is stickstoff

Spanish word is nitrógeno in Mexico.

Elements

Pictures of pure elements you might encounter

(most elements are not found in pure form)

Elements

Aluminum Carbon Gold Iodine

A compound contains two or more elements joined in a fixed proportion.

Compounds (Second Category of Pure Substances)

Compound is:•Made from two or more simpler substances•Can be chemically broken down into those simpler substances.

Properties of a compound are different from those of the substances from which it is made.

Example: Water – composed of H and O.

• Oxygen and hydrogen are gases at room temperature

•Water is a liquid at room temp.

• Hydrogen can fuel a fire

• Oxygen can keep a fire burning

•Water does not burn

Compounds

Another Example:

Sodium Chloride, composed of Na and

Cl. (common table salt)

•Sodium and Chlorine are highly reactive, toxic (poisonous) materials.

•Sodium Chloride is necessary for life

Compounds

Matter

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.

Mixtures

Composition of a mixture is not fixed.The properties of a mixture are less constant than the properties of a substance.

The properties of a mixture can vary

May vary in different parts of the mixture.

May vary when made at different times.

Some properties of the individual substances may be retained.

Mixtures

Heterogeneous

Mixture substances are noticeably different from one another.

Homogeneous

Substances are so evenly distributed that it is difficult to distinguish one substance from another.

Two Types of Mixtures

Two Types of 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.

Mixtures - Heterogeneous Example

Mixtures are classified based on size of largest particles

a solution (homogeneous)

a suspension (heterogeneous)

a colloid (it depends!)

Solutions, Suspensions, and Colloids

• The size of the particles in a mixture has an effect on the properties of the mixture.

Mixtures

SolutionDissolves

(tiniest particles are thoroughly mixed together)

Homogeneous mixtureSolute – the substance that is dissolved.

Solvent – the substance that does the dissolving.

Example: Lemonade

The sugar and lemon juice are solutes

The water is the solvent

Solutions, Suspensions, and Colloids

Solubility = substances’ ability to dissolve.

Soluble means it will dissolve.

Example, Salt is soluble in water.

Insoluble means it will NOT dissolve.

Example, Oil is insoluble in water.

Solutions, Suspensions, and Colloids

Suspension

Heterogeneous mixture

Separates into layers over time.

Example: muddy river water

Solutions, Suspensions, and Colloids

Colloids Particles’ size between the small particles in a solution and the larger particles in a suspension.

Particles are mixed together, but not dissolved.

Won’t separate into layers (same as a solution)

Cannot separate parts with filterOften appears Cloudy.

Examples: Fog, Smoke,

Foam, Latex paint

Solutions, Suspensions, and Colloids

Alloys

Metal Solutions

Solids that are dissolved in solids.

Examples:Gold Jewelry: solid solution of gold & copper

Brass: copper and zinc solid solution

Sterling Silver – contains small amounts of copper in solution with silver

Stainless Steel: alloy of chromium and iron

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.

Solutions, Suspensions, and Colloids

Mixtures