APES Chapter #3 Science, System, Matter and Energy

APES Chapter #3APES Chapter #3

Science, System, Matter Science, System, Matter and Energy and Energy

Nature of ScienceNature of Science

Science-Science- an organized way an organized way of using evidence to learn of using evidence to learn about the natural worldabout the natural world ObservationsObservations HypothesisHypothesis ExperimentExperiment ResultsResults ConclusionConclusion

Scientific MethodScientific MethodObservations and HypothesisObservations and Hypothesis

1.Observations/Questions1.Observations/Questions What you seeWhat you see Inferences-logical interpretations of Inferences-logical interpretations of

what you see.what you see. Questions then arise…….Questions then arise…….

2.Hypothesis2.Hypothesis-scientific and -scientific and testabletestable explanation for observationsexplanation for observations

““If……then……”If……then……”

Scientific MethodScientific MethodExperimental ProcedureExperimental Procedure

3.Experimental procedure-3.Experimental procedure- test the test the hypothesis hypothesis

Must be Must be controlledcontrolled, , reproduciblereproducible

Testing effects of Testing effects of only one variable only one variable (factor in experiment(factor in experimentthat is subject tothat is subject tochange)change)

Other scientists Other scientists need to be able to need to be able to reproduce and reproduce and prove valid.prove valid.

Scientific MethodScientific MethodExperimental ProcedureExperimental Procedure

Subjects you are testing are split into groups:Subjects you are testing are split into groups: Experimental GroupExperimental Group-given the experimental -given the experimental

factorfactor Control GroupControl Group:-what you’re comparing :-what you’re comparing

experimental group to.experimental group to.

Experimental GroupExperimental GroupFertilizerFertilizer

Control GroupControl GroupNo FertilizerNo Fertilizer

Scientific MethodScientific MethodExperimental ProcedureExperimental Procedure

Testing ONE variable while keeping Testing ONE variable while keeping others the sameothers the same Independent (manipulated) variableIndependent (manipulated) variable- -

factor in experiment that’s purposely factor in experiment that’s purposely changed—????changed—????

Dependent (responding) variableDependent (responding) variable —factor —factor that a scientist observes for responses that a scientist observes for responses (changes) in—????(changes) in—????

Scientific MethodScientific MethodResults and ConclusionResults and Conclusion

4. Results4. Results Record data—tables, graphsRecord data—tables, graphs Qualitative data-Qualitative data- physical traits ( physical traits (qualitqualities) ies)

describeddescribed Quantitative data-Quantitative data- measurements measurements

((quantitquantities) ies) 5.Conclusions5.Conclusions

Hypothesis is either supported or rejected. Hypothesis is either supported or rejected. NEVER “PROVEN!”NEVER “PROVEN!”

Can be partly trueCan be partly true Findings always useful!!!Findings always useful!!!

Scientific MethodScientific MethodHypothesis vs. TheoryHypothesis vs. Theory

Hypothesis-Hypothesis- educated, testable explanation for educated, testable explanation for an observationan observation

TheoryTheory Verified, credible and widely accepted Verified, credible and widely accepted

hypothesishypothesis Make future predictionsMake future predictions

Law-Law- mathematical description of what a theory mathematical description of what a theory explainsexplains

Models and Behavior of SystemsModels and Behavior of SystemsSystemSystem

Scientists determine the behavior of a system by Scientists determine the behavior of a system by developing a model of it in regards to matter and energydeveloping a model of it in regards to matter and energy

Set of components that function and interact in regular, Set of components that function and interact in regular, understandable wayunderstandable way

Inputs(from environment)

Throughputs(rates of flow)

Outputs(to environment)

Human Body(inputs may be stored for

different lengths of time)

Energy

Information

Matter

Heat

Ideas and

actionsWaste

and pollution

Models and Behavior of SystemsModels and Behavior of SystemsFeedback LoopsFeedback Loops

Feedback loops are found in a systemFeedback loops are found in a system Output fed back into system leads to changesOutput fed back into system leads to changes

Positive feedback-Positive feedback- AMPLIFICATION AMPLIFICATION i.e. global warmingi.e. global warming

Negative feedback-Negative feedback- CORRECTIVE CORRECTIVE System changes in opposite directionSystem changes in opposite direction i.e. thermostat in housei.e. thermostat in house crime and punishmentcrime and punishment

Models and Behavior of SystemsModels and Behavior of SystemsTime Delays and SynergyTime Delays and Synergy

Time delaysTime delays -delay b/t input and -delay b/t input and outputoutput Allows problems to build Allows problems to build

slowly so corrective action slowly so corrective action may come too latemay come too late

i.e. smoking and populationi.e. smoking and population SynergySynergy- 2 or more processes - 2 or more processes

interact so their combined effect interact so their combined effect is > than the sum of separate is > than the sum of separate effectseffects i.e. drugs and alcohol, i.e. drugs and alcohol,

people picking up objectpeople picking up object

MatterMatterAtomsAtoms

MatterMatter-anything that has mass and -anything that has mass and takes up spacetakes up space

AtomAtom--basic unit of matter--basic unit of matter Protons—positive, nucleusProtons—positive, nucleus Neutrons—neutral, nucleusNeutrons—neutral, nucleus Electrons—negative, orbitsElectrons—negative, orbits

MatterMatterParts of AtomsParts of Atoms

Protons and NeutronsProtons and Neutrons Together make up an atom’s Together make up an atom’s

atomic mass.atomic mass. ElectronsElectrons

1/1840 of the mass of p’s and n’s1/1840 of the mass of p’s and n’s Moving in orbitals surrounding Moving in orbitals surrounding

the nucleus the nucleus Responsible for chemical Responsible for chemical

properties of atoms (how they properties of atoms (how they react)react)

Atoms--Something to Think AboAtoms--Something to Think About!ut!

MatterMatterElementsElements

ElementElement-pure substance that consists of just one type of -pure substance that consists of just one type of atomatom

114 in the periodic table 114 in the periodic table Atoms have a one or two letter symbolAtoms have a one or two letter symbol Atomic numberAtomic number

Unique to that elementUnique to that element #p’s-- and b/c normally atoms #p’s-- and b/c normally atoms are uncharged also = # e’sare uncharged also = # e’s

Atomic massAtomic mass How much mass an atom hasHow much mass an atom has #p’s + #n’s#p’s + #n’s

CCarbon12.011

6

Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14

6 electrons6 protons6 neutrons

6 electrons6 protons8 neutrons

6 electrons6 protons7 neutrons

Isotopes of Carbon

6MatterMatterIsotopesIsotopes

IsotopesIsotopes-atoms of the same element with different # of -atoms of the same element with different # of neutronsneutronsAtomic number same, atomic mass differentAtomic number same, atomic mass different

MatterMatterRadioactive IsotopesRadioactive Isotopes

Radioactive isotopes-Radioactive isotopes- atoms with unstable atoms with unstable nucleinuclei Break down at constant rate and can Break down at constant rate and can

give off dangerous radiation (type of give off dangerous radiation (type of energy)energy)

Beneficial uses:Beneficial uses: C-14 dating can help geologists date C-14 dating can help geologists date

fossils fossils Cancer treatmentCancer treatment U-235 in nuclear reactorsU-235 in nuclear reactors

MatterMatterBondingBonding

Bonding-Bonding- atoms gain, lose, or share e’s to be stable atoms gain, lose, or share e’s to be stable CompoundCompound- formed by chemical combination of 2 or more - formed by chemical combination of 2 or more

elementselements Bond formation involves outermost e’s Bond formation involves outermost e’s Two types of bondsTwo types of bonds

IonicIonic CovalentCovalent

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transferof electron

Protons +11Electrons -11Charge 0

Protons +17Electrons -17Charge 0

Protons +11Electrons -10Charge +1

Protons +17Electrons -18Charge -1

Chemical BondsChemical Bonds Ionic bondsIonic bonds

•Ionic bondIonic bond -one or more e’ are transferred -one or more e’ are transferred •Results in formation of ions, or charged atoms that attract to Results in formation of ions, or charged atoms that attract to form an form an ionic compoundionic compound

Chemical BondsChemical BondsCovalent BondsCovalent Bonds

Covalent bonds- Covalent bonds- formed by atoms formed by atoms sharing valence electronssharing valence electrons Stronger than ionic bondsStronger than ionic bonds MoleculeMolecule--forms when atoms --forms when atoms

are joined in a covalent bondare joined in a covalent bond

CompoundsCompounds

Organic-Organic- contain C-C bonds contain C-C bonds Can also have H, O, P, S, N Can also have H, O, P, S, N

and othersand others Natural or synthetic Natural or synthetic InorganicInorganic- don’t have C-C or C-- don’t have C-C or C-

H covalent bondsH covalent bonds NaCl, HNaCl, H22OO

CC

Organic CompoundsOrganic Compounds

Some simple organic molecules can link up, forming C—C Some simple organic molecules can link up, forming C—C bonds- bonds- polymerizationpolymerization Amino acids Amino acids Proteins (meats, enzymes)Proteins (meats, enzymes) Fatty Acids and glycerol Fatty Acids and glycerol Lipids (fats, oils)Lipids (fats, oils) Sugars Sugars Carbohydrates (sugar, starches) Carbohydrates (sugar, starches) Nucleotides Nucleotides Nucleic acids (DNA or RNA) Nucleic acids (DNA or RNA)

Inorganic CompoundsInorganic Compounds No C-C bondsNo C-C bonds Earth’s crust is mostly Earth’s crust is mostly

inorganic minerals and rockinorganic minerals and rock Various combinations of only Various combinations of only

eight elements make up the eight elements make up the bulk of most minerals. bulk of most minerals.

Four States of MatterFour States of Matter Differ in spacing and orderliness of atoms, ions or Differ in spacing and orderliness of atoms, ions or

moleculesmolecules SolidSolid LiquidLiquid GasGas PlasmaPlasma

Most abundant of all states of matter!Most abundant of all states of matter! Forms when enough energy applied to strip away e’, Forms when enough energy applied to strip away e’,

so it’s a mixture of ions and e’so it’s a mixture of ions and e’ Natural forms: sun, stars, lightning and flame Natural forms: sun, stars, lightning and flame Artificial forms: TV, neon signsArtificial forms: TV, neon signs

Matter QualityMatter Quality

High qualityHigh quality Easily accessibleEasily accessible High concentrationHigh concentration Great potential for use as resourceGreat potential for use as resource

Low qualityLow quality Deep underground or difficult to Deep underground or difficult to

collectcollect Low concentrationLow concentration Low potential as a resourceLow potential as a resource

High Quality

Solid

Salt

Coal

Gasoline

Aluminum can

Low Quality

Gas

Solution of salt in water

Coal-fired powerplant emissions

Automobile emissions

Aluminum ore

Law of Conservation of MatterLaw of Conservation of Matter

Physical changesPhysical changes in matter in matter Molecules organized Molecules organized

differently but no change differently but no change in chemical compositionin chemical composition

Cutting foil, melting waterCutting foil, melting water Chemical changesChemical changes

Bonds made or brokenBonds made or broken Burning coal, rustingBurning coal, rusting

ChemicalChemical ChangesChanges

Reactant(s)

carbon + oxygen

C + O2CO2 + energy

carbon dioxide + energy

+ energy

Product(s)

black solid colorless gas colorless gas

C

O

OO OC

Law of Conservation of MatterLaw of Conservation of Matter Law of Conservation of Matter-Law of Conservation of Matter- physical or physical or

chemical changes can’t create or destroy the chemical changes can’t create or destroy the atoms involved. They’re just rearrangedatoms involved. They’re just rearranged

Chemical equations must be balancedChemical equations must be balanced No “away”!!!! -Law tells us there will always be No “away”!!!! -Law tells us there will always be

wastes, pollutants, and toxinswastes, pollutants, and toxins

ToxicologyToxicology

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ToxicologyToxicology -the study of the adverse effects of chemicals or -the study of the adverse effects of chemicals or pollutants on living organisms’ health, specifically humans.pollutants on living organisms’ health, specifically humans.

ToxicityToxicity -a measure of how harmful a substance is and it -a measure of how harmful a substance is and it depends on:depends on:

-Amount of a potentially harmful substance that is -Amount of a potentially harmful substance that is ingested, inhaled, or absorbed through the skin is called ingested, inhaled, or absorbed through the skin is called the the dosedose

-Frequency of exposure-Frequency of exposure-Who is exposed (adult or child)-Who is exposed (adult or child)-How well the body’s detoxification system (liver, kidneys, -How well the body’s detoxification system (liver, kidneys,

etc.) work etc.) work

The resulting type and amount of damage to health areThe resulting type and amount of damage to health arecalled the responsecalled the response

Two types of responses:Two types of responses: Acute-Acute- immediate or rapid harmful reaction immediate or rapid harmful reaction

(dizziness, rash, death)(dizziness, rash, death) Chronic-Chronic- permanent or long–lasting consequence permanent or long–lasting consequence

(asthma, kidney damage, heart disease)(asthma, kidney damage, heart disease)

ToxicologyToxicology

Six major characteristics of a substance determines its toxicity:Six major characteristics of a substance determines its toxicity: 1. Concentration1. Concentration

1ppm= 1 1ppm= 1 ppart pollutant art pollutant pper er mmillion parts of gas, solid or illion parts of gas, solid or liquid it is inliquid it is in

Can Can ↓ pollutant concentration by dumping in larger ↓ pollutant concentration by dumping in larger volume, but there are limitsvolume, but there are limits

2. Solubility2. Solubility Water-soluble- move through the environment and get in Water-soluble- move through the environment and get in

the water supplythe water supply Fat-soluble- penetrate cell membranes and accumulate Fat-soluble- penetrate cell membranes and accumulate

in body tissuein body tissue

Toxicology FactorsToxicology Factors

3. Persistence3. Persistence Some chemicals are resistant to breakdown so have Some chemicals are resistant to breakdown so have

long-lasting harmful effectslong-lasting harmful effects DegradableDegradable (nonpersistent)—broken down by natural, (nonpersistent)—broken down by natural,

physical, chemical or biological processesphysical, chemical or biological processes BiodegradableBiodegradable—broken down by living organisms—broken down by living organisms Slowly degradableSlowly degradable (persistent) (persistent)

Decades Decades Plastics, DDTPlastics, DDT

NondegradingNondegrading—lead, mercury, arsenic—lead, mercury, arsenic

Toxicology FactorsToxicology Factors

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• 4. Bioaccumulation4. Bioaccumulation results results when the concentration of a when the concentration of a chemical in tissues of an chemical in tissues of an organism is higher than organism is higher than would normally be expected.would normally be expected.

• 5. Biomagnification 5. Biomagnification involves magnification of involves magnification of concentrations as they pass concentrations as they pass through the food chains and through the food chains and webs.webs.

Toxicology FactorsToxicology Factors

6. Chemical Interactions6. Chemical Interactions Antagonistic interactions reduce harmful effectsAntagonistic interactions reduce harmful effects

Vitamin A, D and E apparently reduce some Vitamin A, D and E apparently reduce some cancer-causing chemicalscancer-causing chemicals

Synergistic interactions multiplies harmful effectsSynergistic interactions multiplies harmful effects Asbestos workers have a 20-fold increased Asbestos workers have a 20-fold increased

chance of getting lung cancer, but if they chance of getting lung cancer, but if they smoke they have a 400-fold increasesmoke they have a 400-fold increase

Toxicology FactorsToxicology Factors

Determining ToxicityDetermining Toxicity

Determining toxicity:Determining toxicity:

• Case reports (usually to physicians) Case reports (usually to physicians)

• Epidemiology- studies of populations exposed Epidemiology- studies of populations exposed

• Laboratory investigations (usually with test animals)Laboratory investigations (usually with test animals)

- LDLD5050 (median (median llethal ethal ddose)ose) -amt of a chemical that kills 50% -amt of a chemical that kills 50%

of animals (rats) in a test population (60–200 animals) in 2 of animals (rats) in a test population (60–200 animals) in 2 weeks weeks

- A A poisonpoison is legally defined as a chemical that has an is legally defined as a chemical that has an LDLD5050

≤≤50 mg chemical/kg body weight50 mg chemical/kg body weight

***Higher LD50, less toxic the substance is***Higher LD50, less toxic the substance is

ToxicityToxicityToxicityToxicity LDLD5050 Lethal DoseLethal Dose ExamplesExamples

Super Super < 0.01< 0.01 less than 1 drop less than 1 drop dioxin, botulismdioxin, botulismmushroomsmushrooms

Extreme Extreme <5<5 less than 7 drops less than 7 drops heroin, nicotineheroin, nicotine

Very Very 5-505-50 7 drops to 1 tsp. 7 drops to 1 tsp. morphine, codeinemorphine, codeine

ToxicToxic 50-50050-500 1 tsp. 1 tsp. DDT, H DDT, H22SOSO44, ,

CaffeineCaffeine

Moderate Moderate 500-5K500-5K 1 oz.-1 pt.1 oz.-1 pt. aspirin, wood aspirin, wood alcoholalcohol

SlightlySlightly 5K-15K 5K-15K 1 pt. 1 pt. ethyl alcohol, soapsethyl alcohol, soaps

Non-ToxicNon-Toxic >15K>15K >1qt.>1qt. water, table sugar water, table sugar***Higher LD50, less toxic the substance is***Higher LD50, less toxic the substance is

(LD50 measured in mg/kg of body weight)(LD50 measured in mg/kg of body weight)

Dose–Response CurvesDose–Response Curves

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Dose–response curves-Dose–response curves- show the adverse effects of show the adverse effects of various doses of a toxic agent on a test population by various doses of a toxic agent on a test population by plotting harmful effect as a function of dose.plotting harmful effect as a function of dose.

The left dose–The left dose–response curve response curve shows increasing shows increasing harmful effects with harmful effects with dose, and no dose dose, and no dose is considered safe. is considered safe.

The right example The right example has a threshold, has a threshold, such that low doses such that low doses are considered safe.are considered safe.

Why so little is known of toxicityWhy so little is known of toxicity Only 10% of at least 75,000 commercial chemicals have Only 10% of at least 75,000 commercial chemicals have

been screenedbeen screened ~2% determined to be carcinogen, teratogen or mutagen~2% determined to be carcinogen, teratogen or mutagen >1000 new synthetic chemicals added per year>1000 new synthetic chemicals added per year >99.5% of US commercial chemicals are NOT regulated>99.5% of US commercial chemicals are NOT regulated

ToxicityToxicity

Chemical HazardsChemical Hazards

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What are toxic vs. hazardous chemicals?What are toxic vs. hazardous chemicals?

• Toxic (poisonous) chemicals-Toxic (poisonous) chemicals- substances that are fatal substances that are fatal to over 50% of test animals (LDto over 50% of test animals (LD5050) at given ) at given

concentrationsconcentrations

• Hazardous chemicalsHazardous chemicals- cause harm by- cause harm by

- Flammable or explosive (e.g., gasoline)Flammable or explosive (e.g., gasoline)

- Irritating or damaging the skin or lungs (e.g., strong Irritating or damaging the skin or lungs (e.g., strong acids or alkalines such as oven cleaners)acids or alkalines such as oven cleaners)

- Interfering with or preventing oxygen uptake and Interfering with or preventing oxygen uptake and distribution (e.g., carbon monoxide, CO)distribution (e.g., carbon monoxide, CO)

- Inducing allergic reactions Inducing allergic reactions

Hazardous chemicalsHazardous chemicals

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• Mutagens-Mutagens- cause random mutations, or changes in the cause random mutations, or changes in the DNADNA

• Teratogens-Teratogens- cause birth defects cause birth defectse.g., PCBs, steroid hormones, heavy metals, rubella, e.g., PCBs, steroid hormones, heavy metals, rubella, mercury in water, fetal alcohol syndrome and crack mercury in water, fetal alcohol syndrome and crack babiesbabies

• Carcinogens-Carcinogens- cause cancer cause cancer- over 100 types of cancer (depending on cells involved)over 100 types of cancer (depending on cells involved)- e.g., cigarette smoke.e.g., cigarette smoke.

- Hormone disruptersHormone disrupters

Hormone DisruptersHormone Disrupters

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HormonesHormones -molecules that act -molecules that act as messengers in the as messengers in the endocrine system to regulate endocrine system to regulate reproduction, growth and reproduction, growth and development. development.

Hormone disrupters (mimics Hormone disrupters (mimics and blockers), attach to and blockers), attach to receptors and disrupt/alter receptors and disrupt/alter development.development.

Hormone DisruptersHormone Disrupters

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• 51 chemicals, many widely used, have been 51 chemicals, many widely used, have been shown to be hormone disrupters on wildlife, shown to be hormone disrupters on wildlife, laboratory animals and humanslaboratory animals and humans

- i.e. dioxins, certain PCBs, various chemicals in i.e. dioxins, certain PCBs, various chemicals in plastics, some pesticides, lead and mercuryplastics, some pesticides, lead and mercury

• 1997 study shows that sperm count of men in 1997 study shows that sperm count of men in U.S. and Europe has declined 50%.U.S. and Europe has declined 50%.

EnergyEnergy

EnergyEnergy- capacity to do work and - capacity to do work and transfer heattransfer heat

Measured in calories = amt of Measured in calories = amt of heat required to raise the temp of heat required to raise the temp of 1.0g of water 11.0g of water 1ooCC

Work is movement of matter Work is movement of matter (pump gas through pipe, move (pump gas through pipe, move book)book)

EnergyEnergy

Two typesTwo types KineticKinetic

Energy in motionEnergy in motion Possessed by matter b/c of its Possessed by matter b/c of its

mass and speed (velocity)mass and speed (velocity) PotentialPotential

Stored energyStored energy Potential to be changed into Potential to be changed into

kinetic energykinetic energy Rock in hand, unlit match, energy Rock in hand, unlit match, energy

stored in bonds of foodstuff, water stored in bonds of foodstuff, water behind dambehind dam

Sun

High energy, shortwavelength

Low energy, longwavelength

Ionizing radiation Nonionizing radiation

Cosmicrays

Gammarays

X rays Farultraviolet

waves

Nearultraviolet

waves

VisibleNear

infraredwaves

Farinfraredwaves

Microwaves TVwaves

Radiowaves

10-14 10-12 10-8 10-7 10-6 10-5 10-3 10-2 10-1 1

•Electromagnetic radiation (EM)-Electromagnetic radiation (EM)- energy traveling in waves as energy traveling in waves as a result of changing electric and magnetic fieldsa result of changing electric and magnetic fields•Different forms with different wavelengths and energy contentDifferent forms with different wavelengths and energy content•Electromagnetic Radiation Movie

EnergyEnergyElectromagnetic radiationElectromagnetic radiation

EnergyEnergyElectromagnetic radiationElectromagnetic radiation

Two types of EM radiationTwo types of EM radiation Ionizing EM radiationIonizing EM radiation

High energyHigh energyknock e’s from knock e’s from atoms and change them to + ionsatoms and change them to + ions

e’s and ions disrupt living cells-e’s and ions disrupt living cells-cancercancer

Non-ionizing EM radiationNon-ionizing EM radiation Low energy Low energy Not highly reactive Not highly reactive

or as dangerous.or as dangerous. Visible light-- makes up most of Visible light-- makes up most of

the spectrum of EM radiation the spectrum of EM radiation from the sun.from the sun.

EnergyEnergyHeatHeat

HeatHeat- total kinetic energy of all - total kinetic energy of all moving atoms, ions or moleculesmoving atoms, ions or molecules

TemperatureTemperature—average speed of —average speed of motion of the atoms, ions or motion of the atoms, ions or molecules in mattermolecules in matter

Atoms move faster when heatedAtoms move faster when heated Heat energy flows hot Heat energy flows hot cold cold Hot air/water less dense due to Hot air/water less dense due to

energy so rises.energy so rises.

Energy Energy QualityQuality

Energy quality-Energy quality- measure of energy source’s measure of energy source’s ability to do useful workability to do useful work High qualityHigh quality

ConcentratedConcentrated Can perform much useful workCan perform much useful work Chemical energy in coal and gas, Chemical energy in coal and gas,

sunlightsunlight Low qualityLow quality

DispersedDispersed Little ability to do workLittle ability to do work Heat in atmosphere or heat in oceansHeat in atmosphere or heat in oceans

Energy LawsEnergy Laws11stst Law of Thermodynamics Law of Thermodynamics

11stst law of thermodynamics law of thermodynamics (Law of conservation of (Law of conservation of energy) energy) In all physical and chemical changes, energy is not In all physical and chemical changes, energy is not

created or destroyed, but changes formcreated or destroyed, but changes form Total energy of system remains constantTotal energy of system remains constant

Energy LawsEnergy Laws22ndnd Law of Thermodynamics Law of Thermodynamics

22ndnd Law of Thermodynamics Law of Thermodynamics (Law of (Law of disorder)disorder) When energy changed from one form When energy changed from one form

to another, useful energy is degraded to another, useful energy is degraded to lower quality, more dispersed, less to lower quality, more dispersed, less useful energyuseful energy

Light bulb---95% lost as waste heatLight bulb---95% lost as waste heat Energy stored in food---most lost as Energy stored in food---most lost as

waste heatwaste heat **We can never recycle or reuse **We can never recycle or reuse

high-quality energy to perform useful high-quality energy to perform useful workwork

Solarenergy

Wasteheat

Chemicalenergy

(photosynthesis)

Wasteheat

Wasteheat

Wasteheat

Chemicalenergy(food)

Mechanicalenergy

(moving,thinking,

living)

Nuclear ChangesNuclear Changes

Matter can undergo physical, chemical OR nuclear Matter can undergo physical, chemical OR nuclear changeschanges

Nuclear change-Nuclear change--nucleus of certain isotopes -nucleus of certain isotopes spontaneously change or are made to change into nuclei spontaneously change or are made to change into nuclei of different isotopesof different isotopes

Matter Matter Energy Energy 3 types of nuclear change3 types of nuclear change

Radioactive decayRadioactive decay Nuclear fissionNuclear fission Nuclear fusionNuclear fusion

Nuclear ChangesNuclear ChangesRadioactive DecayRadioactive Decay

Radioactive isotopes with unstable nuclei decayRadioactive isotopes with unstable nuclei decay Particles and/or damaging ionizing radiation, emitted Particles and/or damaging ionizing radiation, emitted

until nuclei stable and not radioactiveuntil nuclei stable and not radioactive Gamma raysGamma rays Genetic damage to DNAGenetic damage to DNA Somatic damage to tissuesSomatic damage to tissues

Nuclear ChangesNuclear ChangesRadioactive DecayRadioactive Decay

Radioactive isotopes decay at Radioactive isotopes decay at a characteristic fixed rate a characteristic fixed rate called a called a half-life (thalf-life (t1/21/2)) Time for half the nuclei in a Time for half the nuclei in a

sample to decaysample to decay Can’t be changed due to T, Can’t be changed due to T,

P, or chemical rxnsP, or chemical rxns Used to estimate time a Used to estimate time a

sample of radioisotope sample of radioisotope must be stored safely must be stored safely before it decays to a safe before it decays to a safe level level half-life X 10half-life X 10

Table 3-1 Half-Lives of Selected Radioisotopes

Isotope

Potassium-42

Iodine-131

Cobalt-60

Hydrogen-3 (tritium)

Strontium-90

Carbon-14

Plutonium-239

Uranium-235

Uranium-238

Radiation Half-Life

12.4 hours

8 days

5.27 years

12.5 years

28 years

5,370 years

24,000 years

710 million years

4.5 billion years

Emitted

Alpha, beta

Beta, gamma

Beta, gamma

Beta

Beta

Beta

Alpha, gamma

Alpha, gamma

Alpha, gamma

Nuclear ChangesNuclear ChangesNuclear FissionNuclear Fission

FissionFission—splitting of nuclei—splitting of nuclei Nuclei of isotopes with large Nuclei of isotopes with large

masses split into lighter masses split into lighter nuclei when struck by nuclei when struck by neutronsneutrons

Release energy and more Release energy and more neutrons setting off a chain neutrons setting off a chain reactionreaction

Atomic bomb and nuclear Atomic bomb and nuclear power plants power plants

Fission fragment

Fission fragment

Energy

n n

n

n

Uranium-235nucleus

Unstablenucleus

Energy

n

U23592

9236 Kr

Ba14156

n

n

n

9236 Kr

U23592

U23592

Ba14156

9236

Kr

Ba14156

9236

Kr

Ba14156

n

n

n

n

n

n

n

n

U23592

U23592

U23592

U23592

n

Nuclear ChangesNuclear ChangesNuclear FusionNuclear Fusion

FusionFusion—joining of nuclei—joining of nuclei Isotopes of light elements are Isotopes of light elements are

forced together at high T’s until forced together at high T’s until they fuse into a heavier nucleusthey fuse into a heavier nucleus

Harder to accomplish than Harder to accomplish than fission, but releases more fission, but releases more energyenergy

Fusion of H nuclei to form He Fusion of H nuclei to form He nuclei is a source of energy for nuclei is a source of energy for sun and starssun and stars

H bombsH bombs

Fuel Reaction Conditions Products

D-T Fusion

Hydrogen-2 ordeuterium nucleus

Hydrogen-3 ortritium nucleus

+

+

Neutron

Energy

+ +

Helium-4nucleus

++

100 million ˚C

Neutron

Proton+

Matter and Energy LawsMatter and Energy LawsEnvironmental ProblemsEnvironmental Problems

Law of conservation of matter and 1Law of conservation of matter and 1stst and 2 and 2ndnd law of law of thermodynamics together mean individual resource use thermodynamics together mean individual resource use adds waste matter and heat to the environmentadds waste matter and heat to the environment

Different types of economic systemsDifferent types of economic systems High-throughput, high waste economiesHigh-throughput, high waste economies Matter-recycling-and-reuse economyMatter-recycling-and-reuse economy Low-throughput economyLow-throughput economy

Matter and Energy LawsMatter and Energy LawsEnvironmental ProblemsEnvironmental Problems

High-throughput EconomyHigh-throughput Economy Developed countries with ever increasing growthDeveloped countries with ever increasing growth Increased one-way flow of matter through systems and Increased one-way flow of matter through systems and

out to planetary “sinks”--air, water, soil, and organismsout to planetary “sinks”--air, water, soil, and organisms Pollutants and wastes accumulatePollutants and wastes accumulate Output will exceed environment’s capacity to dilute Output will exceed environment’s capacity to dilute

and degrade waste matter and absorb heatand degrade waste matter and absorb heat UNSUSTAINABLE!UNSUSTAINABLE!

Matter and Energy LawsMatter and Energy LawsEnvironmental ProblemsEnvironmental Problems

Low-Throughput EconomyLow-Throughput Economy Decrease matter and energy flowDecrease matter and energy flow Don’t waste matter and energy resourcesDon’t waste matter and energy resources Recycle and reuseRecycle and reuse Stabilize populationStabilize population