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LIVING IN THE ENVIRONMENT 17THMILLER/SPOOLMAN
CHAPTER 2
Science, Matter, Energy, and Systems
Terminology checklist
Lesson objectives:1. Define science2. explain the scientific method and its application to the study of environmental problems.
Science is a human effort to discover how the
physical world works by making observations and
measurements,and carrying out experiments.
Scientists collect data and develop theories,
models, and laws about how nature works.
Core Case Study: A Story About
a Forest• Hubbard Brook
Experimental Forest in New
Hampshire
• Compared the loss of water
and nutrients from an uncut
forest (control site) with one
that had been stripped
(experimental site)
• Stripped site:
• 30-40% more runoff
• More dissolved nutrients
• More soil erosion
Lesson objectives:1. Define science2. explain the scientific method and its application to the study of environmental problems.
Science is a Search for Order in Nature
• Identify a problem
• Find out what is known about the problem
• Ask a question to be investigated
• Gather data through experiments
• Propose a scientific hypothesis OR
• Make testable predictions
• Keep testing and making observations
• Accept or reject the hypothesis
• Scientific theory: well-tested and widely accepted hypothesis
Testing a Hypothesis
Fig. 2-3, p. 33
The Scientific Process
Fig. 2-2, p. 33
KEY WORDS
• hypothesis are tentative and testable statements
that must be capable of being supported or not
supported by observational evidence.
• Data – information required to answer the
scientists questions
• Model – an approximate representation or
simulation of a system being studied.
• Scientific Theory – a well-tested and widely
accepted scientific hypothesis or a group of related
hypothesis
Scientific Theories and Laws Are the
Most Important Results of Science
• Scientific theory
• Widely tested
• Supported by extensive
evidence
• Accepted by most
scientists in a particular
area
• Scientific law, law of nature
• Scientific Law – a well tested and widely accepted description of what we find happening over and over again, the exact same way in nature.
Characteristics of Science…and
Scientists
• Curiosity
• Skepticism
• Reproducibility
• Peer review
• Openness to new
ideas
• Critical thinking
• Creativity
Three critical components to any “good science”
1) Skepticism: Do not believe what you see until verified
2) Reproducible: data and results should be able to be done over and over
3) Peer Review: other scientists must review work (vs. “Junk science”)
KEY WORDS
Scientific Law – a well tested and widely accepted description of
what we find happening over and over again, the exact same way
in nature.
Peer Review – scientists sharing information with other scientists
working in the same field.
Inductive Reasoning – using specific observations and
measurements to arrive at a general conclusion or hypothesis.
Deductive Reasoning – using logic to arrive at a specific
conclusion based on generalization or premise.
Science Focus: Easter Island: Revisions
to a Popular Environmental Story
• Some revisions to a
popular environmental
story
• Polynesians arrived
about 800 years ago
• Population may have
reached 3000
• Used trees in an
unsustainable manner,
but rats may have
multiplied and eaten
the seeds of the trees
KEY WORDS• Paradigm Shift – when the majority of scientists in a field
accept new ideas and discoveries and build a new framework
for laws and theories, overthrowing older laws and theories.
• Tentative Science/Frontier Science – hypotheses that have
not been widely tested or studied and have not been accepted
by peer review; tend to capture news and headlines.
• Reliable Science – consists of data, hypotheses, theories,
and laws that are widely accepted
• Unreliable Science - Scientific hypotheses and results that
are presented as reliable without having undergone the rigors
of widespread peer review or that have been discarded as a
result of peer review
The Results of Science Can Be Tentative, Reliable, or Unreliable
• Tentative science, frontier science
• Reliable science
• Unreliable science
Scientists can do 2 major things:
1) Attempts to disprove things
2) Can establish that a particular model, theory, or law has a high degree of certainty of being true. NOT ABSOLUTELY TRUE
Scientists should not say“Cigarettes Cause Cancer” but can say “There is overwhelming evidence (SUPPORTS/ DOES NOT SUPPORT!) from thousands of studies that indicate a relationship between cigarette usage and lung cancer”
Science Has Some Limitations
1. Particular hypotheses, theories, or laws have a high
probability of being true while not being absolute
2. Bias can be minimized by scientists
3. Environmental phenomena involve interacting variables
and complex interactions
4. Statistical methods may be used to estimate very large or
very small numbers
5. Scientific process is limited to the natural world
Science Focus: Statistics and
Probability
• Statistics
• Collect, organize, and interpret
numerical data
• Probability
• The chance that something will
happen or be valid
• Need large enough sample size
Matter Consists of Elements
and Compounds• Matter
• Has mass and takes up space
• Elements
• Unique properties
• Cannot be broken down
chemically into other substances
• Molecule
• Two or more atoms of the same
or different elements held
together by chemical bonds
• Compounds
• Two or more different elements
bonded together in fixed
proportions
Atoms and Molecules
Matter: occupies space and has mass. Mass: measure of the amount of matter it contains. Atom: smallest particle that can contain the chemical properties of an element. Composed of electrons, neutrons, and protons. Element: composed of atoms that cannot be broken down further. Atomic Number: number of protons in the atom’s nucleus. Mass Number: total number of protons and neutrons in an element.
Elements important to the Study of
Environmental ScienceHydrogen Bromine
Carbon Sodium
Oxygen Calcium
Nitrogen Lead
PhosphorusMercury
Sulfur Arsenic
Chlorine Uranium
Flourine
Radioactivity
Isotopes: An atom with the same number of protons but the number of neutrons varies. Radioactive Decay: spontaneous release of material from the nucleus. Half Life: the time it takes for one-half of the original radioactive parent atoms to decay.
Compounds Important to the Study of
Environmental Science
Sodium Chloride – NaCl
Carbon Monoxide – CO
Carbon Dioxide – CO2
Nitric Oxide – NO
Nitrogen Dioxide – NO2
Nitrous Oxide – N2O
Nitric Acid – HNO3
Methane – CH4
Glucose – C6H12O6
Water – H2O
Hydrogen Sulfide –H2S
Sulfur Dioxide – SO2
Sulfuric Acid – H2SO4
Ammonia – NH3
Compounds Important to the Study of
Environmental Science
Atoms, Ions, and Molecules Are the Building Blocks of Matter
• Atomic theory
• All elements are made of atoms
• Subatomic particles
• Protons with positive charge and neutrons with no charge in nucleus
• Negatively charged electrons orbit the nucleus
• Atomic number
• Number of protons in nucleus
• Mass number
• Number of protons plus neutrons in nucleus
Model of a Carbon-12 Atom
Fig. 2-5, p. 39
Atoms, Ions, and Molecules Are the Building Blocks of Matter
• Isotopes
• Same element, different number of neutrons
• Ions
• Gain or lose electrons
• Form ionic compounds
• pH
• Measure of acidity
• H+ and OH-
Ions Important to the Study of Environmental Science
Hydrogen - H+
Sodium – Na+
Calcium – Ca2+
Aluminum – Al3+
Ammonium – NH4+
Chlorine – Cl-
Hydroxide – OH-
Nitrate – NO3-
Sulfate – SO42-
Phosphate – PO43-
Acids, Bases and pH
• Acid- a substance that contributes hydrogen ions to a solution
• Two important acids that are found in acid rain are: nitric acid (HNO3) and sulfuric acid (H2SO4)
• Base- a substance that contributes hydroxide ions to a solution; can be used to neutralize acids. Ex: NaOH, and Ca(OH)2
• Most acids and bases dissolve in water
The pH Scale
• The pH scale is used to indicate the strength of acids and bases. The scale is numbered 1-14. 1= strongest acid. 14= strongest base
• Water is neutral or 7
pH Scale
Supplement 5, Figure 4
Loss of NO3− from a Deforested Watershed
Fig. 2-6, p. 40
Organic Compounds Are the Chemicals of Life
• Organic compounds
• Hydrocarbons and chlorinated hydrocarbons
• Simple carbohydrates
• Macromolecules: complex organic molecules
• Complex carbohydrates
• Proteins
• Nucleic acids
• Lipids
• Inorganic compounds
Amino Acids and Proteins
Supplement 4, Fig. 8
Nucleotide Structure in DNA and RNA
Supplement 4, Fig. 9
Fatty Acid Structure and Trigyceride
Supplement 4, Fig. 11
Matter Comes to Life through Genes, Chromosomes, and Cells
• Cells: fundamental units of life; all organisms are composed of one or more cells
• Genes
• Sequences of nucleotides within DNA
• Instructions for proteins
• Create inheritable traits
• Chromosomes: composed of many genes
Cells, Nuclei, Chromosomes, DNA, and Genes
Fig. 2-7, p. 42
Some Forms of Matter Are More Useful than Others
• High-quality matter
• Highly concentrated
• Near earth’s surface
• High potential as a resource
• Low-quality matter
• Not highly concentrated
• Deep underground or widely dispersed
• Low potential as a resource
• Material Efficiency (Resource productivity) – total amount of material needed to produce each good
Examples of Differences in Matter Quality
Fig. 2-8, p. 42
2-3 What Happens When Matter Undergoes Change?
• Concept 2-3 Whenever 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
Changes• Physical change
• No change in chemical composition
• Chemical change, chemical reaction
• Change in chemical composition
• Reactants and products
• Nuclear change
• Natural radioactive decay
• Radioisotopes: unstable
• Nuclear fission
• Nuclear fusion
Types of Nuclear Changes
Fig. 2-9, p. 43
We Cannot Create or Destroy Matter
• Law of conservation of matter
•Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed
2-4 What is Energy and What Happens When It Undergoes Change?
• 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 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- the ability to do work or transfer heat
• All energy can trace its origin back to the sun.
• The sun gives off EM radiation that includes:
• Visible light, UV light, and infrared energy (heat).
• EM radiation is carried by photons(packets of energy)
• Quantity of energy carried by the photon depends on its wavelength.
The Electromagnetic Spectrum
Fig. 2-11, p. 45
Energy Comes in Many Forms
• Energy Capacity to do “work” and transfer heat
• Sun provides 99% of earth’s energy
• Warms earth to comfortable temperature
• Plant photosynthesis
• Winds
• Hydropower
• Biomass
• Fossil fuels: oil, coal, natural gas
Energy Comes in Many Forms
Energy is measured in joules.Energy: the ability to do work. Power: rate at which work is done. Kinetic Energy: energy of motion.
Potential Energy: energy
stored but not released.
Chemical Energy: potential
energy in chemical bonds.
Some Types of Energy Are More
Useful Than Others• High-quality energy
• High capacity to do work
• Concentrated
• High-temperature heat
• Strong winds
• Fossil fuels
• Low-quality energy
• Low capacity to do work
• Dispersed
Ocean Heat Is Low-Quality Energy
Energy Changes Are Governed by Two Scientific Laws
• First Law of Thermodynamics
• Law of conservation of energy
• Energy is neither created nor destroyed in physical and chemical changes
• Second Law of Thermodynamics
• Energy always goes from a more useful to a less useful form when it changes from one form to another
• Light bulbs and combustion engines are very inefficient: produce wasted heat
First Law of Thermodynamics: Energy is Conserved
Energy is neither created nor destroyed.
When energy is transformed, the quantity of energy remains the same but its ability to do work diminishes.
Energy Efficiency: the ratio of the amount of work that is done to the total amount of energy that is introduced into the system.
Energy Quality: the ease at which an energy source can be used for work. Wood vs Gasoline
Second Law of Thermodynamics
Energy-Wasting Technologies
Fig. 2-16a, p. 48
2-5 What Are Systems and How Do They Respond to Change?
• Concept 2-5 Systems have inputs, flows, and outputs of matter and energy, and feedback can affect their behavior.
System – a set of components that function and interact in some regular way.
Most systems have the following key components:
Inputs from the environment
Flows or throughputs of matter and energy within the system at certain rates
Outputs to the environment
What are Systems and how do they respond to change?
Open vs. Closed Systems
• Most systems are open, where matter and energy exchanges occur across boundaries.
• Examples: the ocean receives energy from the sun which is transferred to plants and algae. Energy and matter are transferred back to the atmosphere from the ocean.
• Earth is a closed system due to its gravitational field. Little matter enters or leaves it.
• Calculating inputs and outputs tell us about systems. When they are equal➔steady state
Inputs, Throughput, and Outputs of an Economic System
Fig. 2-17, p. 48
Feedback Loops
Feedback – any process that increases or decreases a
change to a system.
Feedback Loop – when an output of matter, energy, or
information is feed back into the system as an input and
leads to changes in that system.
Positive Feedback Loop – system changes further in
the same direction. (Decreasing Vegetaion in a valley)
Can cause major environmental problems
Negative Feedback Loop – system changes in the
opposite direction. (Your thermostat at home)
Positive Feedback Loop
Fig. 2-18, p. 49
Positive feedback loop
Negative Feedback Loop
Fig. 2-19, p. 50
Negative feedback loop
Time Delays Can Allow a System to Reach a Tipping Point
• Time delays vary
• Between the input of a feedback stimulus and the response to it
• Tipping point, threshold level
• Causes a shift in the behavior of a system
• Melting of polar ice
• Population growth
System Effects Can Be Amplified through Synergy
• Synergistic interaction, synergy
• Two or more processes combine in such a way that combined effect is greater than the two separate effects
• Helpful
• Studying with a partner
• Harmful
• E.g., Smoking and inhaling asbestos particles
The Usefulness of Models for Studying Systems
1. Identify major components of systems and interactions within system, and then write equations
2. Use computer to describe behavior, based on the equations
3. Compare projected behavior with known behavior
• Can use a good model to answer “if-then“ questions
