Chapter 3. Matter – anything that has mass and takes up space Everything around us Mass:...

Chapter 3

Matter – anything that has mass and takes up space

Everything around us Mass: measurement that reflects the amount of matter (usually in grams) Volume: the amount of space something takes up

Chemistry – the study of matter and the changes it undergoes

Solids particles vibrate but can’t move

around fixed shape fixed volume incompressible

Liquids particles can move

around but are still close together

variable shape fixed volume Virtually incompressible

Gases particles can separate and

move throughout container variable shape variable volume Easily compressed Vapor = gaseous state of a

substance that is a liquid or solid at room temperature

Plasma atoms collide with enough energy to

break into charged particles (+/-) gas-like, variable

shape & volume stars, fluorescent

light bulbs, TV tubes

II. Properties & Changes in Matter (p.73-79)

Extensive vs. Intensive

Physical vs. Chemical

Physical Property

can be observed & measured without changing the identity of the substance

Physical properties can be described as one of 2 types:

Extensive Property depends on the amount of matter present

(example: length, mass, volume)

Intensive Property depends on the identity of substance, not

the amount (example: scent, density, melting point)

Derived units = Combination of base units

Volume (m3 or cm3 or mL) length length length Or measured using a

graduated cylinder

D = MV

1 cm3 = 1 mL1 dm3 = 1 L

Density (kg/m3 or g/cm3 or g/mL)mass per volume

Chemical Property describes the ability of a substance to be

observed reacting with or changing into another substance

Examples: melting point

flammable

density

magnetic

tarnishes in air

physical

chemical

physical

physical

chemical

Physical Change changes the form of a substance without

changing its identity

properties remain the same

Examples: cutting a sheet of paper, breaking a crystal, all phase changes

Evaporation =

Condensation =

Melting =

Freezing =

Sublimation =

Liquid -> Gas

Gas -> Liquid

Solid -> Liquid

Liquid -> Solid

Solid -> Gas

Temp, oC

Solid only, Q = m ΔT Cpsolid

Q = mol x ΔHfusion

Solid & liquidLiquid onlyQ= m ΔT Cpliquid

Q = mol x ΔHvapor

Liquid & gas

Time, min

Temperature vs. Time

Gas Only

Process that involves one or more substances changing into a new substance Commonly referred to as a chemical

reaction New substances have different

compositions and properties from original substances

Reaction involves reactants reacting to produce products

Signs of a Chemical Change

change in color or odor

formation of a gas (bubbles)

formation of a precipitate (solid)

change in light or heat

Examples: rusting iron

dissolving in water

burning a log

melting ice

grinding spices

chemical

physical

chemical

physical

physical

Exothermic- heat energy EXITS the system

surroundings usually feel warmer1 g H2O (g) 1 g H2O (l) + 2260 Jex. Combustion, evaporation of

water

Endothermic- heat energy ENTERS the system- heat absorbed from surroundings

- surroundings usually feel cooler - 1 g H2O (s) + 333 J 1 g H2O (l)

- 1 g H2O (l) + 2260 J 1 g H2O (g)- ex. Cold packs, melting ice

Although chemical changes occur, mass is neither created nor destroyed in a chemical reaction

Mass of reactants equals mass of products

massreactants = massproducts

A + B C

III. Classification of Matter (pp. 80-87)

Matter Flowchart

Pure Substances

Mixtures

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Examples: graphite

pepper

sugar (sucrose)

paint

soda

element

hetero. mixture

compound

hetero. mixture

solution

Element composed of one type of identical atoms EX: copper wire, aluminum foil

Compound

composed of 2 or more elements in a fixed ratio (bonded together)

properties differ from those of individual elements

EX: table salt (NaCl)

Variable combination of 2 or more pure substances, each retains its chemical identity & properties.

Heterogeneous Homogeneous

Homogeneous: are uniform throughout Solutions very small particles particles don’t settle EX: rubbing alcohol, gasoline, soda

Heterogeneous medium-sized to

large-sized particles

particles may or may not settle

EX: milk, fresh-squeezed

lemonade

Examples: tea

muddy water

fog

saltwater

Italian salad dressing

Answers: Solution

Heterogeneous

Heterogeneous

Solution

Heterogeneous

1. Metals: usually solid, good conductors of heat/electricity, malleable, and ductile

2. Nonmetals: solid, liquid or gas, brittle, poor conductors

3. Metalloids: transition between metals and nonmetals, semiconductors

Atom: Composed of protons, electrons, and

neutrons Smallest particle of matter that can be

identified as one elementMolecules:

A collection of atoms chemically bonded together

May be element or compound

Electron: Negative charge Used in bonding (very mobile)

Proton: Positive charge Located in nucleus Determine identity of atom

Neutron Neutral (no charge) Helps determine mass of the atom Located in nucleus

+

Separation Methods

Ways to separate mixtures – Chapter 3: Matter & Its Properties

+Separating Mixtures

Substances in a mixture are physically combined, so processes bases on differences in physical properties are used to separate component

Numerous techniques have been developed to separate mixtures to study components Visually Magnetism Filtration Distillation Crystallization Chromatography

+Filtration

Used to separate heterogeneous mixtures composed of solids and liquids

Uses a porous barrier to separate the solid from the liquid

Liquid passes through leaving the solid in the filter paper

+Distillation

Used to separate homogeneous mixtures

Based on differences in boiling points of substances involved

+Crystallization

Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance

As one substance evaporates, the dissolved substance comes out of solution and collects as crystals

Produces highly pure solids

Rocky candy is an example of this

+Chromatography

Separates components of a mixture based on ability of each component to be drawn across the surface of another material

Mixture is usually liquid and is usually drawn across chromatography paper

Separation occurs because various components travel at different rates

Components with strongest attraction for paper travel the slowest