Chapter 2:Science, Matter, Energy and Systems

APES, Fall 2013

Controlled experiment (case study)F. Herbert Bormann, Gene Likens, et al.:

Hubbard Brook Experimental Forest in NH (U.S.)

Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)

The Effects of Deforestation on the Loss of Water and Soil Nutrients

What is scienceConcept 2-1 Scientists collect data and

develop theories, models, and laws about how nature works.

Science Is a Search for Order in Nature Identify a problemFind out what is known about the problemAsk a question to be investigatedGather dataHypothesizeMake testable predictions Keep testing and making observationsAccept or reject the hypothesis

Scientific Theories and Laws Are the Most Important Results of ScienceScientific theory – Explanation of what happens

Widely testedSupported by extensive evidenceAccepted by most scientists in a particular area

Scientific law, law of nature – Statement of what happensWidely testedSupported by extensive evidenceAccepted by most scientists in a particular area

Paradigm shift

The Results of Science Can Be Tentative, Reliable, or UnreliableTentative science, frontier science

Reliable science

Unreliable science

(but all science is tentative, right?)Non-science??

Science Focus: Statistics and ProbabilityStatistics

Collect, organize, and interpret numerical data

ProbabilityThe chance that something will happen or be

valid

2-2 What is matter?Concept 2-2 Matter consists of elements and

compounds, which are in turn made up of atoms, ions, or molecules.

Matter Consists of Elements and CompoundsMatter

Has mass and takes up spaceElements

Unique propertiesCannot be broken down chemically into other

substancesCompounds

Two or more different elements bonded together in fixed proportions

Elements important to Env Sci

Ions Important to Env Sci

Atoms, Ions, and Molecules Are the Building Blocks of Matter Atomic theorySubatomic particles

Protons (p) with positive charge and neutrons (0) with no charge in nucleus

Negatively charged electrons (e) orbit the nucleusMass number

Protons plus neutronsIsotopes

Variants of an element with different massesAlso different number of neutrons

Atoms, Ions, and Molecules Are the Building Blocks of Matter Ions

Gained or lost electronsForm ionic compounds

pHMeasure of acidity or basicityH+ and OH-1-7 = acidic, 7-14 = basic (7 = neutral)

Atoms, Ions, and Molecules Are the Building Blocks of Matter Molecule

Two or more atoms of the same or different elements held together by chemical bonds

Chemical formulaSymbols and numbers used to represent the

elements in a compound and their relative proportions

Model of a Carbon-12 Atom

Loss of NO3- from Deforested Watershed

Organic Compounds Are the Chemicals of LifeInorganic compounds – no C+HOrganic compounds – CH

Hydrocarbons and chlorinated hydrocarbonsSimple carbohydrates - CHOMacromolecules: complex organic molecules

Complex carbohydrates - CHO Proteins - CHON, amino acid chain Nucleic acids - CHONPS, DNA and RNA, GCTA,

GCAU Lipids - large, water insoluble, CHO

Matter Comes to Life through Genes, Chromosomes, and CellsCells: fundamental units of lifeGenes: sequences of nucleotides within the

DNAChromosomes: composed of many genes

A human body contains trillionsof cells, each with an identical setof genes.

Each human cell (except for redblood cells) contains a nucleus.

Each cell nucleus has an identical setof chromosomes, which are found inpairs.

A specific pair of chromosomescontains one chromosome from eachparent.

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.

Some Forms of Matter Are More Useful than OthersHigh-quality matter: easily used by people

Low-quality matter: Not easily used

High Q Low Q Figure 2.6High-quality matter is fairly easy to extract and is highly concentrated;

Low-quality matter is not highly concentrated and is more difficult to extract than high-quality matter.

WATER can even be low quality, IF…

2-3 How Can Matter Change?Concept 2-3 When matter undergoes a

physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

Matter Undergoes Physical, Chemical, and Nuclear ChangesPhysical changeChemical change, chemical reactionNuclear change

Natural radioactive decay Radioisotopes: unstable

Nuclear fissionNuclear fusion

Decay Alpha particle(helium-4 nucleus)

Radioactive isotope

Beta particle (electron)

Gamma rays

Fission

FusionProton Neutron

Hydrogen-2(deuterium nucleus)

Hydrogen-3(tritium nucleus)

100million °C

Helium-4 nucleus

Energy

Neutron

We Cannot Create or Destroy MatterLaw of conservation of matterMatter consumption

Matter is converted from one form to another

2-4 What is Energy and How Can It Be Changed?Concept 2-4A When energy is converted

from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).

Concept 2-4B Whenever energy is changed from one form to another, we end up with lower- quality or less usable energy than we started with (second law of thermodynamics).

Energy Comes in Many FormsKinetic energy

Heat Transferred by radiation, conduction, or convection

Electromagnetic radiationPotential energy

Stored energy In the nucleus (nuclear), in bonds (chemical),

gravitationalCan be changed into kinetic energy

Some Types of Energy Are More Useful Than OthersHigh-quality energyLow-quality energy

The 2nd Law of Thermodynamics in Living Systems

Energy Changes Are Governed by Two Scientific LawsFirst Law of Thermodynamics

Energy input always equals energy outputSecond Law of Thermodynamics

Energy always goes from a more useful to a less useful form when it changes from one form to another

Also, (The zeroth law – seriouslyA=B, B=C, then A=C for temperatures.)

Energy efficiencyIn cars – 6% of gasoline combustion = kinetic

energy. 94% = heat.

Incandescent bulbs – 5% light, 95% heat

Estimated: 84% of E in US is wasted, 41% as heat, 43% wasted

2-5 What Are Systems and How Do They Respond to Change?Concept 2-5A Systems have inputs, flows,

and outputs of matter and energy, and their behavior can be affected by feedback.

Concept 2-5B Life, human systems, and the earth’s life support systems must conform to the law of conservation of matter and the two laws of thermodynamics.

Systems Have Inputs, Flows, and OutputsSystem

Inputs from the environmentFlows, throughputsOutputs

Systems Respond to Change through Feedback LoopsPositive feedback loopNegative, or corrective, feedback loop

Positive feedback =/= Good!

Negative feedback maintains conditions

Time Delays Can Allow a System to Reach a Tipping Point

Time delays varyBetween the input of a feedback stimulus and

the response to itTipping point, threshold level

Causes a shift in the behavior of a system

System Effects Can Be Amplified through SynergySynergistic interaction, synergy

HelpfulHarmful

E.g., Smoking and inhaling asbestos particles

Human Activities Can Have Unintended Harmful ResultsDeforested areas turning to desertCoral reefs dyingGlaciers meltingSea levels rising

FRQ’s Sci notation is useful!!