Chapter 3
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?
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
Video: Easter Island
https://www.youtube.com/watch?v=v40kCIpgEWw
THE NATURE OF SCIENCE
• What do scientists do?
– Collect data.
– Form hypotheses.
– Develop theories,
models and laws about
how nature works.
Figure 2-2
Ask a question
Do experiments
and collect data
Interpret data
Formulate hypothesis
to explain data
Well-tested and
accepted patterns
in data become
scientific laws
Do more experiments
to test hypothesis
Revise hypothesis
if necessary
Well-tested and
accepted
hypotheses
become
scientific theories
Fig. 2-2, p. 29
Ask a question
Do experiments
and collect data
Interpret data
Formulate hypothesis
to explain data
Well-tested and
accepted patterns
In data become
scientific laws
Do more experiments
to test hypothesis
Revise hypothesis
if necessary
Well-tested and
accepted
hypotheses
become
scientific theories
Stepped Art
Fig. 2-3, p. 30
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
Research results
Scientific paper
Peer review by
experts in field
Paper
rejected
Paper accepted
Paper published in
scientific journal
Research evaluated
by scientific
community
Fig. 2-3, p. 30
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 peerreview.
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
(a) Prokaryotic Cell
DNA
(information storage, no nucleus)
Protein construction
and energy conversion
occur without specialized
internal structures
Cell membrane
(transport of
raw materials and
finished products)
Fig. 2-6a, p. 37
(b) Eukaryotic Cell
Nucleus
(information
storage)
Energy
conversion
Protein
construction
Packaging
Cell membrane
(transport of raw
materials and
finished products)
Fig. 2-6b, p. 37
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
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.
The genes in each cell are coded by
sequences of nucleotides in their DNA
molecules.
Fig. 2-7, p. 38
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.
The genes in each cell are coded
by sequences of nucleotides in
their DNA molecules.
Stepped Art
Fig. 2-7, p. 38
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
High Quality
Low Quality
Solid
Salt
Solution of salt in water
Coal
Coal-fired power plant emissions
Gasoline
Aluminum can
Gas
Automobile emissions
Aluminum ore
Fig. 2-8, p. 39
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.
– Chemical change involves a chemical reaction
which changes the arrangement of the elements
or compounds involved.
• Chemical equations are used to represent the
reaction.
Chemical Change
• Energy is given off during the reaction as a product.
Reactant(s)
Product(s)
carbon
+
oxygen
carbon dioxide
+
energy
C
+
O2
CO2
+
energy
+
black solid
+
colorless gas
energy
colorless gas
p. 39
Types of Pollutants
• Factors that determine the severity of a
pollutant’s effects: chemical nature,
concentration, and persistence.
• Pollutants are classified based on their
persistence:
– Degradable pollutants
– Biodegradable pollutants
– Slowly degradable pollutants
– Nondegradable pollutants
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).
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
Uranium-235
Uranium-235
Uranium-235
Energy
Fission
Fragment
Uranium-235
n
n
Neutron
n
Energy
Uranium-235
Fission
Fragment
n
Energy
n
Uranium-235
n
Uranium-235
Energy
Uranium-235
Uranium-235
Uranium-235
Fig. 2-9, p. 41
Uranium-235
Uranium-235
Uranium-235
Energy
Fission
fragment
Uranium-235
n
n
Neutron
n
n
Energy
n
Uranium-235
Uranium-235
Energy
n
Fission
fragment
Uranium-235
Energy
Uranium-235
Uranium-235
Uranium-235
Stepped Art
Fig. 2-6, p. 28
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
Reaction
Conditions
Fuel
Proton
Products
Neutron
Energy
Hydrogen-2
(deuterium nucleus)
+
+
+
100
million °C
Helium-4 nucleus
+
Hydrogen-3
(tritium nucleus)
Neutron
Fig. 2-10, p. 42
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
Electromagnetic Spectrum
• Many different forms of electromagnetic
radiation exist, each having a different
wavelength and energy content.
Figure 2-11
Sun
Ionizing radiation
Cosmic Gamma X rays
rays
Rays
High energy, short
Wavelength
Far
ultraviolet
waves
Nonionizing radiation
Near
Near
ultra- Visible infrared
violet Waves
waves
waves
Wavelength in meters
(not to scale)
Far
infrared
waves
Microwaves
TV
waves
Radio
Waves
Low energy, long
Wavelength
Fig. 2-11, p. 43
Electromagnetic Spectrum
• Organisms vary
in their ability to
sense different
parts of the
spectrum.
Figure 2-12
Ultraviolet
Energy emitted from sun (kcal/cm2/min)
Visible
Infrared
Wavelength (micrometers)
Fig. 2-12, p. 43
Source of Energy
Electricity
Very high temperature heat
(greater than 2,500°C)
Nuclear fission (uranium)
Nuclear fusion (deuterium)
Concentrated sunlight
High-velocity wind
Relative
Energy Tasks
Energy Quality
(usefulness)
Very high-temperature heat
(greater than 2,500°C) for
industrial processes and
producing electricity to run
electrical devices (lights,
motors)
High-temperature heat
(1,000–2,500°C)
Hydrogen gas
Natural gas
Gasoline
Coal
Food
Mechanical motion to move
vehicles and other things)
High-temperature heat
(1,000–2,500°C) for
industrial processes and
producing electricity
Normal sunlight
Moderate-velocity wind
High-velocity water flow
Concentrated geothermal energy
Moderate-temperature heat
(100–1,000°C)
Wood and crop wastes
Moderate-temperature heat
(100–1,000°C) for
industrial processes, cooking,
producing
steam, electricity, and
hot water
Dispersed geothermal energy
Low-temperature heat
(100°C or lower)
Low-temperature heat
(100°C or less) for
space heating
Fig. 2-13, p. 44
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.
Chemical
energy
(photosynthesis)
Solar
energy
Waste
Heat
Mechanical
energy
(moving,
thinking,
living)
Chemical
energy
(food)
Waste
Heat
Waste
Heat
Waste
Heat
Fig. 2-14, p. 45
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
System
Throughputs
Inputs
(from environment)
High-quality energy
Matter
Outputs
(into environment)
Unsustainable
high-waste
economy
Low-quality energy (heat)
Waste and pollution
Fig. 2-15, p. 46
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.
Inputs
(from environment)
Energy
Matter
System
Throughputs
Outputs
(into environment)
Energy
conservation
Waste
and
pollution
Low-quality
Energy
(heat)
Sustainable
low-waste
economy
Pollution
control
Matter
Feedback
Waste
and
pollution
Recycle
and
reuse
Energy Feedback
Fig. 2-16, p. 47