Transcript Chapter 2

MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
17TH
CHAPTER 2
Science, Matter, Energy,
and Systems
Monday, 9.21
• Purchase Knob
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 with one that had been stripped.
• What type of study is this? Explain.
• Is there a control? Why is it needed?
• Stripped site:
• 30-40% more runoff
• More dissolved nutrients
• More soil erosion
The Effects of Deforestation on the Loss
of Water and Soil Nutrients
Fig. 2-1, p. 31
Loss of NO3− from a Deforested Watershed
Fig. 2-6, p. 40
A few study topics …
• What are the three Principles of Sustainability?
• By the way, what is sustainability?
• Describe the Tragedy of the Commons.
• Reading guide: No activity yet!
• Important Laws:
• Law of Conservation of Matter
• First and Second Laws of Thermodynamics
• Why are these important in APES?
• Feedback Loops
2-1 What Do Scientists Do?
• Concept 2-1 Scientists collect data and develop
theories, models, and laws about how nature
works.
The Scientific Process
• You observe that all of the fish in
a pond have disappeared.
Describe how you might use the
scientific process to determine
the cause of this fish kill.
Fig. 2-2, p. 33
Characteristics of Science and Scientists
•
•
•
•
•
•
•
Curiosity
Skepticism
Reproducibility
Peer review
Openness to new ideas
Critical thinking
Creativity
• What do these mean to us with respect to science
and scientists?
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
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
Compounds
• Matter
• Has mass and takes up space
• Elements
• Unique properties
• Cannot be broken down chemically into other
substances
• Compounds
• Two or more different elements bonded together
in fixed proportions
Chemical Elements Used in The Book
Table 2-1, p. 38
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
Chemical Ions Used in This Book
Table 2-2, p. 40
Compounds Used in This Book
Table 2-3, p. 40
Organic Compounds Are the
Chemicals of Life
• Organic compounds contain at least two carbon atoms
combined with atoms of one or more other elements.
[One exception is methane, CH4, which is still
considered to be an organic compound.]
• Hydrocarbons and chlorinated hydrocarbons
• Simple carbohydrates
• Macromolecules: complex organic molecules
•
•
•
•
Complex carbohydrates
Proteins
Nucleic acids
Lipids
• Inorganic compounds are all other compounds.
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
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
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.
• This means that we can never really throw
anything “away,” because the atoms in any form
of matter cannot be destroyed as it undergoes
physical or chemical change.
• We can burn trash, but we end up with ash we
must deal with and gases that can pollute the air.
Law of conservation of matter—
A question:
• If there is no “away” where organisms can get rid
of their wastes because of this law, why is the
world not filled with waste matter?
Explain how the Law of Conservation of
Matter applies in a forest fire.
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 comes in many forms.
• Kinetic energy
• Flowing water
• Wind
• Heat
• Transferred by radiation, conduction, or convection
• Electromagnetic radiation
• Potential energy
• Stored energy
• Can be changed into kinetic energy
Wind’s Kinetic Energy Moves This Turbine
Fig. 2-10, p. 44
Potential Energy
Fig. 2-12, p. 45
Energy comes in many forms. (cont.)
• Sun provides 99% of earth’s energy
•
•
•
•
•
•
Warms earth to comfortable temperature
Plant photosynthesis
Winds
Hydropower
Biomass
Fossil fuels: oil, coal, natural gas
Fossil fuels
Fig. 2-14a, p. 46
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
Fig. 2-15, p. 47
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.
• They produce wasted heat.
Energy-Wasting Technologies
Fig. 2-16a, p. 48
First and Second Laws of Thermo
• Once a gallon of
gasoline is burned in
a car (high-quality
energy), the
concentrated energy
in the gasoline is
degraded to lowquality heat that is
dispersed into the
environment at a low
temperature.
• What else is released?
Critical Thinking …
• Imagine that you have the power to violate the
first law of thermodynamics for one day.
• What are three things you would do with this
power? Explain your choices.
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.
Systems Have Inputs, Flows,
and Outputs
• System
• Set of components that interact in a regular way
• Human body, earth, the economy
• Inputs from the environment
• Flows, throughputs of matter and energy
• Outputs to the environment
Fig. 2-17, p. 48
Systems Respond to Change
through Feedback Loops
• Feedback in general is the process in which changing
one quantity changes a second quantity, and the change
in the second quantity in turn changes the first. Positive
feedback amplifies the change in the first quantity while
negative feedback reduces it.
• Positive feedback loop
• Causes system to change further in the same
direction
• Can cause major environmental problems
• Negative, or corrective, feedback loop
• Causes system to change in opposite direction
A quick video …
• Positive Feedback Loops
Negative Feedback, cont.
Positive Feedback Loop
Fig. 2-18, p. 49
Global Warming—Positive
Feedback Loop
• Atmospheric temperatures
rise, causing melting of the
polar ice. As the ice melts,
there is less of it to reflect
sunlight, and more water that
is exposed to sunlight. Water
absorbs more solar energy
than ice, making the polar
areas warmer, and causing the
ice to melt faster … thus
exposing more water to absorb
more solar energy …
Negative Feedback Loop
Fig. 2-19, p. 50
Negative Feedback
• If the number of prey decreases in an
ecosystem, then some predators starve, and
their numbers decrease.
• What negative feedback responses can you
think of with respect to the human body?
Positive or Negative Feedback?
• A warming atmosphere can evaporate more
water, forming clouds. Clouds block some solar
heat, which reduces the evaporation.
• Lake level drops, which reduces the lake surface
area, leading to less evaporation, causing the
level in the lake to rise.
• Population increases, leading to more births,
which is a population increase, which leads to
more births …
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