Transcript APES-Chapter-3

Chapter 3
Science, Systems, Matter, and
Energy
Objectives
Science as a process for understanding
Components and regulation of systems
Matter: forms, quality, and how it
changes; laws of matter
Energy: forms, quality, and how it
changes; laws of energy
Science
 Scientific Data
 Hypothesis – based on
observations
 Scientific Theories verified, widely
accepted hypothesis
 Scientific Laws happens over and over
in nature
(Thermodynamics)
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
Scientists Use Reasoning
 Inductive
- specific observations to arrive at a general
conclusion
Example: drop several objects and conclude that all
objects fall to the earth’s surface when dropped
 Deductive
- generalizations to arrive at a specific conclusion
Example: all birds have feathers, therefore eagles
have feathers
Two Types of Science
 Frontier Science
- not widely tested and accepted
Example: herbal remedies
 Consensus Science
- widely accepted by expert scientists
Example: gravity, thermodynamics, etc.
Systems
 Set of components that …
1. function and interact in a predictable
manner.
2. can be isolated for observation.
 Components of systems are …
1. Inputs – what is put into the system.
2. Flows – what is within the system.
3. Stores – what is accumulating within the
system.
4. Outputs – what flows out of the system.
How are Systems Regulated?
 Positive Feedback
- Change in one direction causes further
change in the same direction.
Example: money in the bank accumulating
interest
 Negative Feedback
- Change leads to lessening of that change.
Example: recycling aluminum cans
How do Time Delays affect
Systems?
 Can allow a problem to build up slowly until it
reaches a threshold.
 Can cause a fundamental shift in the system.
 Examples:
- leak from toxic waste dump
- lung cancer 20 years after smoking cessation
How can Synergy affect Systems?
 Synergy
1 + 1 = 3?
- Combined affect is more than the sum
of their separate effects.
- Example: Moving a 300 lb. log
Person 1 = 100 lbs.
Person 2 = 100 lbs.
Matter: Forms, Structure, and Quality
■ Element:
building blocks of matter
■ Compound:
two or more elements
combined
■ Atom:
smallest units of matter
■ Ion:
charged atom
■ Molecule:
two or more atoms combined
What’s in an Atom?
 Protons
+ positive charge
 Neutrons
no charge
 Electrons
- negative charge
 Atomic Number
number of protons
Examples of Atoms
Fig. 3-4 p. 48
Chemical Bonds
Covalent –
“sharing”
Chemical Bonds
Ionic “transfer
of
electrons”
Organic Compounds
 Hydrocarbons – natural gas (CH4)
 Chlorinated Hydrocarbons –
DDT (C14H9Cl5)
 Chlorofluorocarbons – aerosals
and AC Coolant
 Carbohydrates – glucose, sucrose,
fructose, galactose
 Proteins – amino acids with
carbon backbones
The Four States of Matter
Solid
Liquid
Gas
Plasma
Which State of Matter is the Most
Abundant?
 Plasma
- sun and stars
- high energy mix of + and –
particles
- formed when electrons are taken
from the nuclei of atoms (high
energy process)
Matter
 Matter Quality
- Measure of how useful a form of matter
is to us as a resource, based on its
availability and concentration.
 High Quality Matter
1. Fairly easy to extract and
concentrated.
2. Found near the Earth’s surface.
3. Great potential for use as a
resource.
Matter Continued
 Low Quality Matter
1. Dilute
2. Deep underground or dispersed in
the ocean (difficult to extract).
3. Little potential use as a resource.
 Material Efficiency
- Amount of material needed to produce
each unit of goods or services.
Forms of Energy
 Kinetic
- energy in motion
Examples: Wind, Flowing Streams,
Electricity
 Potential
- stored energy
Examples: Unlit Stick of Dynamite,
Rock in Hand
Transfer of Heat Energy
Convection
Heating in the bottom of a pan
causes the water to vaporize
into bubbles. Because they
are lighter than the
surrounding water, they rise.
Water then sinks from the
top to replace the rising
bubbles. This up and down
movement (convection)
eventually heats all of the
water.
Conduction
Heat from a stove burner
causes atoms or molecules in
the pan’s bottom to vibrate
faster. The vibrating atoms or
molecules then collide with
nearby molecules, causing
them to vibrate faster.
Eventually, molecules or
atoms in the pan’s handle are
vibrating so fast it becomes
too hot to touch.
Radiation
As the water boils, heat from
the hot stove burner and pan
radiates into the surrounding
air, even though air conducts
very little heat.
Energy
Energy Quality
- Energy source’s ability to do useful
work.
 High Quality Energy
1. Concentrated
2. Provides useful work
Examples: Electricity, Concentrated
Sunlight

Energy Continued
 Low Quality Energy
1. Dispersed
2. Little useful work
Example: Heat dispersed in the
Atlantic Ocean.
Why is There No “Away”?
Law of Conservation of Matter
 We cannot destroy atoms.
 We can only rearrange them
into different spatial
patterns (physical) or
into different
combinations
(chemical).
 Everything we think we have
“thrown away” is still here in one
form or another.
Example
 DDT
- banned, but still residues in imported
coffee, tea, fruit, and other foods.
- or as fallout from air masses moved long
distances by wind.
 Law of Conservation of Matter
- means we will always face the problem
of what to do with wastes and pollutants.
Pollution
3 Factors that Determine the Severity of a Pollutant’s
Chemical Effects:
1. Chemical Nature
2. Concentration
- parts per million (ppm)
3. Persistence
- measure of how long the pollutant stays in the air,
water, soil, or body.
Classification of Pollutants:
1. Degradable (reduced to acceptable levels)
2. Slowly Degradable (decades or longer-DDT)
3. Nondegradable (natural processes cannot break down -lead,
arsenic)
Nuclear Changes
 Matter undergoes a nuclear change:
1. natural radioactive decay
2. nuclear fission
3. nuclear fusion
Natural Radioactive Decay
 A nuclear change in which unstable
isotopes spontaneously emit fastmoving particles (matter), high-energy
radiation, or both at a fixed rate.
 Unstable Isotopes are called “radioactive
isotopes” - radioactive decay continues
until isotope becomes stable.
 Isotopes have a different number of
neutrons but the same number of
protons.
Natural Radioactive Decay
Continued
 Radiation emitted by radioisotopes is
damaging ionizing radiation.
 Gamma Rays – a form of high-energy
electromagnetic radiation emitted from
radioisotopes. You do not want to be
exposed to these waves.
 Alpha/Beta Particles – high-speed
ionizing particles emitted from the
nuclei of radioisotopes.
What is Half-Life?
The amount of time needed for one-half of
the nuclei in a given quantity of a
radioisotope to decay and emit their
radiation to form a different isotope.
 Decay continues, often producing a series of
different radioisotopes, until a stable,
nonradioactive isotope is formed.
 The half-life estimates how long a sample of
radioactive isotope must be stored in a
safe container before it decays to a safe
level and can be released into the
environment.

Half-Life Continued
 A general rule is that such decay to a safe level
takes about 10 half-lives.
 Example: Plutonium-239 has a half-life 24,000
years. It is produced in nuclear reactors and
used in nuclear weapon production. It must
be stored safely for 240,000 years (10 x
24,000).
 Plutonium-239 can cause lung cancer when its
particles are inhaled in minute amounts.
 Ionizing radiation exposure from alpha particles,
beta particles, and gamma rays can damage
cells by genetic damage (mutations of DNA)
or somatic damage (tissue damage).
Nuclear Fission
 Neutrons can split apart the nuclei of certain
isotopes with large mass numbers and
release a large amount of energy.
1. Neutron hits the nucleus of an isotope.
2. Nucleus splits and releases 2 or 3 more
neutrons and ENERGY.
3. Each of these neutrons can go on to cause
additional fission.
 Multiple fissions create a chain reaction which
releases an ENORMOUS AMOUNT OF
ENERGY.
Examples of Nuclear Fission
 Atomic Bomb – An enormous amount of
energy is released in a fraction of a second
in an uncontrolled nuclear fission chain
reaction.
 Nuclear Power Plant – The rate at which the
nuclear fission chain reaction takes place
is controlled. In conventional nuclear
fission reactors, the splitting of uranium235 nuclei releases energy in form of heat,
which produces high-pressure steam to
spin turbines and thus generate
electricity.
Nuclear Fusion
 Nuclear fusion is a nuclear change in which
extremely high temperatures force the nuclei
of isotopes of some lightweight atoms to fuse
together and form a heavier nucleus which in
turn releases large amounts of energy.
 Extremely high temperatures (at least 100 million
oC) are needed to force the positively
charged nuclei (protons strongly repel one
another) to fuse.
 Source of energy in sun and stars.
Sun-hydrogen isotopes fuse to make helium-energy and heat.
What are Nuclear Reactions
used for?
 Energy Production: nuclear power
plants generate electricity for our
homes.
 Medical Technology: cancer treatment,
X-rays.
 Nuclear Weapons: atomic bomb,
hydrogen bomb.
Nuclear Power Plant
Atomic Bomb
Laws of Thermodynamics
FIRST LAW OF THERMODYNAMICS
 In all physical and chemical changes, energy is
neither created nor destroyed, but it may be
converted from one form to another.
 Energy input always equal energy output.
 You cannot get something for nothing in terms of
energy quantity.
SECOND LAW OF THERMODYNAMICS
 When energy is changed from one form to another,
some of the useful energy is always degraded to
lower quality, more dispersed, less useful energy,
usually heat.