Chapter 9: Classification of Matter Mr. Skelton. 9-1: Composition of Matter MatterMatter is anything that has mass & takes up space. Matter can be subdivided.

Chapter 9: Chapter 9: Classification of Classification of

MatterMatter

Chapter 9: Chapter 9: Classification of Classification of

MatterMatterMr. SkeltonMr. Skelton

9-1: Composition of Matter

• MatterMatter is anything that has mass & takes up space.

• Matter can be subdivided into two groups.

* substances * mixtures

Substances can be either

Elements•Made of only one kind of atom•92 naturally occurring elements•26 synthetic ones•Cannot be broken down by physical means

Compounds•Two or more elements that are chemically combined in a specific ratio.

•Examples: H2O = 2:1

NaCl= 1:1•Cannot be broken down by physical means.

Mixtures

• A combination of two or more substances that do not combine chemically, but remain the same individual substances

• They can be separated by physical means

• Two types:–Heterogeneous–Homogeneous

Based on the prefixes“hetero” and “homo,” what do you think are characteristics of thesetwo types of mixtures?

Heterogeneous Mixture

• “Hetero” means different• These mixtures have large particles

that can be easily separated. • A suspension is a special type of

heterogeneous mixture with even larger particles that eventually settle

• Example:

Trail Mix

Notice thevisibly

differentsubstance

s

Other Examples of suspensions include: Salad Dressing. Muddy Water, Juice (that

settles)

Heterogeneous MixturesColloids

• Colloids – large particles that scatter light. This is called the Tyndall effect.

• Examples: milk, fog, smog, dust, Jell-O, whipped cream

Homogeneous Mixture

• “Homo” means the same • These mixtures have very small

particles that are evenly spread throughout the mixture giving it a uniform appearance

• Commonly referred to as solutions• Example:

Salt WaterStainless SteelSodaCoffeeTea

Notice theuniform

appearance

Composition of Matter Concept Map

Matterclassifi

ed

as

classified as

examples

Which

inclu

de

Compounds

which include

are made up of

which include

examples examples

which include

which include

MixturesSubstances

Elements

Atoms (Same)

Atoms (Different)

Homogeneous

Heterogeneous

Colloids Suspensions

Solutions

Solution• a mixture of two or more substances that is

identical throughout• can be physically separated• composed of solutes and solvents

the substance in the smallest amount that gets dissolved in

the solvent

the substance in the larger

amount that dissolves the solute

Iced Tea Mix(solute)

Water(solvent)

Iced Tea(solution)

Salt water is considered a

solution. How

can it be physically separated?

Solutes Change Solvents

• The amount of solute in a solution determines how much the physical properties of the solvent are changed

• Examples:

Lowering the Freezing Point

The freezing point of a liquid solvent decreases when a solute is dissolved in it.

Ex. Pure water freezes at 320F (00C), but when salt is dissolved in it, the freezing point is lowered.

This is why people use salt to melt ice.

Raising the Boiling Point

The boiling point of a solution is higher than the boiling point of the solvent.

Therefore, a solution can remain a liquid at a higher temperature than its pure solvent.

Ex. The boiling point of pure water is 2120F (1000C), but when salt is dissolved in it, the boiling

point is higher. This is why it takes salt water longer to boil than fresh water

Concentration

• the amount of solute dissolved in a solvent at a given temperature

•described as dilute if solvent has a low concentration of solute

•described as saturated if the solvent has a high concentration of solute

•described as supersaturated if the solvent contains more dissolved solute than can be absorbed

Solubility

• the amount of solute that dissolves in a certain amount of a solvent at a given temperature and pressure

• influenced by:

Temperature Pressure

Solids increased temperature causes them to be more soluble and vice versa

Gases increased temperature causes them to be less soluble and vice versa

Ex. Iced Coffee

Solids increased pressure has no effect on solubility

Gases increased pressure causes them to be more soluble and vice versa

Ex. Soda, “The Bends”

What do we call things that are not soluble?

9-2 The Colloid 9-2 The Colloid ConnectionConnection

9-2 The Colloid 9-2 The Colloid ConnectionConnection

The Colloid Connection

What is a colloid?

A heterogeneous mixture that never settles and scatters light because of large particles.

Examples:

Aside from food products, are there any other colloids we encounter?

Yes – both good and bad.

Let’s look at the good first…

When you turn on the faucet, is the water clean or dirty?

Clean (we hope!) But why?

Colloids! But how?

Water is first taken from a stream,

river, or reservoir.

It then goes into a tank where

LIME and ALUM are added.

LIME ALUM

LIME

ALUM

The LIME and the ALUM form a colloid that is a gel-like

substance.

The gel-like substance traps microorganisms and other particles.

The “dirty” gel then passes through fine sand, where it is trapped.

Leaving…

Nice clean water.

Colloids aren’t always good though…

Pollution

Unburned particles suspended in the air

Aka “soot”

CoagulationIn coagulation, small, suspended particles are attracted to each other. They clump together, forming a particle that is too big to remain suspended.

On to our favorite colloid – gelatin (Jell-o)

Gelatin is large strands weakly connected together.

When added to boiling water, the strands split apart.

Water molecules get trapped between the strands as the gelatin cools.

And the gelatin “hardens” into a semisolid colloid.

9-3 Describing Matter9-3 Describing Matter9-3 Describing Matter9-3 Describing Matter

Two classifications of the properties of matter.

• Physical Property– A characteristic of a substance that

you can observe without changing the substance.

– Examples include: size, shape, mass, temperature, density, volume, etc.

• Chemical property• Characteristic of a substance that

indicates how it will behave.• Examples include: rust, tarnish,

flammable, photosensitive, etc.

When matter undergoes a change, the change can be

classified as either a….

• Physical Change• Any change in a physical

property• Tearing a piece of paper,

melting, freezing, boiling, etc.

• Chemical change• A change in one

substance to produce another new substance.

• Examples include: rusting, tarnishing, cooking, burning, bubbling (like in alka-seltzer & water), reactions to light (like exposing film to light), etc.

Indications of chemical changes include a change in physical properties such as odor, color, bubbling, light, heat, sound, etc.

Plus the production of a

new substance.

Law of Conservation of Mass

• First developed by Antoine LaVoisier

• States that mass cannot be created or destroyed.

• This means that the total mass at the beginning of a chemical change will equal the mass at the end of the change.