Download Science, Systems, Matter, and Energy

Living in the Environment
16th Edition
Chapter 2
Science, Systems, Matter,
and Energy
Key Concepts
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
Nuclear changes and radioactivity
Science, and Critical Thinking
 Scientific data
Ask a question
 Facts
 Scientific hypothesis
 Explanation of what is
observed in nature
 Scientific (natural) laws
 Scientific theories
 Consensus science
 Data, theories, and laws
that widely accepted by
the scientific community
 Frontier science
 Preliminary results
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
Scientific Method
Make Observations
Formulate a Hypothesis
Test Hypothesis
Collect Data
Interpret Data
Draw Conclusions
Controlled Experiment
(Single Variable Analysis)
• Experimental Group
– Variables change in a known way
– Independent variable
– Dependent Variable
• Control Group (Controls)
– Variables are not changed
• Controls
• Constants
• Data
– Quantitative - numbers
– Qualitative - descriptions
Types of Reasoning
• Inductive reasoning
– Using specific
observations and
measurements to arrive
at a general conclusion
– bottom-up reasoning
• Deductive reasoning
– Reasoning that goes
from the general to the
specific
– top-down reasoning
Models and Behavior of Systems
System – a set of components that
1) function in a regular and predictable
manner
2) can be isolated for observation and
study
Models and Behavior of Systems
• Inputs
– matter, energy, information
• Flows
– throughputs of matter, energy, or information
at certain rates
• Stores
– storage areas for matter, energy or information
• Outputs
– Form of matter, energy, or information that
flow out of the system and into sinks in the
environment
Models
Approximate representations or simulations of real
systems to
– find out how systems work
– evaluate which ideas or hypotheses work
• Mental models – what do you think
• Mathematical models – one or more equations
– To describe the behavior of a system
– Make predictions about the behavior of a system
• Conceptual models
– Qualitative
• Numerical models
– Computer simulations
System Regulation
Feedback loop – when output of matter, energy, or
information is fed back into the system as an
input that changes the system.
• Positive Feedback – causes change in the same direction
• Negative Feedback – one change leads to a lessoning of that
change.
Coupled loops
System Regulation
• Homeostasis – maintenance of a favorable internal
condition of a system despite external changes.
• Time Delay – delay in expected effect
• Synergy – the combined effect of two or more
processes is greater than the sum of the separate
effects
Matter: Forms, Structure, and Quality
• Elements
– Building blocks of matter
• Compounds
– Two or more different
elements held together by
chemical bonds
• Mixtures
– Combinations of various
elements, compounds, or
both
• Molecules
– Two or more atoms of the
same or different elements
held together by chemical
bonds
– Example: O2
Atom – the smallest unit of matter that
is unique to a particular element.
Subatomic Particles
• Protons
– Positively charges
• Neutrons
– uncharged
• Electrons
– Negatively charged
Atomic Characteristics
• Atomic Number
– Number of protons in the nucleus
• Atomic Mass
– Number of protons and neutrons
• Ions
– Atoms that have lost or gained electrons
• Isotopes
– Forms of a element having the same atomic
number but a different mass number
– Identified by attaching their mass number to
their name
– U235
Examples of Atoms
Chemical Bonds
• Chemical formulas show the
number of atoms of each
type in a compound
– Contains symbol for each
element
– Uses subscripts to
represent the number of
atoms
• Ionic bonds
– Bonds between oppositely
charged ions
– NaCl (Na+ and Cl-)
Chemical Bonds
• Covalent bonds –
bonds between
uncharged atoms
– H2O
• Hydrogen bonds
– Weak attraction
between molecules
of covalent
compounds
Organic vs Inorganic Compounds
Organic compounds
–contain carbon atoms
–Held together by covalent bonds
• Hydrocarbons
– Carbon and hydrogen
– methane (CH3)
• Chlorinated hydrocarbons
– Carbon, hydrogen, and chlorine
– DDT (C14H9Cl5)
• Chlorofluorocarbons (CFCs)
– Carbon, chlorine, and flourine
– freon (CCl2F2)
Organic Compounds
• Simple carbohydrates
– Carbon, hydrogen, oxygen
– Simple sugars (C6H12O6)
• Complex carbohydrates
– Two or more simple sugars hooked together
• Proteins
– Monomers of amino acids linked together
Genetic Material
•Nucleic Acids
DNA and RNA
•Genes – specific sequence
of nucleotides in a DNA
molecule
Organic vs Inorganic Compounds
Inorganic compounds
– Lack carbon-carbon or carbonhydrogen covalent bonds
– NaCl, H2O, N2O, CO2, NH3
The Four States of Matter
Solid
Liquid
Gas
Plasma
The Four States of Matter
Plasma
 high energy mixture of
positively charged ions and
negatively charged electrons
 sun, stars, lightening
Matter Quality and Material Efficiency
• High-quality matter
– Concentrated
– Near the earth’s surface
– Great potential for use
• Low-quality matter
– Dilute
– Deep underground
– Little potential as a resource
• Material efficiency
(resource productivity)
– Total amount of material
needed to produce each unit
of goods and services
Energy: What is it?
The capacity to do work
and transfer heat.
Work = force x
distance
Energy: Forms
• Kinetic energy
– Energy contained in moving objects
– Wind, streams, electricity
• Potential energy
– Stored energy
– Stick of dynamite, water behind a dam
Electromagnetic radiation
Energy radiated in the form of waves as a result
of changing electric and magnetic fields
Heat Energy
• Heat
– The total kinetic energy of all the
moving atoms, ions, or molecules
within a given substance
• Temperature
– Average speed of motion of the atoms,
ions, or molecules in a sample of matter
at a given moment
Transfer of Heat Energy
Convection
Conduction
Heating water in the bottom of a pan
causes some of 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.
Radiation
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 atoms or 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.
As the water boils, heat from the hot
stove burner and pan radiate into the
surrounding air, even though air
conducts very little heat.
Energy: Quality
 High-quality
energy
concentrated
 Low-quality
energy
dispersed
Physical and Chemical Changes
The Law of Conservation of Matter:
matter is neither created nor destroyed
Matter is not consumed
Matter only changes form
There is no “away”
How harmful are pollutants?
1) Chemical nature of pollutants
2) Concentration
3) Persistence
– Degradable (nonpersistent) pollution
•
Broken down completely by natural, chemical or
biological processes
– Slowly degradable (persistent) pollution
•
•
May take decades or longer
DDT
– Nondegradable pollutants
•
•
Cannot be broken down
Lead, mercury, arsenic
Nuclear Changes –
nuclei of isotopes spontaneously change
1) Natural radioactive
decay
•
Unstable isotopes
spontaneously emit
fast-moving
particles, high
energy radiation, or
both at fixed rates
•
“radioisotopes”
•
Damaging “ionizing”
radiation
Ionizing Radiation
1) Gamma rays
•
High-energy
electromagnetic
radiation
2) Alpha particles
•
Fast moving,
positively charged
chunks of matter
3) Beta particles
•
High speed electrons
Ionizing Radiation: Effects
•
Genetic Damage
•
•
Mutations or changes
in DNA that alter
genes and
chromosomes
Somatic Damage to
tissue
•
Burns, eye cataracts,
certain cancers
Nuclear Changes
Radioactive Decay
• Radioactive isotopes decay at
a characteristic fixed rate
called a half-life (t1/2)
– Time for half the nuclei in a
sample to decay
– Can’t be changed due to T,
P, or chemical rxns
– Used to estimate time a
sample of radioisotope
must be stored safely
before it decays to a safe
level half-life X 10
Radioactive Decay and Half-life
• Time needed for onehalf of the nuclei in a
radioisotope to emit
its radiation (decay)
• Characteristic half-life
for each radioisotope
• General rule:
radioisotopes must be
stored for 10 half-lives
Half-Lives of Selected Radioisotopes
Isotope
Radiation
Half-Life
Emmitted
Potassuium42
12.4 hrs
Alpha, beta
Iodine-131
8 days
Beta, gamma
Colbalt-60
5.27 yrs
Beta, gamma
Hydogren-3
tritium
12.5 yrs
Beta
Strontium-90
28 yrs
Beta
Carbon-14
5,370 yrs
Beta
Plutonium-239
24,000 hrs
Alpha, gamma
Uranium-235
710 million yrs
Alpha, gamma
Uranium-238
4.5 billion yrs
Alpha, gamma
Nuclear Reactions
Fission
Fusion
Nuclear Changes
Nuclear Fission
• Fission—splitting of nuclei
– Nuclei of isotopes with
large masses split into
lighter nuclei when struck
by neutrons
– Release energy and more
neutrons setting off a
chain reaction
– Atomic bomb and nuclear
power plants
235
92 U
n
92
36 Kr
n
235
92 U
92
36 Kr
235
92 U
n
n
141 Ba
56
n
92 Kr
36
n
n
n
n
235
92 U
n
141
56 Ba
141 Ba
56
92 Kr
n
36
235
92 U
n
141 Ba
56
23
5 U
92
n
235
92 U
Nuclear Changes
Nuclear Fusion
• Fusion—joining of nuclei
– Isotopes of light elements are
forced together at high T’s until
they fuse into a heavier nucleus
• Harder to accomplish than
fission, but releases more
energy
• Fusion of H nuclei to form He
nuclei is a source of energy
for sun and stars
• H bombs
Fuel
Reaction Conditions
Products
D-T Fusion
Neutron
+
Hydrogen-2 or
deuterium nucleus
+
Hydrogen-3 or
tritium nucleus
+ Proton
Neutron
+
+
100 million ˚C
Energy
+
+
Helium-4
nucleus
Laws Governing Energy Changes
First Law of Thermodynamics (Energy)
 Energy is neither created nor destroyed
 Energy only changes form
 You can’t get something for nothing
ENERGY IN = ENERGY OUT
Laws Governing Energy Changes
Second Law of Thermodynamics
 In every transformation, some energy is
converted to heat
 You cannot break even in terms of
energy quality
Solar
energy
Waste
heat
Mechanical
energy
(moving,
thinking,
living)
Chemical
energy
(food)
Chemical
energy
(photosynthesis)
Waste
heat
Waste
heat
Waste
heat
Connections: Matter and Energy Laws
and Environmental Problems
 High-throughput (waste) economy
 Matter-recycling economy
 Low-throughput
economy