chapter 3 matter – properties & changes. introduction: what is matter?

Chapter 3

Matter – Properties & Changes

Introduction:

What is matter?

Introduction Matter – anything that has mass and

volumeThe atom is the building block of all

matter

States of Matter

What are the 3 main states of matter?

States of Matter

SolidHas definite shape & volumeParticles are tightly packedCan expand when heated

States of Matter

LiquidHas constant volume but takes the shape

of its containerFluidLess closely packed particles than solid

particlesCan expand when heated

States of Matter

GasExpands to fill its container & takes the

shape of its containerFluidMuch less closely packed than solid

particlesExpands when heated

States of Matter 1)

2)

3)

States of Matter - Plasma

PlasmaDoes not naturally occur on Earth (except in

lightning) Present in the Sun

An ionized gas Sufficient energy is provided to

free electrons from atoms or molecules and to allow both ions and electrons to coexist

Phase Changes

When a substance freezes, boils, evaporates, or condenses, it undergoes a phase changeThe addition or removal of energy is

what causes phase changesThis change is also a physical change

Phase Changes

Matter

Mixtures Pure Substances

Heterogeneous

Homogeneous

Element

Compound

Types of Matter Mixtures

1. Physical combinations of 2 or more substances

2. Components do not chemically react with each other

Pure Substances1. Elements

2. Compounds

Mixtures

Mixture – a combination of two or more pure substances in which each pure substance retains its individual chemical properties

2 kinds: Heterogeneous Homogeneous

Heterogeneous Mixtures

Mixture that does not blend smoothly throughout – individual substances remain distinct

Homogeneous Mixtures Mixture that has constant composition

throughoutExamples: salt water, soda water, brass

A.k.a. a solutionSolute in a solvent (salt dissolved in water)

Separating Mixtures Filtration – separates undissolved solids

from liquidsUsed to separate heterogeneous mixtures

Separating Mixtures Distillation – separates a solution of liquids

or a homogeneous mixture

Separating Mixtures Crystallization

Separates dissolved solids from liquids

Crystallization Demo & Explanation

Crystallization Demo

Separating Mixtures Chromatography – separates components of a

solution into its components based on tendency to travel on another surface

Elements

Elements – pure substance that cannot by separated into simpler substances by physical or chemical meansMade of only 1 type of atomAll elements are found on the Periodic Table

of ElementsEach has a unique name & symbol

Ex.) Carbon (C), oxygen (O), platinum (Pt)

Elements All elements have a unique symbol

Each symbol is either 1 or 2 letters One letter = capitalized Two letters = first is capitalized, second is not

Symbols are often similar to the name but sometimes they are derived from the Latin name Ex.) Mercury’s symbol = Hg (from Latin hydrargyrum)

Compounds Compound – combination of 2 or more

elements chemically bonded together or combinedWritten with a chemical formula

Letters indicate the elements in the compound Subscripts indicate the # of each type of atom in

the molecule

Compounds The properties of a compound are VERY

DIFFERENT from the properties of the individual elements they contain

Ex.) Sodium Chloride (NaCl) vs. Sodium & Chlorine

Sodium: Sodium in Pond

Sodium in 40 Gallon Trashcan

Compounds A molecule is the smallest particle of a

compound Compounds have constant composition

from one sample to another

Matter

Mixtures Pure Substances

Heterogeneous

Homogeneous

Element

Compound

In Review…

Classify the following as element, compound, heterogeneous mixture, or homogeneous mixture:

Law of Definite Proportions

Elements in a compound combine in definite proportions by massAll samples of a compound have the same

proportion by mass of the elements present.

100compound of mass total

element of mass massby percent

Example – Law of Definite Proportions

If 1.0 g of hydrogen reacts completely with 19.0 g of fluorine, what is the percent by mass of hydrogen in the compound that is formed?

Example – Law of Definite Proportions

If you have a sample of sucrose (a type of sugar), you will always have 42.2% of carbon, 6.50% of hydrogen, and 51.30% of oxygen, no matter where you find that sample. Therefore, if you are given 50.0 g of sucrose, how many grams of each element will you have?

Law of Multiple Proportions

When different compounds are formed by the combination of the same elements, they will combine in small whole number ratiosEx.) H2O & H2O2 ; CuCl & CuCl2 ; CO & CO2

Properties of Matter

When talking about the properties of matter, there are two types:

PHYSICAL properties

OR

CHEMICAL properties

Physical Properties of Matter

Characteristic that can be observed or measured without changing the sample’s composition (or identity)Ex.) color, boiling point, state of matter,

density

Physical properties describe appearance or behavior

Physical Properties of Matter

Extensive propertyDepends on the amount of substance presentExamples:

Mass Length Volume

Physical Properties of Matter

Intensive property Independent of the amount of substance

presentExamples:

Color Density Smell Boiling point

Physical Properties of Matter

Intensive or Extensive?1. Phase

2. Size

3. Odor

4. Flammability

5. Energy

6. Melting point

Chemical Properties of Matter

Chemical property – the ability of a substance to combine with or change into one or more other substances Examples: rusting, flammability, light sensitivity

2 H2O2 (l) 2 H2O (l) + O2 (g)

Observing Properties of Matter

When recording physical or chemical changes, note the conditions. Many properties of substances can depend on temperature or pressure!

Physical Changes

Physical changes – altering a substance without changing its identity or composition

Examples:CuttingBreakingPhase changes (evaporation, condensation,

sublimation, etc.)

Chemical Changes

Chemical changes - one or more substance changes into a new substance i.e. a new substance is formed

Examples: burning, rotting, rusting

4 Fe + 3 O2 2 Fe2O3

Evidence of a Chemical Change Properties of new substance formed does

not have the same properties as the original substance

Signs a chemical change has occurred:HeatCoolingFormation of bubbles (gas produced)Formation of solidsColor change

Chemical or Physical Change?

1) Butter melting

2) Hot glass cracking when placed in cold water

3) Dissolving sugar in water

4) Burning sugar (like on crème brulee)

5) Wood rotting

6) Burning gasoline in your car

7) Silver tarnishing

Weathering of the Earth – Chemical or Physical Changes?

Physical changes include:The splitting of rocks by freeze thaw cycles does

not change the make up of the rock

The cutting through and wearing away of softer rock by the actions of water

Weathering of the Earth – Chemical or Physical Changes?

Chemical changes include:The dissolving of rock by slightly acidic waterLimestone easily dissolves in acidic water

When acidic water seeps through limestone and

some other minerals, it

dissolves some of the material and

takes it away.

Conservation of Mass

Law of conservation of mass:Mass is not created or destroyed in a

chemical reaction (mass is conserved)

Mass products = mass reactants

However, is mass conserved when a log burns in a fire??

By observing a burning log turn to ash, you may be tempted to think that during the chemical change that occurred, some mass was lost. It was not!!!

If you gathered all of the gases that formed, soot that was carried away, and water that evaporated out when the log was hot, you would find that there is exactly the same amount of mass after the log was burned as before the log was burned

Conservation of Mass Problems 68.5 grams of H2S contains 4.06 g of hydrogen

What mass of sulfur is in 68.5 grams of H2S?

What mass of hydrogen is in 200 grams of H2S?

What mass of sulfur is in 200 grams of H2S?