Chapter 2

Matter

MatterMatter – anything that has mass and takes up space

MassMass – measure of the amount of matter that an object contains

VolumeVolume – measure of the space occupied by the object

Extensive & Intensive Properties

What you observe when you examine a sample of matter is its properties.properties.

1.1. Extensive PropertyExtensive Property – a property that depends on the amount of matteramount of matter in a sample

Ex. Mass, volume, weight, length

2.2. Intensive PropertyIntensive Property – a property that depends on the type of mattertype of matter in a sample (prefix–in means within)

Ex. Hardness, color, odor, luster, conductivity, malleability, ductility, freezing point, boiling point, melting point, density

SubstancesSubstanceSubstance – Matter that has a uniform and definite

composition

• Either an element or a compound

• Also called pure substance

• Rarely found in nature

• Fixed proportions to each other

ExamplesExamples

Diamond Water

Gold Copper

Sugar Nitrogen

MixturesMixtureMixture – a physical blend of two or more

substances that are not chemically combined

• Do not exist in fixed proportions to each other

• Most natural substances are mixtures

• Can usually be separated back into its original components

ExamplesExamples

Concrete Soil

Salt water Milk

Coke Gasoline

Fruit salad Atmosphere

ExamplesExamples

Concrete Soil

Salt water Milk

Coke Gasoline

Fruit salad Atmosphere

Two Types of Mixtures

Homogeneous Mixture (solution)Homogeneous Mixture (solution) – a mixture in which the composition is uniform throughout.

• Consists of a single phase

• Can’t see them separately or separate them physically

ExamplesExamples

stainless steel

air

olive oil

vinegar

Two Types of Mixtures

Heterogeneous Mixture Heterogeneous Mixture – a mixture in which the composition is not uniform throughout.

• Consists of a two or more phases

ExamplesExamples

chicken soup

oil & vinegar mixed

milk

rice crispy treats

Separating Mixtures

Differences in physical properties can be used to separate mixtures

ExamplesExamples

coffee filters

draining pasta

Filtration Filtration – process that separates a solid from a liquid

Separating Mixtures

ExampleExample

separating water from other substances in the water

Distillation Distillation – process of boiling a liquid to produce a vapor and then condensing the vapor into a liquid

States of Matter

1. Solid1. Solid

2. Liquid2. Liquid

3. Gas3. Gas

States of Matter

SolidSolidDefinite shapeDefinite volume

Not easily compressed

CharacteristicsCharacteristics• Does not take the shape of the container• Particles packed tightly together, and often in orderly

arrangement• Almost incompressible• Expands only slightly when heated

States of Matter

LiquidLiquidIndefinite shapeDefinite volume

Not easily compressed

CharacteristicsCharacteristics• Take the shape of the container in which it is placed• Particles in close contact, but arrangement of particles

is not orderly (can flow past each other)• Almost incompressible• Expands slightly when heated

States of Matter

GasGasIndefinite shapeindefinite volume

Easily compressed

CharacteristicsCharacteristics• Take the shape of the container in which it is placed• Can expand to fill any volume• Particles are much farther apart• Easily compressed into a smaller volume

Physical Change

Physical ChangePhysical ChangeSome properties of a material change, but the composition of the material does not change

ExamplesExamples Changes of stateChanges of state such as boiling water,

condensation (boil, freeze, melt, condense)

Physical deformationPhysical deformation such as cutting, denting, stretching, breaking, crushing

Chemical Change

ExamplesExamples Silver spoon tarnishes

Metal rusts Methane burns

Methane burns Sugar ferments

Burn, rot, rust, decompose, ferment, explode, corrode usually mean a chemical change

Chemical ChangeChemical ChangeA change that produces matter with a different composition than the original matter

Elements

Element Element – simplest form of matter that has a unique set of properties.

• cannot cannot be broken down into simpler substances

ExamplesExamples Hydrogen

Nitrogen

Oxygen

Compounds

CompoundCompound – substance that contains two or more elements chemically combined in a fixed proportion.

• Compounds can be broken down into simpler substances by chemical means

ExamplesExamples

Sugar (C12H22O11)

Salt (NaCl)

Water (H2O)

Breaking Down Compounds

A chemical change is required to breakdown compounds into simpler substances

Some methodsSome methods

Heating

Sugar heat Carbon + Water compound element element

Electric current

Water electricity Hydrogen + Oxygen compound element element

Properties of Compounds

In general, properties of compounds are quite different from those of their component elements.

ExampleExample

Compound ---- Table Salt (NaCl)

Element ---- Sodium (Na) – soft, gray metal

Element ---- Chlorine (Cl) – pale yellow-green poisonous gas.

ElementElementSimplest form

CompoundCompound

SubstanceSubstanceDefinite composition

HomogeneousHomogeneousMixtureMixture

Uniform; also calleda solution

HeterogeneousHeterogeneousMixtureMixture

Nonuniform;Distinct phases

MixtureMixtureVariable composition

MatterMatter

Can be separated physically

Can be separatedchemically

Silver Salt StainlessSteel

Cement

Classifying MatterAny sample of matter is either an element, a compound, or a mixture

Chemical Symbols

Each element on the periodic table is represented by a one or two letter chemical symbol.

ExamplesExamples

Na – Sodium Au - Gold

C - Carbon K - Potassium

• The first letter of a chemical symbol is always capitalized.

• When a second letter is used, it is lowercase

Symbols Derived From Latin

Sodium Na

Potassium K

Antimony Sb

Copper Cu

Gold Au

Silver Ag

Iron Fe

Lead Pb

Tin Sn

Physical PropertiesPhysical PropertyPhysical Property – a quality or

condition of a substance that can be observed or measuredobserved or measured without changing the substance’s composition

ExamplesExamples

Appearance Density

Texture Malleability

Color Boiling Point

Odor Melting Point

Conductivity Hardness

Chemical Property

ExamplesExamples

Gasoline -- burns in air Iron -- rusts Baking Soda -- reacts with vinegar Copper -- rusts in waterTable salt -- does not react with vinegar

Chemical Property Chemical Property Ability of a substance to undergo a specific chemical change

• Chemical properties can be observed only when a substance undergoes a chemical change.

Recognizing Chemical Changes

ExamplesExamples

Gasoline -- burns in air Iron -- rusts Baking Soda -- reacts with vinegar Copper -- rusts in waterTable salt -- does not react with vinegar

Words such as burn, rot, rust, decompose, ferment, explode, and corrode usually signify a chemical change.

During a chemical change, the compositionof matter always changes.

Recognizing Chemical Changes

Precipitate – Precipitate – solid that forms and settles out of a liquid mixture

Ex.Ex. – ring of soap scum in your bathtub

Possible Clues Possible Clues •Transfer of energy•A change in color•The production of gas•The formation of a precipitate

The only way to be sure a chemical change has occurred is to test the composition of a

sample before and after the change

Law of Conservation of MassDuring any chemical reaction, the mass of the

products is always equal to the mass of the reactants.

ExampleExample

2H2 + O2 2H20

2g 2g = 4g

reactants = product