matter

MatterMatter

• Matter can be invisible. Air is matter, but it cannot be seen.

• Matter appears to be continuous and unbroken.

─ Matter is actually discontinuous. It is made up of tiny particles call atoms.

• Matter is anything that has mass and occupies space.

1.3

An apparently empty test tube is submerged, mouth downward in water. Only a small volume of water rises into the tube, which is actually filled with invisible matter–air.

Physical StatesPhysical Statesof Matterof Matter

Shape • Definite - does not change. It is independent of its container.

Volume • Definite

Particles • Particles are close together. Theycling rigidly to each other.

SOLIDS

Compressibility • Very slight–less than liquidsand gases.

Solid

Amorphous Solid Crystalline Solid

Particles lack a regularinternal arrangement

Particles exist in regular, repeating three-dimensional geometric patterns.

Glass, plastics, gels Diamond, metals, salts

A solid can be either crystalline or amorphous. Which one it is depends on the internal arrangement of the particles that constitute the solid.

Shape • Not definite - assumes the shape of its container.

Volume • Definite

Particles • Particles are close together.• Particles are held together by strong

attractive forces. They stick firmly but not rigidly to each other.

• They can move freely throughout the volume of the liquid.

LIQUIDS

Compressibility • Very slight–greater than solids,less than gases.

GASES

Shape • No fixed shape.

Volume • Indefinite.

Particles • Particles are far apart compared to liquids and solids.

• Particles move independently of each other.

GASES

Compressibility • The actual volume of the gas particles is small compared to the volume of space occupied by the gas.– Because of this a gas can be

compressed into a very small volume or expanded almost indefinitely.

• Attractive forces are strongest in a solid.– These give a solid rigidity.

ATTRACTIVE FORCES

Solid

Liquid • Attractive forces are weaker in liquids than in solids.– They are sufficiently strong so that a

liquid has a definite volume.

ATTRACTIVE FORCES

Gas • Attractive forces in a gas are extremely weak.

• Particles in the gaseous state have enough energy to overcome the weak attractive forces that hold them together in liquids or solids.– Because of this the gas particles move

almost independently of each other.

Classifying MatterClassifying Matter

Matter refers to all of the materials that make up the universe.

Substance

A particular kind of matter that has a fixed composition and distinct properties.

Examples

ammonia, water, and oxygen.

Homogeneous Matter

Matter that is uniform in appearance and with uniform properties throughout.

Examples

ice, soda, pure gold

Heterogeneous Matter

Matter with two or more physically distinct phases present.

Examples

ice and water, wood, blood

Homogeneous

Heterogeneous

Phase

A homogenous part of a system separated from other parts by physical boundaries.

Examples

In an ice water mixture, ice is the solid phase and water is the liquid phase.

Mixture

Matter containing 2 or more substances that are present in variable amounts. Mixtures are variable in composition. They can be homogeneous or heterogeneous.

Homogeneous Mixture (Solution)

A homogeneous mixture of 2 or more substances. It has one phase.

ExampleSugar and water. Before the sugar and water are mixed, each is a separate phase. After mixing the sugar is evenly dispersed throughout the volume of the water.

Example

Sugar and fine white sand. The amount of sugar relative to sand can be varied. The sugar and sand each retain their own properties.

Heterogeneous MixtureA heterogeneous mixture consists of 2 or more phases.

Example• Iron (II) sulfide (FeS) is 63.5% Fe and 36.5% S

by mass.

• Mixing iron and sulfur in these proportions does not form iron (II) sulfide. Two phases are present: a sulfur phase and an iron phase.

• If the mixture is heated strongly a chemical reaction occurs and iron (II) sulfide is formed.

• FeS is a compound of iron and sulfur and has none of the properties of iron or sulfur.

Heterogeneous MixtureA heterogeneous mixture consists of 2 or more phases.

solid phase2

liquid phase

solid phase1

Heterogeneous Mixture

Mixture of iron and sulfur

Compound of iron and sulfur

Formula Has no definite formula: consists of Fe and S.

FeS

Composition Contains Fe and S in any proportion by mass.

63.5% Fe and 36.5% S by mass.

Separation Fe and S can be separated by physical means.

Fe and S can be separated only by chemical change.

Heterogeneous Mixture of One Substance

A pure substance can exist as different phases in a heterogeneous system.

Example

Ice floating in water consists of two phases and one substance. Ice is one phase, and water is the other phase. The substance in both cases is the same.

1.6

Classification of matter: A pure substance is always homogeneous in composition, whereas a mixture always contains two or more substances and may be either homogeneous or heterogeneous.

ElementsElements

An element is a fundamental or elementary substance that cannot be broken down into simpler substances by chemical means.

• All known substances on Earth and probably the universe are formed by combinations of more than 100 elements.

• Each element has a number.– Beginning with hydrogen as 1, the

elements are numbered in order of increasing complexity.

• Most substances can be decomposed into two or more simpler substances.

– Water can be decomposed into hydrogen and oxygen.

– Table salt can be decomposed into sodium and chlorine.

• An element cannot be decomposed into a simpler substance.

ATOM• The smallest particle of an element that

can exist.

• The smallest unit of an element that can enter into a chemical reaction.

CompoundsCompounds

A compound is a distinct substance that contains two or more elements combined in a definite proportion by weight.

• Compounds can be decomposed chemically into simpler substances–that is, into simpler compounds or elements.

• Elements cannot be decomposed into simpler substances.

• Atoms of the elements that constitute a compound are always present in simple whole number ratios. They are never present as fractional parts.

There are two types of compounds: molecular and ionic.

Metals, Nonmetals and Metalloids

MetalsMetals

Most elements

are metals

• Metals are solid at room temperature.– Mercury is an exception. At room temperature it

is a liquid.

• Metals have high luster (they are shiny).

• Metals are good conductors of heat and electricity.

• Metals are malleable (they can be rolled or hammered into sheets).

physicalproperties of metals

Most elements

are metals

• Metals are ductile (they can be drawn into wires).

• Most metals have a high melting point.

• Metals have high densities

Examples of Metals

goldironlead

• Many metals readily combine with nonmetals to form ionic compounds. – They can combine with sulfur.

• Metals have little tendency to combine with each other to form compounds.

chlorine.– In nature, minerals are formed by combinations

of the more reactive metals with other elements.

Chemical Properties of Metals

oxygen.

– A few of the less reactive metals such as copper, silver and gold are found in the free state.

– Metals can mix with each other to form alloys.• Brass is a mixture of copper and zinc.• Bronze is a mixture of copper and tin.• Steel is a mixture of carbon and iron.

Chemical Properties of Metals

NonmetalsNonmetals

• Have relatively low melting points

• Have low densities.

• Poor conductors of heat and electricity

• At room temperature, carbon, phosphorous, sulfur, selenium, and iodine are solids.

Physical Properties of Nonmetals

• Lack luster (they are dull)

Solid

sulfur selenium

Physical State at Room Temperature

phosphorouscarbon

iodine

liquid

Physical State at Room Temperature

bromine

gas

Physical State at Room Temperature

helium, neon, argon, krypton, xenon, radon

nitrogen, oxygen

fluorine, chlorine

MetalloidsMetalloids

Metalloids have properties that are intermediate between metals and nonmetals

The Metalloids

1. boron

2. silicon

3. germanium

4. arsenic

5. antimony

6. tellurium

7. polonium

Metals are found to the left of the metalloidsNonmetals are found to the right of the metalloids.

Properties of Properties of SubstancesSubstances

Properties of Properties of SubstancesSubstances

• A property is a characteristic of a substance.

• Each substance has a set of properties that are characteristic of that substance and give it a unique identity.

Properties of a Substance

Physical PropertiesPhysical Properties

• The inherent characteristics of a substance that are determined without changing its composition.

• Examples:

taste color physical state melting point boiling point

• 2.4 times heavier than air

• color is yellowish-green

• odor is disagreeable

• melting point –101oC

• boiling point –34.6oC

Physical Properties of Chlorine

Chemical PropertiesChemical Properties

Describe the ability of a substance to form new substances, either by reaction with other substances or by decomposition.

• It will not burn in oxygen.

• It will support the combustion of certain other substances.

• It can be used as a bleaching agent.

• It can be used as a water disinfectant.

• It can combine with sodium to form sodium chloride.

Chemical Properties of Chlorine

Physical ChangesPhysical ChangesPhysical ChangesPhysical Changes

tearing of paper change of ice into water change of water into steam heating platinum wire

• Changes in physical properties (such as size, shape, and density) or changes in the state of matter without an accompanying change in composition.

• Examples:

Physical Changes

• No new substances are formed.

Chemical ChangesChemical ChangesChemical ChangesChemical Changes

In a chemical change new substances are formed that have different properties and composition from the original material.

Heating a copper wire in a Bunsen burner causes the copper to lose its original appearance and become a black material.

Formation of Copper(II) Oxide

Heating a copper wire in a Bunsen burner causes the copper to lose its original appearance and become a black material.

The black material is a new substance called copper(II) oxide.

Copper is 100% copper by mass.

Copper (II) oxide is: 79.94% copper by mass

20.1% oxygen by mass.

The formation of copper(II) oxide from copper and oxygen is a chemical change. The copper (II) oxide is a new substance with properties that are different from copper.

Formation of Copper(II) Oxide

Copper(II) oxide is made up of Cu2+ and O2-

4.2

Neither Cu nor O2 contains Cu2+ or O2-A chemical change has occurred.

Water is decomposed into hydrogen and oxygen by passing electricity through it.

Decomposition of Water

The composition and physical appearance of hydrogen and oxygen are different from water.The hydrogen explodes with a pop upon the addition of a burning splint.The oxygen causes the flame of a burning splint to intensify.

They are both colorless gases.But the burning splint is extinguished when placed into the water sample.

Chemical EquationsChemical Equations

Water decomposes into hydrogen and oxygen when electrolyzed.

reactant productsyields

Chemical symbols can be used to express chemical reactions

Water decomposes into hydrogen and oxygen when electrolyzed.

reactant yields

2H2O 2H2 O2

products

Copper plus oxygen yields copper(II) oxide.

yield productreactants

heat

Copper plus oxygen yields copper(II) oxide.

yield productreactants

heat

2Cu O2 2Cu2O

ConservationConservationof Massof Mass

ConservationConservationof Massof Mass

No change is observed in the total mass of the substances involved in a chemical change.

sodium + sulfur sodium sulfide

46.0 g 32.1 g 78.1 g

78.1 g product

mass productsmass products

78.1 g reactant →

mass reactantsmass reactants ==

EnergyEnergyEnergyEnergy

Energy is the capacity to do work

Types of Energy

• mechanical

• chemical

• electrical

• heat

• nuclear

• radiant

Potential Energy

Energy that an object possesses due to its relative position.

increasing potential energy

50 ft

20 ft

The potential energy of the ball increases with increasing height.

increasing potential energy

Potential Energy

Stored energy

• The heat released when gasoline burns is associated with a decrease in its chemical potential energy.

• The new substances formed by burning have less chemical potential energy than the gasoline and oxygen.

• Gasoline is a source of chemical potential energy.

Kinetic Energy

Energy matter possesses due to its motion.

Moving bodies possess kinetic energy.

• The flag waving in the wind.

Moving bodies possess kinetic energy.

• A bouncing ball.• The running man.

• The runner

Moving bodies possess kinetic energy.

• The soccer player.

Moving bodies possess kinetic energy.

HeatHeatHeatHeat

Heat• A form of energy associated with

small particles of matter.

Temperature • A measure of the intensity of heat, or of how hot or cold a system is.

Units of Heat EnergyUnits of Heat Energy

• The SI unit for heat energy is the joule (pronounced “jool”).

• Another unit is the calorie.

4.184 J = 1 cal

(exactly) 4.184 Joules = 1 calorie

This amount of heat energy will raise the temperature of 1 gram of water 1oC.

A form of energy associated with small particles of matter.

A measure of the intensity of heat, or of how hot or cold a system is.

An Example of the Difference Between Heat and

Temperature

Twice as much heat energy is required to raise the temperature of 200 g of water 10oC as compared to 100 g of water.

200 g water

20oC

A

100 g water

20oC

B

100 g water

30oC

200 g water

30oC

heat beakers 4184 J 8368 Jtemperaturerises 10oC

ConservationConservationof Energyof Energy

ConservationConservationof Energyof Energy

An energy transformation occurswhenever a chemical change occurs.

• If energy is absorbed during a chemical change, the products will have more chemical potential energy than the reactants.

• If energy is given off in a chemical change, the products will have less chemical potential energy than the reactants.

4.3

H2 + O2 have higher potential energy than H2O

energy is given offenergy is absorbed

Electrolysis of Water Burning of Hydrogen in Air

higher potential energy lower potential energy

Law of Conservation of Energy

Energy can be neither created nor destroyed, though it can be transformed from one form of energy to another form of energy.