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Chapter 2
Science, Systems, Matter, and Energy
Chapter Overview Questions
What is science, and what do scientists do? What are major components and behaviors
of complex systems? What are the basic forms of matter, and what
makes matter useful as a resource? What types of changes can matter undergo
and what scientific law governs matter?
Chapter Overview Questions (cont’d)
What are the major forms of energy, and what makes energy useful as a resource?
What are two scientific laws governing changes of energy from one form to another?
How are the scientific laws governing changes of matter and energy from one form to another related to resource use, environmental degradation and sustainability?
Updates Online
The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles.
InfoTrac: Underwater Microscope Finds Biological Treasures in Subtropical Ocean. Ascribe Higher Education News Service, June 26, 2006.
InfoTrac: In Bacterial Diversity, Amazon Is a 'Desert'; Desert Is an 'Amazon'. Ascribe Higher Education News Service, Jan 9, 2006.
InfoTrac: Making MGP wastes beneficial. Bob Paulson. Pollution Engineering, June 2006 v38 i6 p20(5).
NASA: Nitrogen Cycle Environmental Literacy Council: Phosphorous Cycle National Sustainable Agriculture Information Service: Nutrient Cycles
Video: The Throw Away Society
This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.
Core Case Study: Environmental Lesson from Easter
Island Thriving society
15,000 people by 1400. Used resources faster
than could be renewed By 1600 only a few
trees remained. Civilization collapsed
By 1722 only several hundred people left.
Figure 2-1
THE NATURE OF SCIENCE
What do scientists do? Collect data. Form hypotheses. Develop theories,
models and laws about how nature works.
Figure 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 Most Important Results of Science
Scientific Theory Widely tested and
accepted hypothesis.
Scientific Law What we find
happening over and over again in nature.
Figure 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 Hypotheses
Scientists test hypotheses using controlled experiments and constructing mathematical models. Variables or factors influence natural processes Single-variable experiments involve a control and
an experimental group. Most environmental phenomena are
multivariable and are hard to control in an experiment.• Models are used to analyze interactions of variables.
Scientific Reasoning and Creativity
Inductive reasoning Involves using specific observations and
measurements to arrive at a general conclusion or hypothesis.
Bottom-up reasoning going from specific to general.
Deductive reasoning Uses logic to arrive at a specific conclusion. Top-down approach that goes from general to
specific.
Frontier Science, Sound Science, and Junk Science
Frontier science has not been widely tested (starting point of peer-review).
Sound science consists of data, theories and laws that are widely accepted by experts.
Junk science is presented as sound science without going through the rigors of peer-review.
Limitations of Environmental Science
Inadequate data and scientific understanding can limit and make some results controversial. Scientific testing is based on disproving rather
than proving a hypothesis.• Based on statistical probabilities.
MODELS AND BEHAVIOR OF SYSTEMS
Usefulness of models Complex systems are predicted by developing a
model of its inputs, throughputs (flows), and outputs of matter, energy and information.
Models are simplifications of “real-life”. Models can be used to predict if-then scenarios.
Feedback Loops: How Systems Respond to Change
Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing. Positive feedback loop causes a system to
change further in the same direction (e.g. erosion)
Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. seeking shade from sun to reduce stress).
Feedback Loops:
Negative feedback can take so long that a system reaches a threshold and changes. Prolonged delays may prevent a negative
feedback loop from occurring. Processes and feedbacks in a system can
(synergistically) interact to amplify the results. E.g. smoking exacerbates the effect of asbestos
exposure on lung cancer.
TYPES AND STRUCTURE OF MATTER
Elements and Compounds Matter exists in chemical forms as elements and
compounds.• Elements (represented on the periodic table) are the
distinctive building blocks of matter.• Compounds: two or more different elements held
together in fixed proportions by chemical bonds.
Atoms
Figure 2-4
Ions
An ion is an atom or group of atoms with one or more net positive or negative electrical charges.
The number of positive or negative charges on an ion is shown as a superscript after the symbol for an atom or group of atoms Hydrogen ions (H+), Hydroxide ions (OH-) Sodium ions (Na+), Chloride ions (Cl-)
The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution.
Figure 2-5
Compounds and Chemical Formulas
Chemical formulas are shorthand ways to show the atoms and ions in a chemical compound. Combining Hydrogen ions (H+) and Hydroxide
ions (OH-) makes the compound H2O (dihydrogen oxide, a.k.a. water).
Combining Sodium ions (Na+) and Chloride ions (Cl-) makes the compound NaCl (sodium chloride a.k.a. salt).
Organic Compounds: Carbon Rules
Organic compounds contain carbon atoms combined with one another and with various other atoms such as H+, N+, or Cl-.
Contain at least two carbon atoms combined with each other and with atoms. Methane (CH4) is the only exception. All other compounds are inorganic.
Organic Compounds: Carbon Rules
Hydrocarbons: compounds of carbon and hydrogen atoms (e.g. methane (CH4)).
Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms (e.g. DDT (C14H9Cl5)).
Simple carbohydrates: certain types of compounds of carbon, hydrogen, and oxygen (e.g. glucose (C6H12O6)).
Cells: The Fundamental Units of Life
Cells are the basic structural and functional units of all forms of life. Prokaryotic cells
(bacteria) lack a distinct nucleus.
Eukaryotic cells (plants and animals) have a distinct nucleus.
Figure 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)
Macromolecules, DNA, Genes and Chromosomes Large, complex organic
molecules (macromolecules) make up the basic molecular units found in living organisms. Complex carbohydrates Proteins Nucleic acids Lipids
Figure 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 Matter
The atoms, ions, and molecules that make up matter are found in three physical states: solid, liquid, gaseous.
A fourth state, plasma, is a high energy mixture of positively charged ions and negatively charged electrons. The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in
TV screens, gas discharge lasers, florescent light).
Matter Quality
Matter can be classified as having high or low quality depending on how useful it is to us as a resource. High quality matter is
concentrated and easily extracted.
low quality matter is more widely dispersed and more difficult to extract.
Figure 2-8
Matter Quality It is the measure of how useful a form of
matter is as a resource Based on AVAILABILITY and CONCENTRATION
High Quality Easy to extract Found near earth’s surface Great potential for use as a material resource
Low Quality Dilute Usually deep underground or dispersed in the ocean or
atmosphere Has little potential for use as material resource
Aluminum Can
A more concentrated, Higher Quality matter than aluminum ore that contains the same amount of aluminum
Less energy, water and energy to recycle an aluminum can compared to making a brand new aluminum can
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 MATTER Matter can change from one physical form to
another or change its chemical composition. When a physical or chemical change occurs, no
atoms are created or destroyed.• Law of conservation of matter.
Physical change maintains original chemical composition.• Different spatial arrangement
Chemical change involves a chemical reaction which changes the arrangement of the elements or compounds involved.• Chemical equations are used to represent the
reaction.• Rearrangement of atoms
Chemical Change
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 Pollutants Factors that determine the severity of a pollutant’s effects: Chemical nature Concentration
ppm-parts per million…• One part pollutant to a million parts of liquid, gas, or
solid mixture it is part of Persistence
How long it stays in water, air, soil, body Pollutants are classified based on their persistence:
Degradable pollutants Biodegradable pollutants Slowly degradable pollutants Nondegradable pollutants
Types of Pollutants Degradable pollutants
• Non - persistent• Can be broken down completely or reduced to acceptable
levels by natural physical, chemical or biological processes
Biodegradable pollutants• Complex chemicals that specialized living organisms
(certain bacteria) can break down into simpler chemicals (ie human sewage)
Slowly degradable pollutants• Persistent pollutant that last for a decade or longer (ie
DDT pesticide) Nondegradable pollutants
• Chemical that cannot be broken down by natural processes (lead, mercury, arsenic)
ENERGY
Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion
• heat, electromagnetic radiation Potential energy – stored for possible use
• batteries, glucose molecules
3 Ways Heat Can Be Transferred Convection
When warmer particles rise and the fall as then cool down
Conduction Particles move and transfer
energy to particles around them, until they are all heated to the point where they are moving so fast they are too hot to touch
Radiation When heat from the
hot/heated material radiates to the surrounding air
Electromagnetic Spectrum
Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content.
Figure 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
EM Spectrum Ionizing radiation
Cosmic rays, gamma rays, X-rays, UV rays Contain enough energy to knock electrons off of atoms and
create positively charged particles Result is highly reactive electrons and ions…DANGEROUS!
• Genetic damage Cause disruptions in DNA that is passed down to offspring
• Somatic damage Causes damage to tissue structure Burns, miscarriages, cataracts, cancers
Nonionizing radiation Not enough energy to knock off electrons and
create ions
Electromagnetic Spectrum
Organisms vary in their ability to sense different parts of the spectrum.
Figure 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
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 CANNOT BREAK
The first law of thermodynamics: we cannot create or destroy energy. We can change energy from one form to another.
The second law of thermodynamics: energy quality always decreases. When energy changes from one form to another,
it is always degraded to a more dispersed form. Energy efficiency is a measure of how much
useful work is accomplished before it changes to its next form.
Laws of Thermodynamics
1) Cannot create or destroy energy, only transfer or change form
2) When energy changes form, some energy is always degraded to lower quality, more dispersed, less useful forms of energy (more useful to less useful)
Fig. 2-14, p. 45
Chemicalenergy(food)
Solarenergy
WasteHeat
WasteHeat
WasteHeat
WasteHeat
Mechanicalenergy
(moving,thinking,
living)
Chemical energy
(photosynthesis)
• Atoms with the same atomic number but with different atomic masses are called isotopes
• Changing the # of neutrons in an atom will affect the…– MASS NUMBER= protons +
neutrons• Isotopes of an element have the
same # of p+ and e-…so they behave the same CHEMICALLY
• The average of all the mass #s of the isotopes of an element give us that decimal on the periodic table (Average Atomic Mass)
Radioactive Isotopes• As the difference b/t p+ and n. in the
nucleus increases, the nucleus becomes more unstable– When p=n , nucleus is stable…– When n>p or n<p, nucleus is unstable– Nucleus will give off tiny amounts of energy to
become stable (protons or neutrons)• Radiation=energy• Radioactive=when something gives off
energy
Isotopes of the Element Potassium with a Known Natural Abundance
• Mass # Natural Abundance Half-life • 39 93.2581% Stable • 40 0.0117% 1.265×10+9 years • 41 6.7302% Stable
Isotopes continued
• Radiation can be dangerous in large amounts but in small amounts it can be useful in science– Geology-determine age of fossils
and rocks– Medicine-treat cancer and detect
cell processes (tracers)• PET scans, CT scans, MRI
– Commercial-kill bacteria that spoils certain foods
Nuclear Changes: Radioactive Decay
Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of matter (alpha or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. Radiation is commonly used in energy production
and medical applications. The rate of decay is expressed as a half-life (the
time needed for one-half of the nuclei to decay to form a different isotope).
Half-life (HL) Time needed for one-half of the nuclei to decay
to form a different isotope Emits radiation to form different isotope Decay continues until stable nuclei is
produced…forms various radioactive isotopes Each radioactive isotope has a characteristic
HL HL cannot be changed by temperature,
pressure, chemical rxns, or other known factors
Half Life continued Use HL to estimate how long a sample radioactive isotope must
be stored in a safe container before it decays to what is considered a safe level
General rule: takes about 10 half-lives to reach this “safe” level Radioactive Iodine-131
Concentrated in thyroid gland HL= 8 days How long to reach a safe level?
• 10 x 8 days = 80 days Radioactive Plutonium-239
Produced in nuclear reactors and used as explosive in nuclear weapons
HL= 24,000 years How long to reach a safe level?
• 10 x 24,000= 240,000 years
Nuclear Changes: Fission
Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons.
Figure 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
Stepped Art
Nuclear Changes: Fusion
Nuclear fusion: two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus.
Figure 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
+
SUSTAINABILITY AND MATTER AND ENERGY LAWS
Unsustainable High-Throughput Economies: Working in Straight Lines Converts resources to goods in a manner that
promotes waste and pollution.
Figure 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 Economies: Learning from Nature
Matter-Recycling-and-Reuse Economies: Working in Circles Mimics nature by recycling and reusing, thus
reducing pollutants and waste. It is not sustainable for growing populations.
Fig. 2-14, p. 45
Chemicalenergy(food)
Solarenergy
WasteHeat
WasteHeat
WasteHeat
WasteHeat
Mechanicalenergy
(moving,thinking,
living)
Chemical energy
(photosynthesis)
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)