Chapter 2Chapter 2

Science, Systems, Science, Systems, Matter, and EnergyMatter, and Energy

Chapter Overview QuestionsChapter Overview Questions

What is science, and what do scientists do?What is science, and what do scientists do? What are major components and behaviors What are major components and behaviors

of complex systems?of complex systems? What are the basic forms of matter, and what What are the basic forms of matter, and what

makes matter useful as a resource?makes matter useful as a resource? What types of changes can matter undergo What types of changes can matter undergo

and what scientific law governs matter?and what scientific law governs matter?

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

What are the major forms of energy, and What are the major forms of energy, and what makes energy useful as a resource?what makes energy useful as a resource?

What are two scientific laws governing What are two scientific laws governing changes of energy from one form to another?changes of energy from one form to another?

How are the scientific laws governing How are the scientific laws governing changes of matter and energy from one form changes of matter and energy from one form to another related to resource use, to another related to resource use, environmental degradation and environmental degradation and sustainability?sustainability?

Core Case Study: Core Case Study: Environmental Lesson from Easter Environmental Lesson from Easter

IslandIsland Thriving societyThriving society

15,000 people by 1400.15,000 people by 1400. Used resources faster Used resources faster

than could be renewedthan could be renewed By 1600 only a few By 1600 only a few

trees remained.trees remained. Civilization collapsedCivilization collapsed

By 1722 only several By 1722 only several hundred people left.hundred people left.

Figure 2-1Figure 2-1

THE NATURE OF SCIENCETHE NATURE OF SCIENCE

What do scientists do?What do scientists do? Collect data.Collect data. Form hypotheses.Form hypotheses. Develop theories, Develop theories,

models and laws about models and laws about how nature works.how nature works.

Figure 2-2Figure 2-2

Fig. 2-2, p. 29

Well-tested andaccepted patterns

in data becomescientific laws

Interpret data

Ask a question

Do experimentsand collect data

Formulate hypothesisto explain data

Do more experimentsto test hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Ask a question

Do experimentsand collect data

Formulate hypothesisto explain data

Do more experimentsto test hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Interpret data

Well-tested andaccepted patternsIn data becomescientific laws

Fig. 2-3, p. 30

Stepped Art

Scientific Theories and Laws: The Scientific Theories and Laws: The Most Important Results of ScienceMost Important Results of Science

Scientific TheoryScientific Theory Widely tested and Widely tested and

accepted accepted hypothesis.hypothesis.

Scientific LawScientific Law What we find What we find

happening over and happening over and over again in over again in nature.nature.

Figure 2-3Figure 2-3

Fig. 2-3, p. 30

Research results

Scientific paper

Peer review byexperts in field

Paperrejected

Paper accepted

Paper published inscientific journal

Research evaluatedby scientific community

Testing HypothesesTesting Hypotheses

Scientists test hypotheses using controlled Scientists test hypotheses using controlled experiments and constructing mathematical experiments and constructing mathematical models.models. VariablesVariables or or factorsfactors influence natural processes influence natural processes Single-variable experiments involve a control and Single-variable experiments involve a control and

an experimental group.an experimental group. Most environmental phenomena are Most environmental phenomena are

multivariablemultivariable and are hard to control in an and are hard to control in an experiment.experiment.• Models are used to analyze interactions of variables.Models are used to analyze interactions of variables.

Scientific Reasoning and CreativityScientific Reasoning and Creativity

Inductive reasoningInductive reasoning Involves using specific observations and Involves using specific observations and

measurements to arrive at a general conclusion measurements to arrive at a general conclusion or hypothesis.or hypothesis.

Bottom-up reasoning going from specific to Bottom-up reasoning going from specific to general.general.

Deductive reasoningDeductive reasoning Uses logic to arrive at a specific conclusion.Uses logic to arrive at a specific conclusion. Top-down approach that goes from general to Top-down approach that goes from general to

specific.specific.

Frontier Science, Sound Science, and Frontier Science, Sound Science, and Junk ScienceJunk Science

Frontier science has not been widely tested Frontier science has not been widely tested (starting point of peer-review).(starting point of peer-review).

Sound science consists of data, theories and Sound science consists of data, theories and laws that are widely accepted by experts.laws that are widely accepted by experts.

Junk science is presented as sound science Junk science is presented as sound science without going through the rigors of peer-without going through the rigors of peer-review.review.

Limitations of Environmental ScienceLimitations of Environmental Science

Inadequate data and scientific understanding Inadequate data and scientific understanding can limit and make some results can limit and make some results controversial.controversial. Scientific testing is based on disproving rather Scientific testing is based on disproving rather

than proving a hypothesis.than proving a hypothesis.• Based on statistical probabilities.Based on statistical probabilities.

MODELS AND BEHAVIOR OF MODELS AND BEHAVIOR OF SYSTEMSSYSTEMS

Usefulness of modelsUsefulness of models Complex systems are predicted by developing a Complex systems are predicted by developing a

model of its inputs, throughputs (flows), and model of its inputs, throughputs (flows), and outputs of matter, energy and information.outputs of matter, energy and information.

Models are simplifications of “real-life”.Models are simplifications of “real-life”. Models can be used to predict Models can be used to predict if-thenif-then scenarios. scenarios.

Feedback Loops: Feedback Loops: How Systems Respond to ChangeHow Systems Respond to Change

Outputs of matter, energy, or information fed Outputs of matter, energy, or information fed back into a system can cause the system to back into a system can cause the system to do do moremore or or lessless of what it was doing. of what it was doing. Positive feedback loop causes a system to Positive feedback loop causes a system to

change further in the same direction (e.g. change further in the same direction (e.g. erosion)erosion)

Negative (corrective) feedback loop causes a Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. system to change in the opposite direction (e.g. seeking shade from sun to reduce stress).seeking shade from sun to reduce stress).

Feedback Loops: Feedback Loops:

Negative feedback can take so long that a Negative feedback can take so long that a system reaches a threshold and changes.system reaches a threshold and changes. Prolonged delays may prevent a negative Prolonged delays may prevent a negative

feedback loop from occurring.feedback loop from occurring. Processes and feedbacks in a system can Processes and feedbacks in a system can

(synergistically) interact to amplify the results.(synergistically) interact to amplify the results. E.g. smoking exacerbates the effect of asbestos E.g. smoking exacerbates the effect of asbestos

exposure on lung cancer.exposure on lung cancer.

TYPES AND STRUCTURE OF TYPES AND STRUCTURE OF MATTERMATTER

Elements and CompoundsElements and Compounds Matter exists in chemical forms as elements and Matter exists in chemical forms as elements and

compounds.compounds.• Elements (represented on the periodic table) are the Elements (represented on the periodic table) are the

distinctive building blocks of matter.distinctive building blocks of matter.• Compounds: two or more different elements held Compounds: two or more different elements held

together in fixed proportions by chemical bonds.together in fixed proportions by chemical bonds.

AtomsAtoms

Figure 2-4Figure 2-4

Animation: Subatomic ParticlesAnimation: Subatomic Particles

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Animation: Atomic Number, Mass Animation: Atomic Number, Mass NumberNumber

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IonsIons

An ion is an atom or group of atoms with one An ion is an atom or group of atoms with one or more net positive or negative electrical or more net positive or negative electrical charges.charges.

The number of positive or negative charges The number of positive or negative charges on an ion is shown as a superscript after the on an ion is shown as a superscript after the symbol for an atom or group of atoms symbol for an atom or group of atoms Hydrogen ions (HHydrogen ions (H++), Hydroxide ions (OH), Hydroxide ions (OH--)) Sodium ions (NaSodium ions (Na++), Chloride ions (Cl), Chloride ions (Cl--))

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The pH (potential of Hydrogen) is the The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of concentration of hydrogen ions in one liter of solution.solution.

Figure 2-5Figure 2-5

Animation: pH ScaleAnimation: pH Scale

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Compounds and Chemical FormulasCompounds and Chemical Formulas

Chemical formulas are shorthand ways to Chemical formulas are shorthand ways to show the atoms and ions in a chemical show the atoms and ions in a chemical compound. compound. Combining Hydrogen ions (HCombining Hydrogen ions (H++) and Hydroxide ) and Hydroxide

ions (OHions (OH--) makes the compound H) makes the compound H22O O

(dihydrogen oxide, a.k.a. water).(dihydrogen oxide, a.k.a. water). Combining Sodium ions (NaCombining Sodium ions (Na++) and Chloride ions ) and Chloride ions

(Cl(Cl--) makes the compound NaCl (sodium chloride ) makes the compound NaCl (sodium chloride a.k.a. salt).a.k.a. salt).

Organic Compounds: Carbon RulesOrganic Compounds: Carbon Rules

Organic compounds contain carbon atoms Organic compounds contain carbon atoms combined with one another and with various combined with one another and with various other atoms such as Hother atoms such as H++, N, N++, or Cl, or Cl--..

Contain at least two carbon atoms combined Contain at least two carbon atoms combined with each other and with atoms.with each other and with atoms. Methane (CHMethane (CH44) is the only exception.) is the only exception. All other compounds are All other compounds are inorganicinorganic..

Animation: Carbon BondsAnimation: Carbon Bonds

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Organic Compounds: Carbon RulesOrganic Compounds: Carbon Rules

HydrocarbonsHydrocarbons: compounds of carbon and : compounds of carbon and hydrogen atoms (e.g. methane (CHhydrogen atoms (e.g. methane (CH44)).)).

Chlorinated hydrocarbonsChlorinated hydrocarbons: compounds of : compounds of carbon, hydrogen, and chlorine atoms (e.g. carbon, hydrogen, and chlorine atoms (e.g. DDT (CDDT (C1414HH99ClCl55)).)).

Simple carbohydratesSimple carbohydrates: certain types of : certain types of compounds of carbon, hydrogen, and oxygen compounds of carbon, hydrogen, and oxygen (e.g. glucose (C(e.g. glucose (C66HH1212OO66)).)).

Cells: The Fundamental Units of LifeCells: The Fundamental Units of Life

Cells are the basic Cells are the basic structural and structural and functional units of all functional units of all forms of life.forms of life. Prokaryotic cells Prokaryotic cells

(bacteria) lack a distinct (bacteria) lack a distinct nucleus.nucleus.

Eukaryotic cells (plants Eukaryotic cells (plants and animals) have a and animals) have a distinct nucleus.distinct nucleus.

Figure 2-6Figure 2-6

Fig. 2-6a, p. 37

(a) Prokaryotic Cell

Protein constructionand energy conversionoccur without specializedinternal structures

Cell membrane(transport ofraw materials and finished products)

DNA(information storage, no nucleus)

Fig. 2-6b, p. 37

Protein construction

(b) Eukaryotic Cell

Cell membrane(transport of rawmaterials andfinished products)Packaging

Energy conversion

Nucleus (informationstorage)

Animation: Prokaryotic and Eukaryotic Animation: Prokaryotic and Eukaryotic CellsCells

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Macromolecules, DNA, Genes and Macromolecules, DNA, Genes and ChromosomesChromosomes Large, complex organic Large, complex organic

molecules (macromolecules) molecules (macromolecules) make up the basic molecular make up the basic molecular units found in living units found in living organisms.organisms. Complex carbohydratesComplex carbohydrates ProteinsProteins Nucleic acidsNucleic acids LipidsLipids

Figure 2-7Figure 2-7

Fig. 2-7, p. 38

The genes in each cell are coded by sequences of nucleotides in their DNA molecules.

A human body contains trillions of cells, each with an identical set of genes.

There is a nucleus inside each human cell (except red blood cells).

Each cell nucleus has an identical set of chromosomes, which are found in pairs.

A specific pair of chromosomes contains one chromosome from each parent.

Each chromosome contains a long DNA molecule in the form of a coiled double helix.

Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life.

Fig. 2-7, p. 38

A human body contains trillionsof cells, each with an identicalset of genes.

There is a nucleus inside eachhuman cell (except red blood cells).

Each cell nucleus has an identicalset of chromosomes, which arefound in pairs.

A specific pair of chromosomescontains one chromosome fromeach parent.

Each chromosome contains a longDNA molecule in the form of a coileddouble helix.

Genes are segments of DNA onchromosomes that contain instructionsto make proteins—the building blocksof life.

The genes in each cell are codedby sequences of nucleotides intheir DNA molecules.

Stepped Art

States of MatterStates of Matter

The atoms, ions, and molecules that make up The atoms, ions, and molecules that make up matter are found in three physical states:matter are found in three physical states: solid, liquid, gaseous.solid, liquid, gaseous.

A fourth state, plasma, is a high energy A fourth state, plasma, is a high energy mixture of positively charged ions and mixture of positively charged ions and negatively charged electrons.negatively charged electrons. The sun and stars consist mostly of plasma.The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in Scientists have made artificial plasma (used in

TV screens, gas discharge lasers, florescent TV screens, gas discharge lasers, florescent light).light).

Matter QualityMatter Quality

Matter can be classified Matter can be classified as having high or low as having high or low quality depending on quality depending on how useful it is to us as how useful it is to us as a resource.a resource. High quality matter is High quality matter is

concentrated and easily concentrated and easily extracted.extracted.

low quality matter is more low quality matter is more widely dispersed and widely dispersed and more difficult to extract.more difficult to extract.

Figure 2-8Figure 2-8

Fig. 2-8, p. 39

High Quality Low Quality

Salt

Solid Gas

Coal Coal-fired power plant emissions

GasolineAutomobile emissions

Solution of salt in water

Aluminum oreAluminum can

CHANGES IN MATTERCHANGES IN MATTER Matter can change from one physical form to Matter can change from one physical form to

another or change its chemical composition.another or change its chemical composition. When a physical or chemical change occurs, no When a physical or chemical change occurs, no

atoms are created or destroyed.atoms are created or destroyed.• Law of conservation of matter.Law of conservation of matter.

Physical change maintains original chemical Physical change maintains original chemical composition.composition.

Chemical change involves a chemical reaction Chemical change involves a chemical reaction which changes the arrangement of the elements which changes the arrangement of the elements or compounds involved.or compounds involved.• Chemical equations are used to represent the Chemical equations are used to represent the

reaction.reaction.

Chemical ChangeChemical Change

Energy is given off during the reaction as a product.Energy is given off during the reaction as a product.

p. 39

Reactant(s) Product(s)

carbon + oxygen carbon dioxide + energy

C + O2 CO2 energy+

energy+

black solid colorless gas colorless gas

+

Types of PollutantsTypes of Pollutants

Factors that determine the severity of a Factors that determine the severity of a pollutant’s effects: pollutant’s effects: chemical naturechemical nature, , concentrationconcentration, and , and persistencepersistence..

Pollutants are classified based on their Pollutants are classified based on their persistence:persistence: Degradable pollutantsDegradable pollutants Biodegradable pollutantsBiodegradable pollutants Slowly degradable pollutantsSlowly degradable pollutants Nondegradable pollutantsNondegradable pollutants

Nuclear Changes: Radioactive DecayNuclear Changes: Radioactive Decay

Natural radioactive decay: unstable isotopes Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of spontaneously emit fast moving chunks of matter (matter (alphaalpha oror beta particlesbeta particles), high-energy ), high-energy radiation (radiation (gamma raysgamma rays), or both at a fixed ), or both at a fixed rate.rate. Radiation is commonly used in energy production Radiation is commonly used in energy production

and medical applications.and medical applications. The rate of decay is expressed as a The rate of decay is expressed as a half-lifehalf-life (the (the

time needed for one-half of the nuclei to decay to time needed for one-half of the nuclei to decay to form a different isotope).form a different isotope).

Nuclear Changes: FissionNuclear Changes: Fission

Nuclear fission: Nuclear fission: nuclei of certain nuclei of certain isotopes with large isotopes with large mass numbers are mass numbers are split apart into split apart into lighter nuclei when lighter nuclei when struck by neutrons.struck by neutrons.

Figure 2-9Figure 2-9

Fig. 2-9, p. 41

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Neutron

FissionFragment

FissionFragment

Energy

EnergyEnergy

Energy

n

n

n

n

n

n

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235 Fig. 2-6, p. 28

Neutron

Uranium-235

Energy

Fissionfragment

Fissionfragment

n

n

n

n

n

n

Energy

Energy

Energy

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Nuclear Changes: FusionNuclear Changes: Fusion

Nuclear fusion: two isotopes of light elements Nuclear fusion: two isotopes of light elements are forced together at extremely high are forced together at extremely high temperatures until they fuse to form a heavier temperatures until they fuse to form a heavier nucleus.nucleus.

Figure 2-10Figure 2-10

Fig. 2-10, p. 42

Neutron

+

Hydrogen-2(deuterium nucleus)

Hydrogen-3(tritium nucleus)

+

Proton Neutron

100million °C

Energy

+

Helium-4 nucleus

ProductsReaction

ConditionsFuel

+

ENERGYENERGY

Energy is the ability to do work and transfer Energy is the ability to do work and transfer heat.heat. Kinetic energy – energy in motionKinetic energy – energy in motion

• heat, electromagnetic radiationheat, electromagnetic radiation Potential energy – stored for possible usePotential energy – stored for possible use

• batteries, glucose moleculesbatteries, glucose molecules

Electromagnetic SpectrumElectromagnetic Spectrum

Many different forms of electromagnetic Many different forms of electromagnetic radiation exist, each having a different radiation exist, each having a different wavelength and energy content.wavelength and energy content.

Figure 2-11Figure 2-11

Fig. 2-11, p. 43

Sun

Nonionizing radiationIonizing radiation

High energy, shortWavelength

Wavelength in meters(not to scale)

Low energy, longWavelength

Cosmicrays

GammaRays

X raysFar

infrared waves

Nearultra-violetwaves

VisibleWaves

Nearinfraredwaves

Farultra-violetwaves

Micro-waves

TVwaves

RadioWaves

Electromagnetic SpectrumElectromagnetic Spectrum

Organisms vary Organisms vary in their ability to in their ability to sense different sense different parts of the parts of the spectrum.spectrum.

Figure 2-12Figure 2-12

Fig. 2-12, p. 43

En

erg

y em

itte

d f

rom

su

n (

kcal

/cm

2 /m

in)

Wavelength (micrometers)

Ult

ravi

ole

t

Visible

Infrared

Animation: Visible LightAnimation: Visible Light

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Fig. 2-13, p. 44

Low-temperature heat (100°C or less) for space heating

Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing

steam, electricity, and hot water

Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors)

Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity

Dispersed geothermal energyLow-temperature heat (100°C or lower)

Normal sunlightModerate-velocity windHigh-velocity water flowConcentrated geothermal energyModerate-temperature heat

(100–1,000°C)Wood and crop wastes

High-temperature heat (1,000–2,500°C)Hydrogen gasNatural gasGasolineCoalFood

ElectricityVery high temperature heat (greater than 2,500°C)Nuclear fission (uranium)Nuclear fusion (deuterium)Concentrated sunlightHigh-velocity wind

Source of Energy RelativeEnergy Quality

(usefulness)

Energy Tasks

ENERGY LAWS: TWO RULES WE ENERGY LAWS: TWO RULES WE CANNOT BREAKCANNOT BREAK

The first law of thermodynamics: we cannot The first law of thermodynamics: we cannot create or destroy energy.create or destroy energy. We can change energy from one form to another.We can change energy from one form to another.

The second law of thermodynamics: energy The second law of thermodynamics: energy quality always decreases.quality always decreases. When energy changes from one form to another, When energy changes from one form to another,

it is always degraded to a more dispersed form.it is always degraded to a more dispersed form. Energy efficiency is a measure of how much Energy efficiency is a measure of how much

useful work is accomplished before it changes to useful work is accomplished before it changes to its next form.its next form.

Animation: Total Energy Remains Animation: Total Energy Remains ConstantConstant

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Fig. 2-14, p. 45

Chemicalenergy(food)

Solarenergy

WasteHeat

WasteHeat

WasteHeat

WasteHeat

Mechanicalenergy

(moving,thinking,

living)

Chemical energy

(photosynthesis)

Animation: Energy FlowAnimation: Energy Flow

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SUSTAINABILITY AND MATTER SUSTAINABILITY AND MATTER AND ENERGY LAWSAND ENERGY LAWS

Unsustainable High-Throughput Economies: Unsustainable High-Throughput Economies: Working in Straight LinesWorking in Straight Lines Converts resources to goods in a manner that Converts resources to goods in a manner that

promotes waste and pollution.promotes waste and pollution.

Figure 2-15Figure 2-15

Fig. 2-15, p. 46

High-quality energy

Matter

Unsustainablehigh-waste

economy

SystemThroughputs

Inputs(from environment)

Outputs(into environment)

Low-quality energy (heat)

Waste and pollution

Sustainable Low-Throughput Sustainable Low-Throughput Economies: Learning from NatureEconomies: Learning from Nature

Matter-Recycling-and-Reuse Economies: Matter-Recycling-and-Reuse Economies: Working in CirclesWorking in Circles Mimics nature by recycling and reusing, thus Mimics nature by recycling and reusing, thus

reducing pollutants and waste.reducing pollutants and waste. It is not sustainable for growing populations.It is not sustainable for growing populations.

Fig. 2-16, p. 47

Recycleand

reuse

Low-quality Energy(heat)

Waste and

pollution

Pollutioncontrol

Sustainable low-waste economy

Waste and

pollution

Matter Feedback

Energy Feedback

Inputs (from environment)

Energyconservation

Matter

Energy

SystemThroughputs

Outputs(into environment)

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