Unit 1Chapter 2-pg38

Matter and ChangeChemistry 334

Essential Question:

How do chemists classify matter?

Section 2.1Properties of Matter

Describing MatterKC: How can Properties be used to describe

matter?

A: Properties used to describe matter can be classified as ether extensive or intensive.

Extensive PropertiesA property that depends on the amount of

matter in a sample.

Examples of extensive properties:

Mass—the amount of matter an object contains.

Volume—the measure of the space occupied by an object.

Intensive Properties:A property that depends on the type of matter in

a sample, not the amount.

ExamplesHardnessOdorConductivityState of matter

*******What it is made of******

Identifying SubstancesKC: Why do all samples of a substance have the

same intensive properties?

Every sample of a given substance has identical intensive properties because every sample has the same composition.

SubstanceMatter that has definite and uniform

composition.

AKA: Pure substance

Examples: AuAgNaClCH4

NaCl vs. NaCl Water (H2O)Q: Is salt water a pure substance????

INDEX CARD CHALLENGE!!!!

INDEX CARD CHALLENGEWithout talking, find someone who has a

different answer that you

IDK—does not count as an answer!!!

Explain why you chose this answer.

The AnswerNaCl is a pure substance

Salt water is not It can have variable composition

Physical PropertiesPhysical property—any quality or condition of a

substance that can be observed without changing the substance’s composition.

Examples:StateMpBpColor

States of matter:KC: What are 3 states of matter?

A: Three states of matter are solid, liquid, gas.

SolidDefinite shape

Definite volume

Not easily compressed

LiquidIndefinite shape

Definite volume

Not easily compressed

GasIndefinite shape

Indefinite volume

Easily compressed

Three States of Matter

VaporDescribes the gaseous state of a substance that

is generally a liquid or solid at room temperature.

Physical ChangesKC: How can physical changes be classified?

A: Physical changes can be classified as reversible or irreversible.

ReversiblePhase changes

MeltingFreezing SublimationBoilingCondensation

IrreversibleBreaking

Tearing

Smashing

Cutting

Section 2.2 MixturesPage 44

Classifying MixturesKC: How can mixtures be classified?

A: Mixtures can be calssified as either hetterogenous or homogenous.

MixtureA combination of two or more

pure substance.

Can be made with different combinations of solid, liquids and gasses.

2 Types of mixtures1. Homogenous

2. Heterogenous

Heterogeneous MixtureNot the same through out

More than one phase

(distinguishable parts) ie:

Chicken noodle soup Chex mix

Homogenous mixtureUniform composition; same through out

AKA: SolutionOnly one phase ie:

Salt waterTeaOlive oilVinegarAlloy

Separating MixturesKC: How can mixtures be seperated?

A: Differences in physical properties can be used to separate mixtures.

5 ways to separate mixtures

1. Filtration

2. Distillation

3. Crystallization

4. Sublimation

5. Chromatography

FiltrationA technique which uses a pours barrier to

separate a solid from a liquid

DistillationA separation technique that is based on the

differences in the boiling points of the mixed substances

CrystallizationA separation technique that results in the

formation of pure solid particles of a substance from a solution containing the dissolved substance.

SublimationThe process during which a solid changes to a

vapor without going through the liquid phase

ChromatographyA technique that separates the components of a

mixture (aka-mobile phase), based on the ability of each component to be drawn across the surface of another material (aka-stationary phase).

Section 2.3Elements and Compounds

Distinguishing Elements and Compounds

KC: How are elements and compounds different?

A: Compounds can be broken down into simpler substances.

Examples of elementsCa

Na

H

Periodic TableOrganizes the elements into a grid of horizontal

rows (aka-periods) and vertical columns (aka- groups/families).

CompoundsTwo or more elements combined chemically

Breaking Down Compounds

Compounds can be broken down by chemical change

This process usually requires a an external energy source, such as heat or electricity

Properties of CompoundsThe chemical and physical characteristics of a

compound is very different than that of its constitute parts.

Example:K + I KI

Potassium & Iodine VS Potassium iodide

Potassium A light silver metal that reacts with water

IodineA black solid that changes to a purple gas at

room temperature.

Potassium iodide A white salt

Distinguishing Substances and Mixtures

KC: How can substances and mixtures be distinguished?

A: If the composition of a material is fixed, the material is a substance. If the composition of the substance may vary, the material is a mixture.

Classification of matter

Ex: chex salt NaCl Na

mix water

(AKA: solutions)

Symbols and formulasKC: What do chamists use to represent elements

and compounds?

A: Chemists use chemical symbols to repersent elenents and chemical formulas to represent compounds

Chemical SymbolOne or two letters used to represent the name of

an element.

Chemical Compounds

Section 2.4Chemical Reactions

Chemical ChangesKey Concept: What always happens during a

chemical change?

Answer: During a chemical change, the composition of matter changesExample

combustion reaction

Examples:Fe to Rust

Respiration

Combustion (candle burning vs. wax melting)

Words that indicate a chemical change:

-Decompose -Ferment -Tarnish

-Oxidize -Burn -Rust

-Corrode -Rot -Explode

Chemical Properties=The ability (or inability) of a

substance to combine with or change into one or more substances.

Chemical ChangeOne or more substances changes into one or

more new substances.

AKA: Chemical reaction

Mg + HCl H2 + MgCl

Reactants The substance that are to be transformed.

ProductThe substance(s) that are made

Recognizing Chemical Changes

Key Concept: What are the 4 possible clues that a chemical change has taken place?

Answer: Possible clues that a chemical reaction has taken place include: transfer of energy (heat or light), a change in color, the production of gas, or the formation of a precipitate.`

Precipitate=The production of a solid.

Conservation of MassKey concept: How are the masses of the

reactants and the masses of the products of a reaction related?

Answer: During any chemical reaction the mass of the reactants is always equal to the mass of the products.

Law of Conservation of Mass:

Massreactants=Massproducts

Practice Problems2Mg + O2 2 MgO

Mass of Magnesium

(g)

Mass of Oxygen(g)

Mass of Magnesium oxide

(g)

5 3.3 8.3

6.5 A 10.8

13.6 9 B

C 12.5 31.5

Words that indicate a chemical change:

-Decompose -Ferment -Tarnish

-Oxidize -Burn -Rust

-Corrode -Rot -Explode

Physical Changes=A change which alters a

substance without changing its composition.

Examples of physical changes:

CuttingBrakingPhase Change=transition of

mater from one state to another.

Chemical changes vs. physical changes

Physical Changes

Alters a substance without changing its composition (arrangement of its atoms)

Does NOT change the arrangement of atoms

SAME substance!

Chemical Changes

Alters a substance by changing its composition (arrangement of its atoms)

DOES change the arrangement of atoms

NEW substance made!

Chemical/Physical changes Foldable