Science,Matter,Andenergy

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CHAPTER2

SCIENCE,MATTER,ANDENERGY

Outline

2-1Whatdoscientistsdo?

Scienceisasearchfororderinnature.
Science is an attempt to discover how nature works.
Scientists use this knowledge to make predictions about future events in nature..
Scientists use observations, experiments, and models to answer questions about how nature works.
The scientific process uses these steps:
Identify a problem.
Find out what is known about the problem.
Ask a question to investigate.
Perform an experiment and collect and analyze data to answer the question.
Propose an hypothesis to explain the .
Use the thesis to make testable predictions.
Test the predictions.
Accept or revise hypothesis.
Develop a scientific theory, if scientific hypothesis is well-tested and widely accepted.
Scientists are curious and skeptical, and demand lots of evidence.
Importantfeaturesofthescientificprocessareskepticism,reproducibility,andpeerreview.
Critical thinking and creativity are important in science
Critical thinking involves four important steps.
Be skeptical about everything you read or hear.
Look at the evidence and evaluate it and any related information.
Be open to many viewpoints and evaluate each one before coming to a conclusion.
Identify and evaluate your personal assumptions, biases, and beliefs.
Imagination, creativity and intuition are also important tools in science.
Scientifictheoriesandlawsarethemostimportantandcertainresultsofscience.
The goal of scientists is to develop theories and laws based on facts and data that explain how the physical world works.
A scientific theory has been tested widely, is supported by extensive evidence, and is accepted as being a useful explanation of some phenomenon by most scientists in a particular field or related fields of study.
A scientificlawis a well-tested and widely accepted description ofevents or actionsofnaturethat we find happening repeatedly in the same way.
Scientific laws cannot be broken except by discovering new data that lead to changes in the law.
Theresultsofsciencecanbetentative,reliable,orunreliable.
Resultsthathavenotbeenwidelytestedorarenotwidelyacceptedcan be calledtentativeor frontier science.Atthisstage,disagreementamongscientistsiscommonandleadstoadvancement.
Reliablescienceconsists of data, hypotheses, models, theories, and laws that are widely accepted by all or most of the scientists who are considered experts in the field under study.
Unreliablescienceincludesresultsthathavenotbeenrigorouslypeerreviewedorthathavebeendiscardedasaresultofpeerreview.
Questions to ask to determine if scientific findings are reliable or unreliable include:
Was the experiment well designed? Did it involve a control group
Have other scientists reproduced the results?
Does the proposed hypothesis explain the data? Have scientists made and verified projections based on the hypothesis?
Are there no other, more reasonable explanations of the data?
Are the investigators unbiased in their interpretations of the results? Were all the investigators’ funding sources unbiased?
Have the data and conclusions been subjected to peer review?
Are the conclusions of the research widely accepted by other experts in this field?
If “yes” is the answer to each of these questions, then the results can be called reliable science. Otherwise, the results may represent tentative science that needs further testing and evaluation, or you can classify them as unreliable science.
Sciencehassomelimitations.
Scientistscannot prove or disproveanything absolutelybecauseofinherentuncertaintyinmeasurements,observations,andmodels.
Scientistsattempttoestablishhighprobabilityor certainty of being useful for understanding some aspect of nature.
Beinghuman,scientistsarenotfreeofbias.
The peer review process helps to reduce personal bias.
Becausethenaturalworldissocomplex,therearemanyvariablesthatcannotbetested one at a time in controlled experiments.
Scientists use mathematical models that can take into account the interaction of many variables.

2-2What ismatterandwhat happens when it undergoes change?

Matterconsistsofelementsandcompounds.
Matterisanythingthathasmassandtakesupspace,livingornot.
Matterexistsinthreephysicalstates:solid,liquid,gas.
Matter exists in two chemical forms, elements and compounds.
Anelementisafundamentalsubstancethathasauniquesetofpropertiesandcannotbebrokendownintosimplersubstancesbychemicalmeans.
Elementsarerepresentedbyaone-ortwo-lettersymbol.
Compoundsarecombinationsoftwoormoredifferentelementsboundinfixedproportions.
Atoms,ions,andmoleculesarethebuildingblocksofmatter.
Anatomisthesmallestunitofmatterthatexhibitsthecharacteristicsofanelement.
Eachatomconsistsofsubatomicparticles: positivelychargedprotons,unchargedneutrons,andnegativelychargedelectrons.
Eachatomcontainsasmall center called the nucleus that contains protonsandneutrons.
Eachelementhasa uniqueatomicnumberthatisequaltothenumberofprotonsinthenucleusofitsatom.
Themassnumberofanatomisthetotalnumberofneutronsandprotonsinitsnucleus.
Isotopesareformsofanelementthathavethesameatomicnumber,butdifferentmassnumbers.
A molecule is a combination of two or more atoms of the same or different elements held together by chemical bonds
Anionisanatom or group of atoms with one or more net positive or negative charges.
pHisameasureofaciditybasedontheamountofhydrogenions(H+)andhydroxideions(OH-) in a solution.
A neutral solution has a pH of 7. A pH below 7 is an acidic solution, or acid. A pH above 7 is a basic solution, or base..
Chemicalformulasareatypeofshorthandtoshowthetypeandnumberofatoms/ionsinacompoundormolecule.

a.Eachelementinthecompoundisrepresentedbyasymbol(e.g.,H=hydrogen,O=oxygen).

b.Subscriptsshowthenumberofatoms/ionsinthecompound (e.g. H2O, or water, has two hydrogen atom and one oxygen atom). No subscript is used if there if only one atom of an element.

Organiccompoundsarethechemicalsoflife.
Organiccompoundscontainatleasttwocarbonatomscombinedwithvariousotheratoms. Methane(CH4)is an exception; it is considered an organic compound although ithas only one carbon atom.
All other compounds are called inorganic compounds.
Types of organic compounds include:
Hydrocarbons:compoundsofcarbonandhydrogenatoms.
Chlorinatedhydrocarbons:compoundsofcarbon,hydrogen,andchlorineatoms.
Simplecarbohydrates:specifictypesofcompoundsofcarbon,hydrogen,andoxygenatoms.
Macromolecules are large organic molecules. Many are polymers, large molecules made of smaller subunits called monomers joined together.
The major types of organic molecules are:
Complexcarbohydrates:twoormoremonomersofsimplesugarssuchasglucose
Proteins:formedbymonomerscalledaminoacids
Nucleicacids:(DNAandRNA)formedbymonomerscallednucleotides
Lipids, which include fats and waxes, and are not always made of monomers.
Mattercomes to lifethroughgenes,chromosomes,andcells.
All living organisms are made of cells.
Cellsarethesmallestandmostfundamentalstructuralandfunctionalunitsoflife.
DNAcontainssequencesofnucleotidesthatformgenesthatcodefortraits.
Thousands of genes make up chromosomes, which are composedofDNAandproteins.
Someformsofmatteraremoreusefulthanothers.
High-qualitymatterishighlyconcentrated,istypicallyfoundneartheearth’ssurface,andhasgreatpotentialforuseasaresource.
Low-qualitymatterisnothighlyconcentrated,isoftenlocateddeepundergroundordispersedintheoceanoratmosphere,andusuallyhaslittlepotentialforuseasaresource.
Matterundergoesphysical,chemical,andnuclearchanges.
Physicalchangeisnotchemicalcompositionchangebutachangeinstates, such as ice melting or water freezing.
Chemicalchangeorchemicalreactionisachangeinthechemicalcomposition.
We cannot createordestroy atoms: the Law of Conservation of Matter.
Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed.

2-3Whatisenergyandhowdophysicalandchemicalchangesaffectit?

Energycomesinmanyforms.
Energyisthecapacitytodoworkortransferheat.
Kineticenergyisenergyassociatedwithmotion.
Wind and flowing water are examples of kinetic energy.
Heat is a form of kinetic energy. When two objects at different temperatures contact one another heat flows from the warmer to the cooler object.
Electromagnetic radiation is a form of kinetic energy and occurs when energy travels as waves as a result of changes in electrical and magnetic fields.
Potentialenergyisstoredenergy.
Examples include water stored behind a dam and the chemical bonds in gasoline.
Potential energy can be changed to kinetic energy.
Examples include releasing water from behind a dam and burning gasoline in a car
Solar energy is major source of renewable energy.
It provides about 99% of the energy that heats the earth and provides us with food (through photosynthesis by plants).
Indirect forms of renewable solar energy include wind, hydropower and biomass.
Non-renewable fossil fuels provide the other 1% of the energy we use.
Sometypesofenergyaremoreusefulthanothers.
High-qualityenergyisconcentratedandhasahighcapacitytodousefulwork.
Low-qualityenergyisdispersedandhaslittlecapacitytodousefulwork.
Energychangesaregovernedbytwoscientificlaws.
Thefirst law of thermodynamics, or the lawofconservationofenergy,statesthatwhenenergyisconvertedfromoneformtoanotherinaphysicalorchemicalchange,noenergyiscreatedordestroyed.
Thesecondlawofthermodynamicsstatesthatwhenenergyischangedfromoneformtoanother,energyqualityisdepleted.
Three scientific laws govern what we can and cannot do with matter and energy

a.Thereisno“away.”

b.Youcannotgetsomethingfornothing.

c.Youcannotbreakeven.

Objectives

2-1Whatdoscientistsdo?

CONCEPT2-1Scientistscollectdataanddeveloptheories,models,andlawsabouthownatureworks.

Brieflydescribehowscienceworks.Statethequestionsthat sciencetriestoanswer.Summarizescientificmethods.
Statetheimportanceofcuriosity,skepticism,peerreview,critical thinking andcreativityinthescientificprocess.
Define scientific hypothesis, theory and scientific law or law of nature.
Describe the differences among frontier science, reliable science and unreliable science.

2-2What is matter and what happens when it undergoes change?

CONCEPT2-2AMatterconsistsofelementsandcompounds,whichinturnaremadeupofatoms,ions,ormolecules.

CONCEPT 2-2B Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

Definematter.Distinguishbetweenhigh- and low-qualityofmatter.
Define matter, elements, compounds and molecules. Describe the atomic theory and the sub-atomic particles and structure of an atom.
Describe pH and its importance.
Distinguish between organic and inorganic compounds.
Describe cells, genes and chromosomes.
Distinguishamongphysical,chemical,andnuclearchanges.
Statethelawofconservationofmatter.

2-3What is energy and what happens when it undergoes change?

CONCEPT2-3AWheneverenergyisconvertedfromoneformtoanotherinaphysicalorchemicalchange,noenergyiscreatedordestroyed(firstlawofthermodynamics).

CONCEPT 2-3B Whenever energy is converted from one form to another in a physical or chemical change, we end up with lower quality or less usable energy than we started with (second law of thermodynamics).

Defineenergy.Distinguishamongformsofenergyandbetween high- and low-qualityenergy.
State thefirstandsecondlawsofenergyandgiveanexampleofeach.
Describetheimplicationsofthelawsofmatterandenergyforalong-termsustainable-Earthsociety.
Describe the chapter’s three big ideas.

KeyTerms

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acidity(p.31)

atom(p.30)

atomicnumber(p.30)

atomictheory(p.30)

cells(p.32)

chemicalchange(p.33)

chemicalformula(p.32)

chemicalreaction(p.33)

chromosomes(p.32)

compounds(p.30)

data(p.27)

electromagneticradiation(p.35)

electrons(p.30)

elements(p.30)

energy(p.35)

energyquality(p.36)

firstlawof
thermodynamics(p.36)

fossil fuels (p. 36)

frontierscience(p.29)

genes(p.32)

heat(p.35)

high-qualityenergy(p.36)

high-qualitymatter(p.33)

inorganiccompounds(p.32)

ion(p.31)

isotopes(p.31)

kineticenergy(p.35)

lawofconservationof
energy(p.36)

lawofconservationof
matter(p.34)

low-qualityenergy(p.36)

low-qualitymatter(p.33)

massnumber(p.31)

matter(p.30)

matterquality(p.33)

model(p.27)

molecule(p.31)

neutrons(p.30)

nuclear change (p. 34)

nucleus(p.30)

organiccompounds(p.32)

peerreview(p.28)

pH(p.31)

physicalchange(p.33)

potentialenergy(p.35)

protons(p.30)

radioactive decay (p. 34)

reliablescience(p.29)

science(p.26)

scientifichypothesis(p.27)

scientificlaw(p.28)

scientifictheory(p.27)

secondlawofthermodynamics(p.36)

tentativescience(p.29)

trait(p.32)

unreliablescience(p.29)

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TeachingTips

Askthestudentstodescribewhatscientists“do,”orhowscientistsexpandourknowledgebase.Leadthediscussiontocontrolledexperiments,namelyhowscientistsdevelopexperimentsandtesthypotheses.Usethediscussionofcontrolledexperimentstointroducethecorecasestudy,HubbardBrook.

Usethecorestudytosolidifythestudents’understandingofcontrolgroup,experimentalgroup,andbaselinedata.Here,BormanandLikensperformthedauntingtaskofconductingacontrolledexperimentinthefield.Therefore,laboratoryandfieldexperimentscanbecompared.
Manystudentshavelittlenotionofhowscienceis“done.”Considerabletimeshouldbespentdiscussingwhatscienceis,includingthescientificmethod,itsuses,andlimitations.
Astheunderpinningofalltopicsdiscussedinthecourse/book,thetopicsofmatter,energy,andenergyuseshouldbeemphasized.

Askthestudentstoselectascientist(youcanhaveindexcardswithscientists(name,dates,location,scientificachievements)ortheycanresearchthescientistontheirown.Askthestudentstopretendtheyarethatscientist,andhavetheclasstrytoguesswhoeachstudentrepresents.

Bringinproductsmadeofmaterialsfoundontheperiodictable(jewelryworkswell).Foodorplantsworkwellfororganic(carbon-containing)examples,whileseasaltworkswellforinorganicexamples.

Inclearglasses,placesugarincoldwaterandhotwater(heatenergy)toshowdifferentratesofdissolving,thenstir(mechanicalenergy).

Show examples of potential versus kinetic energy. Dropping something is a simple example. If building codes allow, lighting a peanut or walnut on fire is more exciting.

DiscussionTopics

How does the total amount of matter and energy in the universe relate to the Big Bang Theory of the origin of the universe and the role of entropy in the destiny of the universe?

Can we get something for nothing? Explore the attempts of advertising to convince the public that we can indeed get something for nothing. Explore attempts to create perpetual motion machines. Explore the history of the free lunch concept.

Howmuchareyouwillingtopayintheshorttermtoreceivelong-term economicand environmentalbenefits?Explorecostsandpaybacktimesofenergy-efficientappliances,energy-savinglightbulbs,andweatherstripping.

Whatactionscanyoutaketoimproveyourhome’senergyefficiencyandreduceconsumptionofmaterials? Doyoubelievethesereductionswillincreaseordecreaseyourqualityoflife?

Whatisournationalenergypolicy?Howhasitchangedoverthepast20years?Isourcurrentpolicysupportedbythescienceinthischapterregardingthelawsofenergy?Whataretheshort-andlong-termeconomic,environmental,andnational-securityimplications?

Whatwoulditbeliketoleadalow-energylifestyle?Arepeoplealreadysuccessfullyusinglessenergywhilemaintainingahighqualityoflife?Whataresomeofthechallengesinconvincingmorepeopletoembracealow-energylifestyle?

ActivitiesandProjects

Ahumanbodyatrestyieldsheatataboutthesamerateasa100-wattincandescentlightbulb.Asaclassexercise,calculatetheheatproductionofthestudentbodyofyourschool,theU.S.population,andtheglobalpopulation.Wheredoestheheatcomefrom?Wheredoesitgo?

Asaclassexercise,conductasurveyofthestudentsatyourschooltodeterminetheirdegreeofawarenessandunderstandingofthethreebasiclaws of matterandenergy.Discusstheresultsinthecontextoftheneedforlow-entropylifestylesandsustainable-Earthsocieties.

Askaphysics or chemistryinstructortovisityourclassand,byusingsimpleexperiments,demonstratethematterandenergylaws.

Asaclassexercise,make aninventorythetypesofappliancesthatareusedtomaintainaclassroomenvironment—thelighting;spaceheatingandcooling;electricityforprojectors;andotherfacilities,equipment,andservices.Listthematterfromwhichtheyaremadeandtheirapproximatemassandenergyconsumption,ifapplicable.

Inviteamedicaltechniciantospeaktoyourclassonthebeneficialusesofionizingradiation.Discussthe controlsthat are employedtolimittherisksassociatedwiththeuseofradioisotopesfordiagnosticandtreatmentprocedures?

AttitudesandValuesAssessment

Wheredoyoufitintotheflowofenergyfromthesun?

Doyoufeelyouplayaroleinnature’scyclesofmatterandenergy?

Whatisyourbodytemperature?Howdoesyourbodystayatthattemperatureeveninthecoldweather?Howdoyoufeelwhenyouareinair-conditionedorheatedrooms?

Doyouusealotofenergy(e.g.,lights,television,CDplayer,car,orheatedwater)?Wheredoestheenergycomefrom?What could cause you to increaseordecreaseyourusage?

Howdoyoufeelonasunnyday?Acloudyday?Whatisthewinddoingwiththeatmosphericenergyon thosedays?

WhatrightdoyouhavetouseEarth’smaterialresources?Arethereanylimitstoyourrights?Whatarethey?

WhatrightsdoyouhavetoEarth’senergyresources?Arethereanylimitstoyourrights?Whatarethey?

Doyoubelievethatcyclesofmatterandenergyflowingfromthesunhaveanythingtodowithyourlifestyle?Withyourcountry’seconomic or energy policies?

LaboratorySkills

Wells,Edward.LabManualforEnvironmentalScience.2009.Lab#1:IntroductiontoExperimentalDesign.

NewsVideos

AdditionalVideos

Acid Rain The Invisible Threat

Hands-on lab activities plus video.

The Scientific Method Song

A musical explanation of the scientific method

The Scientific Method

An explanation of the history behind the method

WebResources

TheParticleAdventure

AnexplorationofthefundamentalsofmatterfromtheLawrenceBerkeleyLab.

Digital Integration

Correlation to Global Environment Watch

Acid RainGreen Chemistry

Energy Efficiency

Correlation to Explore More

EcologyEnvironmental Science

EnergyNature of Science

Environmental HistoryScience

SuggestedAnswerstoEndofChapterQuestions

Answerswillvarybuttheserepresentphrasesfromthischapter.Thefollowingareexamplesofthematerialthatshouldbecontainedinpossiblestudentanswerstotheendofchapterquestions.Theyrepresentonlyasummaryoverviewandservetohighlightthecoreconceptsthatareaddressedinthetext.Itshouldbeanticipatedthatthestudentswillprovidemorein-depthanddetailedresponsestothequestionsdependingonanindividualinstructor’sstatedexpectations.

Review

Core Case Study

1.Describe the controlled scientific experiment carried out in the Hubbard Brook Experimental Forest.

See page 25.

Section 2-1

2.What is the key concept for this section?Whatisscience?Describethestepsinvolvedinascientificprocess.Whatisdata?Whatisamodel?Distinguishamongascientifichypothesis,a scientifictheory,anda scientificlaw(lawofnature).Whatispeerreviewandwhyisitimportant?Explainwhyscientifictheoriesarenottobetakenlightlyandwhypeopleoftenusethetermtheoryincorrectly.

The key concept for this section is that scientists collect data and develop theories, models, and laws about how nature works.
Scienceisanattempttodiscoverhownatureworksandtousethatknowledgetomakepredictionsaboutwhatislikelytohappeninnature.
Dataistheinformationneededtoanswerscientificquestionsusuallyobtainedbymakingobservationsandmeasurements.
Modelisanapproximaterepresentationorsimulationofasystembeingstudied.
Scientifichypothesisisapossibleandtestableexplanationofwhatisobservedinnatureorintheresultsofexperiments.
Awell-testedandwidelyacceptedscientifichypothesisoragroupofrelatedhypothesesiscalledascientifictheory.
Ascientificlaw,orlawofnatureisawell-testedandwidelyaccepteddescriptionofwhatwefindhappeninginnature.
Animportantpartofthescientificprocessispeerreview,inwhichscientistsopenlypublishdetailsofthemethodsandmodelstheyused,theresultsoftheirexperiments,andthereasoningbehindtheirhypothesesforotherscientistsworkinginthesamefield(theirpeers)toevaluate.Anyevidencegatheredtoverifyahypothesismustbereproducible.Thatis,scientistsshouldrepeatandanalyzetheworktoseeifthedatacanbereproducedandwhethertheproposedhypothesisisreasonableanduseful.
Ascientifictheoryshouldbetakenveryseriously.Ithasbeentestedwidely,supportedbyextensiveevidence,andacceptedbymostscientistsinaparticularfieldorrelatedfieldsofstudy.Nonscientistsoftenusethewordtheoryincorrectlywhentheyactuallymeanscientifichypothesis,atentativeexplanationthatneedsfurtherevaluation.Thestatement,“Oh,that’sjustatheory,”often madeineverydayconversation,impliesthatthetheorywasstatedwithoutproperinvestigationandcarefultesting—theoppositeofthescientificmeaningoftheword.

3.Explainwhyscientifictheoriesandlawsarethemostimportantresultsofscienceand most certain results of science.

Sincethegoalofscienceistocomeupwiththeoriesandlawsbasedonfactstoexplainhowtheworldworks,thesetheoriesandlawsaretheculminationofthescientificprocess,especiallysinceascientificlawcannotbebrokenaslongasthedatausedtoformulateitisaccurate.

4.Distinguishamongtentativescience(frontierscience),reliablescience,andunreliablescience. Whatarethreelimitationsofscienceandenvironmentalscience?

Tentativescienceorfrontierscienceisthepreliminaryresultsthatcapturenewsheadlinesandmaybecontroversialbecausetheyhavenotbeenwidelytestedandacceptedbypeerreviewyet.
Reliablescienceconsistsofdata,hypotheses,theories,andlawsthatarewidelyacceptedbyallormostofthescientistswhoareconsideredexpertsinthefieldunderstudy,inwhatisreferredtoasascientificconsensus.Theresultsofreliablesciencearebasedontheself-correctingprocessoftesting,peerreview,reproducibility,anddebate.Newevidenceandbetterhypothesesmaydiscreditoralteracceptedviews.
Scientifichypothesesandresultsthatarepresentedasreliablewithouthavingundergonetherigorsofpeerreview,orthathavebeendiscardedasaresultofpeerreview,areconsideredtobeunreliablescience.
Environmentalscienceandscienceingeneralhavethreeimportantlimitations:
Scientistscannotproveordisproveanythingabsolutely,becausethereisalwayssomedegreeofuncertaintyinscientificmeasurements,observations,andmodels.
Alimitationofscienceisthatscientistsarehumanandthusarenottotallyfreeofbiasabouttheirownresultsandhypotheses.
Alimitation—especiallyimportanttoenvironmentalscience—isthatmanyenvironmentalphenomenainvolveahugenumberofinteractingvariablesandcomplexinteractions.

Section 2-2

5.What are the two key concepts for this section?Whatismatter?Distinguishbetweenanelementandacompoundandgiveanexampleofeach.Distinguishamongatoms,molecules, and ionsandgiveanexampleofeach.Whatistheatomictheory?Distinguishamongprotons,neutrons,andelectrons.Whatisthenucleusofanatom?Distinguishbetweentheatomicnumberandthemassnumberofanelement.Whatisanisotope?Whatisacidity?WhatispH?

The key concepts for this section are:
Matter consists of elements and compounds, which in turn are made up of atoms, ions, or molecules.
Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).
Matterisanythingthathasmassandtakesupspace.Itcanexistinthreephysicalstates—solid,liquid,andgas,andtwochemicalforms—elementsandcompounds.
Achemicalelementisafundamentalsubstancethathasauniquesetofpropertiesandcannotbebrokendownintosimplersubstancesbychemicalmeans.Compoundsareacombinationsoftwoormoredifferentelementsheldtogetherinfixedproportions.
Themostbasicbuildingblockofmatterisanatom—thesmallestunitofmatterintowhichanelementcanbedividedandstillhaveitscharacteristicchemicalproperties,suchasasinglehydrogenatom.Asecondbuildingblockofsometypesofmatterisanion—anatomorgroupofatomswithoneormorenetpositive(+)ornegative(–)electricalcharges,suchasH+.Amoleculeisacombinationoftwoormoreatomsofthesameelementsheldtogetherbyforcescalledchemicalbonds,suchasO2,oxygen.
Theatomictheoryistheideathatallelementsaremadeupofatoms.
Threedifferenttypesofsubatomicparticles:positivelychargedprotons(p),neutrons(n)withnoelectricalcharge,andnegativelychargedelectrons(e).
Eachatomconsistsofanextremelysmallanddensecentercalleditsnucleus—whichcontainsoneormoreprotonsand,inmostcases,oneormoreneutrons—andoneormoreelectronsmovingrapidlysomewherearoundthenucleus.
Eachatomhasequalnumbersofpositivelychargedprotonsandnegativelychargedelectrons.Becausetheseelectricalchargescanceloneanother,atomsasawholehavenonetelectricalcharge.Eachelementhasauniqueatomicnumber,equaltothenumberofprotonsinthenucleusofitsatom.Themassofanatomisdescribedbyitsmassnumber:thetotalnumberofneutronsandprotonsinitsnucleus.
Formsofanelementhavingthesameatomicnumberbutdifferentmassnumbersarecalledisotopesofthatelement.
Ionsarealsoimportantformeasuringasubstance’sacidityinawatersolution,achemicalcharacteristicthathelpsdeterminehowasubstancedissolvedinwaterwillinteractwithandaffectitsenvironment.
ScientistsusepHasameasureofacidity,basedontheamountofhydrogenions(H+)andhydroxideions(OH–)containedinaparticularvolumeofasolution.

6.Whatisachemicalformula?Distinguishbetweenorganiccompoundsandinorganiccompoundsandgiveanexampleofeach.Distinguishamongcomplexcarbohydrates,proteins,nucleicacids,andlipids.What is a cell?Distinguishamonga gene,a trait,anda chromosome.Whatismatterquality?Distinguishbetweenhigh-qualitymatterandlow-qualitymatterandgiveanexampleofeach.

See pages 32–33. Student answers will vary slightly.

Chemistsuseachemicalformulatoshowthenumberofeachtypeofatomorioninacompound.
Organiccompoundscontainatleasttwocarbonatomscombinedwithatomsofoneormoreotherelement,suchastablesugarandmethane.Allothercompounds,exceptmethane(CH4),arecalledinorganiccompounds,suchwater.
Complexcarbohydrates,suchascelluloseandstarch,consistoftwoormoremonomersofsimplesugars,suchasglucose.
Proteinsareformedbymonomerscalledaminoacids.
Nucleicacids(DNAandRNA)areformedbymonomerscallednucleotides.
Lipids,whichincludefatsandwaxes,arenotallmadeofmonomers,butareafourthtypeofmacromoleculeessentialforlife.
Cellsarethesmallestandmostfundamentalstructuralandfunctionalunitsoflife.
WithinsomeDNAmoleculesarecertainsequencesofnucleotidescalledgenes.EachofthesedistinctpiecesofDNAcontainsinstructions,calledgeneticinformation,formakingspecificproteins.Eachofthesecodedunitsofgeneticinformationconcernsaspecifictrait,orcharacteristic,passedonfromparentstooffspringduringreproduction.Thousandsofgenes,inturn,makeupasinglechromosome,aDNAmolecule combined with proteins.
Matterisanythingthathasmassandtakesupspace.Itcanexistinthreephysicalstates:solid,liquid,andgasandtwochemicalforms:elementsandcompounds.
High-qualitymatterishighlyconcentrated,istypicallyfoundneartheearth’ssurface,andhasgreatpotentialforuseasaresource,coalforexample.Low-qualitymatterisnothighlyconcentrated,isoftenlocateddeepundergroundordispersedintheoceanoratmosphere,andusuallyhaslittlepotentialforuseasaresource,asaltsolutionforexample.

7.Distinguishbetweenaphysicalchangeandachemicalchange(chemicalreaction)andgiveanexampleofeach.What is a nuclear change?Explainthedifferencesamongradioactivedecay,nuclearfission,andnuclearfusion.Whatisthelawofconservationofmatterandwhyisitimportant?

Seepages33–34.Studentanswerswillvaryslightly.

Whenasampleofmatterundergoesaphysicalchange,thereisnochangeinitschemicalcomposition.Apieceofaluminumfoilcutintosmallpiecesisstillaluminumfoil.
Whenachemicalchange,orchemicalreaction,takesplacethereisachangeinchemicalcompositionofthesubstancesinvolved.Chemistsuseachemicalequationtoshowwhathappensinachemicalreaction.Forexample,whencoalburnscompletely,thesolidcarbon(C)inthecoalcombineswithoxygengas(O2)fromtheatmospheretoformthegaseouscompoundcarbondioxide(CO2).
Nuclear change is a change in the nucleus of an atom.
Radioactivedecayoccurswhennucleiofunstableisotopesspontaneouslyemitfast-movingchunksofmatter(alphaparticlesorbetaparticles),high-energyradiation(gammarays),orbothatafixedrate.
Nuclearfissionoccurswhenthenucleiofcertainisotopeswithlargemassnumbers(suchasuranium-235)aresplitapartintolighternucleiwhenstruckbyaneutronandreleaseenergyplustwoorthreemoreneutrons.
Nuclearfusionoccurswhentwoisotopesoflightelements,suchashydrogen,areforcedtogetheratextremelyhightemperaturesuntiltheyfusetoformaheaviernucleusandreleaseatremendousamountofenergy.
Thelawofconservationofmatterstateswhenevermatterundergoesaphysicalorchemicalchange,noatomsarecreatedordestroyed.Thislawhelpsusunderstandthatweneedtoletourwastecyclebacktoitsoriginalnutrients/productsinorderforourresourcestobesustainable.

Section 2-3

8.What are the two key concepts for this section?Whatisenergy?Distinguishbetweenkineticenergyandpotentialenergyandgiveanexampleofeach.Whatisheat?Defineandgivetwoexamplesofelectromagneticradiation.What are fossil fuels and what three fossil fuels do we use to provide most of the energy that we use to supplement energy from the sun?Whatisenergyquality?Distinguishbetweenhigh-qualityenergyandlow-qualityenergyandgiveanexampleofeach.

Seepages35–36.Studentanswerswillvaryslightly.

The key concepts for this section are:
Whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).
Whenever energy is converted from one form to another in a physical or chemical change, we end up with lower quality or less usable energy than we started with (second law of thermodynamics).
Energy is the capacity to do work or transfer heat.
Therearetwomajortypesofenergy:movingenergy(calledkineticenergy)andstoredenergy(calledpotentialenergy).Examplesofkineticenergyincludewind(amovingmassofair),flowingwater,andelectricity(flowingelectrons).Anexampleofpotentialenergyisgasoline.
Heatisaformofkineticenergy,thetotalkineticenergyofallmovingatoms,ions,ormoleculeswithinagivensubstance.Whentwoobjectsatdifferenttemperaturescontactoneanother,heatflowsfromthewarmerobjecttothecoolerobject.

Electromagneticradiationisenergythattravelsintheformofawaveasaresultofchangesinelectricalandmagneticfields.FormsofelectromagneticradiationareshortwavelengthssuchasgammaraysandXrays.
Fossil fuels were formed over millions of years as layers of the decaying remains of ancient plants and animals were exposed to intense heat and pressure within the earth’s crust.
Oil, coal, and natural gas supply most of the commercial energy that we use to supplement energy from the sun.
Energyqualityisameasureofanenergysource’scapacitytodousefulwork.
High-qualityenergyisconcentratedandhasahighcapacitytodousefulwork.Examplesareveryhigh-temperatureheat,nuclearfission,concentratedsunlight,high-velocitywind,andenergyreleasedbyburningnaturalgas,gasoline,orcoal.
Low-qualityenergyisdispersedandhaslittlecapacitytodousefulwork.Anexampleisheatdispersedinthemovingmoleculesofalargeamountofmatter(suchastheatmosphereoranocean)sothatitstemperatureislow.

9.Whatisthefirstlawofthermodynamics(lawofconservationofenergy)andwhyisitimportant?Whatisthesecondlawofthermodynamicsandwhyisitimportant?Explainwhythesecondlawmeansthatwecanneverrecycleorreusehigh-qualityenergy.

Seepage36.Studentanswerswillvaryslightly.

Thefirstlawofthermodynamics,alsoknownasthelawofconservationofenergy,statesthatwheneverenergyisconvertedfromoneformtoanotherinaphysicalorchemicalchange,noenergyiscreatedordestroyed.Thisscientificlawtellsusthatnomatterhowhardwetryorhowcleverweare,wecannotgetmoreenergyoutofaphysicalorchemicalchangethanweputinbecauseenergyinputalwaysequalsenergyoutput.
Thesecondlawofthermodynamicsstatesthatwhenenergyischangedfromoneformtoanother,italwaysgoesfromamoreusefultoalessusefulform.
Wecanneverrecycleorreusehigh-qualityenergybecausewheneverenergyisconvertedfromoneformtoanother,wealwaysendupwithalowerqualityorless“usable”energythanwestartedwith.

10.Whatarethischapter’sthreebigideas?RelatethethreeprinciplesofsustainabilitytotheHubbardBrookExperimentalForestcontrolledexperiment.

Seepage37 andtheHubbardBrookExperiment.Studentanswersshouldslightlyvary.

Thethreebigideasofthischapter:
Thereisnoaway.Accordingtothelawofconservationofmatter,noatomsarecreatedordestroyedwhenevermatterundergoesaphysicalorchemicalchange.Thus,wecannotdoawaywithchemicals;wecanonlychangethemfromonephysicalstateorchemicalformtoanother.
Youcannotgetsomethingfornothing.Accordingtothefirstlawofthermodynamics,orlawofconservationofenergy,noenergyiscreatedordestroyedwheneverenergyundergoesaphysicalorchemicalchange.Thismeansthatinsuchchangeswecannotgetmoreenergyoutthanweputin.
Youcannotbreakeven.Accordingtothesecondlawofthermodynamics,wheneverenergyisconvertedfromoneformtoanotherinaphysicalorchemicalchange,wealwaysendupwithlowerqualityorlessusableenergythanwestartedwith.

CriticalThinking

WhatecologicallessoncanwelearnfromthecontrolledexperimentontheclearingofforestsdescribedintheCoreCaseStudythatopenedthischapter?

Vegetationcontrolswaterandnutrientlossfromecosystems.Lossofvegetationdiminishesthesystems’abilitytoretainnutrientsandwater.

Youobservethatallofthefishinapondhavedisappeared.DescribehowyoumightusethescientificprocessdescribedintheCoreCaseStudyandFigure 2-2 on p. 27todeterminethecauseofthisfishkill.

AnswerswillvarybutthestepsinFigure2.2forthescientificprocessshouldbefollowed.Observation:thefishkill;Question:Whatcausedthefishtodie?Hypothesis:Maybethedissolvedoxygenwastoolow;Testthehypothesiswithanexperiment:Measurethedissolvedoxygenlevel;Result:Dissolvedoxygenlevelistoolow;Conclusion:Hypothesisisverified.

3.Respond to the following statements:

a.Scientists have not absolutely proven that anyone has ever died from smoking cigarettes.

b.The natural greenhouse theory—that certain gases such as water vapor and carbon dioxide warm the lower atmosphere—is not a reliable idea because it is just a scientific theory.

(a) The medical and scientific evidence that links smoking to premature death caused by a number of pathological conditions is overwhelming. As we are exposed to many chemical hazards in our environment it is often difficult to specifically link the cause and effect. The chances of an individual dying from smoking one cigarette is statistically negligible and highly unlikely, but many years of heavy smoking has a much higher probability that a disease leading to death could result.

(b) Sometimes people with a limited knowledge of the scientific method often confuse a theory with a hypothesis. A theory has been widely tested and is endorsed by a wide group of scientists working in that particular field of study. Many scientists concur with the scientific evidence, obtained through conducting controlled experiments, that water and carbon dioxide are greenhouse gases.

4.A tree grows and increases its mass. Explain why this phenomenon is not a violation of the law of conservation of matter.

The growth of a tree is an example of a chemical change or chemical reaction. Small inorganic elements and compounds are combined to form more complex molecules that make up the material found in the tree. The components that were present in the soil and air have been rearranged to form other types of chemical components. The amount of material that was present before this rearrangement or chemical change took place is the same as the amount afterwards. A student may discuss photosynthesis to support and explain their answer.