Chapter 2
Science, Systems,
Matter, and Energy
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.
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)).
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).
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.
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
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
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
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
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.