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APES Chapter #3
Science, System, Matter
and Energy
Nature of Science

Science- an organized way
of using evidence to learn
about the natural world
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Observations
Hypothesis
Experiment
Results
Conclusion
Scientific Method
Observations and Hypothesis
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1.Observations/Questions
 What you see
 Inferences-logical interpretations of
what you see.
 Questions then arise…….
2.Hypothesis-scientific and testable
explanation for observations
“If……then……”
Scientific Method
Experimental Procedure

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3.Experimental procedure- test the
hypothesis
Must be controlled, reproducible
Testing effects of
only one variable
(factor in experiment
that is subject to
change)
Other scientists
need to be able to
reproduce and
prove valid.
Scientific Method
Experimental Procedure

Subjects you are testing are split into groups:
 Experimental Group-given the experimental
factor
 Control Group:-what you’re comparing
experimental group to.
Experimental Group
Fertilizer
Control Group
No Fertilizer
Scientific Method
Experimental Procedure

Testing ONE variable while keeping
others the same
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Independent (manipulated) variablefactor in experiment that’s purposely
changed—????
Dependent (responding) variable —factor
that a scientist observes for responses
(changes) in—????
Scientific Method
Results and Conclusion
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4. Results
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Record data—tables, graphs
Qualitative data- physical traits (qualities)
described
Quantitative data- measurements
(quantities)
5.Conclusions
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Hypothesis is either supported or
rejected. NEVER “PROVEN!”
Can be partly true
Findings always useful!!!
Scientific Method
Hypothesis vs. Theory

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Hypothesis- educated, testable explanation for
an observation
Theory
 Verified, credible and widely accepted
hypothesis
 Make future predictions
Law- mathematical description of what a theory
explains
Models and Behavior of Systems
System

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Scientists determine the behavior of a system by
developing a model of it in regards to matter and energy
Set of components that function and interact in regular,
understandable way
Inputs
(from environment)
Energy
Information
Matter
Throughputs
(rates of flow)
Human Body
(inputs may
be stored for
different lengths
of time)
Outputs
(to environment)
Heat
Ideas
and
actions
Waste
and
pollution
Models and Behavior of Systems
Feedback Loops

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Feedback loops are found in a system
Output fed back into system leads to changes
 Positive feedback- AMPLIFICATION
 i.e. global warming
 Negative feedback- CORRECTIVE
 System changes in opposite direction
 i.e. thermostat in house
 crime and punishment
Models and Behavior of Systems
Time Delays and Synergy
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Time delays -delay b/t input and
output
 Allows problems to build
slowly so corrective action
may come too late
 i.e. smoking and population
Synergy- 2 or more processes
interact so their combined effect
is > than the sum of separate
effects
 i.e. drugs and alcohol,
people picking up object
Matter
Atoms
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Matter-anything that has mass and
takes up space
Atom--basic unit of matter
 Protons—positive, nucleus
 Neutrons—neutral, nucleus
 Electrons—negative, orbits
Matter
Parts of Atoms
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Protons and Neutrons
 Together make up an atom’s
atomic mass.
Electrons
 1/1840 of the mass of p’s and n’s
 Moving in orbitals surrounding
the nucleus
 Responsible for chemical
properties of atoms (how they
react)
 Atoms--Something to Think
About!
Matter
Elements
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Element-pure substance that consists of just one type of
atom
114 in the periodic table
 Atoms have a one or two letter symbol
 Atomic number
 Unique to that element
 #p’s-- and b/c normally atoms
6
are uncharged also = # e’s
 Atomic mass
 How much mass an atom has
 #p’s + #n’s
C
Carbon
12.011
6
Matter
Isotopes
Isotopes-atoms of the same element with different # of
neutrons
Atomic number same, atomic mass different
Isotopes of Carbon
Nonradioactive carbon-12
6 electrons
6 protons
6 neutrons
Nonradioactive carbon-13
6 electrons
6 protons
7 neutrons
Radioactive carbon-14
6 electrons
6 protons
8 neutrons
Matter
Radioactive Isotopes

Radioactive isotopes- atoms with unstable
nuclei
 Break down at constant rate and can
give off dangerous radiation (type of
energy)
 Beneficial uses:
 C-14 dating can help geologists date
fossils
 Cancer treatment
 U-235 in nuclear reactors
Matter
Bonding
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Bonding- atoms gain, lose, or share e’s to be stable
Compound- formed by chemical combination of 2 or more
elements
Bond formation involves outermost e’s
Two types of bonds
 Ionic
 Covalent
Chemical Bonds
Ionic bonds
•Ionic bond -one or more e’ are transferred
•Results in formation of ions, or charged atoms that attract to
form an ionic compound
Sodium atom (Na)
Chlorine atom (Cl) Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Chemical Bonds
Covalent Bonds

Covalent bonds- formed by atoms
sharing valence electrons
 Stronger than ionic bonds
 Molecule--forms when atoms
are joined in a covalent bond
Compounds
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Organic- contain C-C bonds
Can also have H, O, P, S, N and
others
Natural or synthetic
Inorganic- don’t have C-C or CH covalent bonds
NaCl, H2O
C
C
Organic Compounds

Some simple organic molecules can link up, forming C—C
bonds- polymerization
 Amino acids Proteins (meats, enzymes)
 Fatty Acids and glycerol Lipids (fats, oils)
 Sugars  Carbohydrates (sugar, starches)
 Nucleotides Nucleic acids (DNA or RNA)
Inorganic Compounds
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No C-C bonds
Earth’s crust is mostly
inorganic minerals and rock
Various combinations of only
eight elements make up the
bulk of most minerals.
Four States of Matter

Differ in spacing and orderliness of atoms, ions or
molecules
 Solid
 Liquid
 Gas
 Plasma
 Most abundant of all states of matter!
 Forms when enough energy applied to strip away
e’, so it’s a mixture of ions and e’
 Natural forms: sun, stars, lightning and flame
 Artificial forms: TV, neon signs
Matter Quality

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High quality
 Easily accessible
 High concentration
 Great potential for use as resource
Low quality
 Deep underground or difficult to
collect
 Low concentration
 Low potential as a resource
High Quality
Low Quality
Solid
Gas
Salt
Solution of salt in water
Coal
Coal-fired power
plant emissions
Gasoline
Automobile emissions
Aluminum can
Aluminum ore
Law of Conservation of Matter
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Physical changes in matter
 Molecules organized
differently but no change
in chemical composition
 Cutting foil, melting water
Chemical changes
 Bonds made or broken
 Burning coal, rusting
Chemical Changes
Reactant(s)
Product(s)
carbon + oxygen
carbon dioxide + energy
CO2 + energy
C + O2
O
C
O
C
O
black solid
colorless gas
colorless gas
O
+ energy
Law of Conservation of Matter
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Law of Conservation of Matter- physical or
chemical changes can’t create or destroy the
atoms involved. They’re just rearranged
Chemical equations must be balanced
No “away”!!!! -Law tells us there will always be
wastes, pollutants, and toxins
Toxicology
Toxicology -the study of the adverse effects of chemicals or
pollutants on living organisms’ health, specifically humans.
Toxicity -a measure of how harmful a substance is and it
depends on:
-Amount of a potentially harmful substance that is
ingested, inhaled, or absorbed through the skin is called
the dose
-Frequency of exposure
-Who is exposed (adult or child)
-How well the body’s detoxification system (liver, kidneys,
etc.) work
© Brooks/Cole Publishing Company / ITP
Toxicology
The resulting type and amount of damage to health are
called the response
Two types of responses:
 Acute- immediate or rapid harmful reaction
(dizziness, rash, death)
 Chronic- permanent or long–lasting consequence
(asthma, kidney damage, heart disease)
Toxicology Factors

Six major characteristics of a substance determines its
toxicity:
 1. Concentration
 1ppm= 1 part pollutant per million parts of gas, solid or
liquid it is in
 Can ↓ pollutant concentration by dumping in larger
volume, but there are limits
 2. Solubility
 Water-soluble- move through the environment and get
in the water supply
 Fat-soluble- penetrate cell membranes and
accumulate in body tissue
Toxicology Factors
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3. Persistence
 Some chemicals are resistant to breakdown so have
long-lasting harmful effects
 Degradable (nonpersistent)—broken down by natural,
physical, chemical or biological processes
 Biodegradable—broken down by living organisms
 Slowly degradable (persistent)
 Decades
 Plastics, DDT
 Nondegrading—lead, mercury, arsenic
Toxicology Factors
• 4. Bioaccumulation results
when the concentration of a
chemical in tissues of an
organism is higher than
would normally be expected.
• 5. Biomagnification
involves magnification of
concentrations as they pass
through the food chains and
webs.
© Brooks/Cole Publishing Company / ITP
Toxicology Factors
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6. Chemical Interactions
 Antagonistic interactions reduce harmful effects
 Vitamin A, D and E apparently reduce some
cancer-causing chemicals
 Synergistic interactions multiplies harmful effects
 Asbestos workers have a 20-fold increased
chance of getting lung cancer, but if they smoke
they have a 400-fold increase
Determining Toxicity
Determining toxicity:
• Case reports (usually to physicians)
• Epidemiology- studies of populations exposed
• Laboratory investigations (usually with test animals)
- LD50 (median lethal dose) -amt of a chemical that kills 50%
of animals (rats) in a test population (60–200 animals) in 2
weeks
- A poison is legally defined as a chemical that has an LD50
≤50 mg chemical/kg body weight
***Higher LD50, less toxic the substance is
Toxicity
Toxicity
Super
Extreme
LD50
Lethal Dose
< 0.01 less than 1 drop
Examples
dioxin, botulism
mushrooms
<5
less than 7 drops
heroin, nicotine
Very
5-50
7 drops to 1 tsp.
morphine, codeine
Toxic
50-500
1 tsp.
DDT, H2SO4, Caffeine
Moderate
500-5K
1 oz.-1 pt.
aspirin, wood alcohol
Slightly
5K-15K
1 pt.
Non-Toxic
ethyl alcohol, soaps
>15K
>1qt.
water, table sugar
***Higher LD50, less toxic the substance is
(LD50 measured in mg/kg of body weight)
Dose–Response Curves
Dose–response curves- show the adverse effects of
various doses of a toxic agent on a test population by
plotting harmful effect as a function of dose.
The left dose–
response curve
shows increasing
harmful effects with
dose, and no dose
is considered safe.
The right example
has a threshold,
such that low doses
are considered safe.
© Brooks/Cole Publishing Company / ITP
Toxicity

Why so little is known of toxicity
 Only 10% of at least 75,000 commercial chemicals have
been screened
 ~2% determined to be carcinogen, teratogen or mutagen
 >1000 new synthetic chemicals added per year
 >99.5% of US commercial chemicals are NOT regulated
Chemical Hazards
What are toxic vs. hazardous chemicals?
• Toxic (poisonous) chemicals- substances that are fatal
to over 50% of test animals (LD50) at given
concentrations
• Hazardous chemicals- cause harm by
- Flammable or explosive (e.g., gasoline)
- Irritating or damaging the skin or lungs (e.g., strong
acids or alkalines such as oven cleaners)
- Interfering with or preventing oxygen uptake and
distribution (e.g., carbon monoxide, CO)
- Inducing allergic reactions
© Brooks/Cole Publishing Company / ITP
Hazardous chemicals
• Mutagens- cause random mutations, or changes in the
DNA
• Teratogens- cause birth defects
e.g., PCBs, steroid hormones, heavy metals, rubella,
mercury in water, fetal alcohol syndrome and crack
babies
• Carcinogens- cause cancer
- over 100 types of cancer (depending on cells involved)
- e.g., cigarette smoke.
- Hormone disrupters
© Brooks/Cole Publishing Company / ITP
Hormone Disrupters
Hormones -molecules that act
as messengers in the
endocrine system to regulate
reproduction, growth and
development.
Hormone disrupters (mimics
and blockers), attach to
receptors and disrupt/alter
development.
© Brooks/Cole Publishing Company / ITP
Hormone Disrupters
• 51 chemicals, many widely used, have been
shown to be hormone disrupters on wildlife,
laboratory animals and humans
- i.e. dioxins, certain PCBs, various chemicals in
plastics, some pesticides, lead and mercury
• 1997 study shows that sperm count of men in
U.S. and Europe has declined 50%.
© Brooks/Cole Publishing Company / ITP
Energy

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Energy- capacity to do work and
transfer heat
Measured in calories = amt of
heat required to raise the temp of
1.0g of water 1oC
Work is movement of matter
(pump gas through pipe, move
book)
Energy

Two types
 Kinetic
 Energy in motion
 Possessed by matter b/c of its
mass and speed (velocity)
 Potential
 Stored energy
 Potential to be changed into
kinetic energy
 Rock in hand, unlit match,
energy stored in bonds of
foodstuff, water behind dam
Energy
Electromagnetic radiation
Sun
High energy, short
wavelength
Low energy, long
wavelength
Nonionizing radiation
Ionizing radiation
Visible
CosmicGamma X rays
Far
Near
Near
Far Microwaves TV
rays
ultraviolet
ultraviolet
infrared infrared
rays
waves
waves waves
waves waves
10-14
10-12
10-8
10-7
10-6
10-5
10-3
10-2 10-1
•Electromagnetic radiation (EM)- energy traveling in waves as
a result of changing electric and magnetic fields
•Different forms with different wavelengths and energy content
•Electromagnetic Radiation Movie
Radio
waves
1
Energy
Electromagnetic radiation

Two types of EM radiation
 Ionizing EM radiation
 High energyknock e’s
from atoms and change
them to + ions
 e’s and ions disrupt living
cells-cancer
 Non-ionizing EM radiation
 Low energy Not highly
reactive or as dangerous.
 Visible light-- makes up
most of the spectrum of EM
radiation from the sun.
Energy
Heat
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Heat- total kinetic energy of all
moving atoms, ions or molecules
Temperature—average speed of
motion of the atoms, ions or
molecules in matter
Atoms move faster when heated
Heat energy flows hot  cold
Hot air/water less dense due to
energy so rises.
Energy
Quality

Energy quality- measure of energy
source’s ability to do useful work
 High quality
 Concentrated
 Can perform much useful work
 Chemical energy in coal and gas,
sunlight
 Low quality
 Dispersed
 Little ability to do work
 Heat in atmosphere or heat in
oceans
Energy Laws
1st Law of Thermodynamics

1st law of thermodynamics (Law of conservation of
energy)
 In all physical and chemical changes, energy is not
created or destroyed, but changes form
 Total energy of system remains constant
Energy Laws
2nd Law of Thermodynamics

2nd Law of Thermodynamics (Law of
disorder)
 When energy changed from one form
to another, useful energy is degraded
to lower quality, more dispersed, less
useful energy
 Light bulb---95% lost as waste heat
 Energy stored in food---most lost as
waste heat
 **We can never recycle or reuse
high-quality energy to perform useful
work
Solar
energy
Waste
heat
Mechanical
energy
(moving,
thinking,
living)
Chemical
energy
(food)
Chemical
energy
(photosynthesis)
Waste
heat
Waste
heat
Waste
heat
Nuclear Changes

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Matter can undergo physical, chemical OR nuclear
changes
Nuclear change--nucleus of certain isotopes
spontaneously change or are made to change into nuclei
of different isotopes
Matter  Energy
3 types of nuclear change
 Radioactive decay
 Nuclear fission
 Nuclear fusion
Nuclear Changes
Radioactive Decay

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Radioactive isotopes with unstable nuclei decay
Particles and/or damaging ionizing radiation, emitted
until nuclei stable and not radioactive
 Gamma rays
 Genetic damage to DNA
 Somatic damage to tissues
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
Table 3-1 Half-Lives of Selected Radioisotopes
Isotope
Radiation Half-Life
Emitted
Potassium-42
12.4 hours
Alpha, beta
Iodine-131
8 days
Beta, gamma
Cobalt-60
5.27 years
Beta, gamma
Hydrogen-3 (tritium)
12.5 years
Beta
Strontium-90
28 years
Beta
Carbon-14
5,370 years
Beta
Plutonium-239
24,000 years
Alpha, gamma
Uranium-235
710 million years
Alpha, gamma
Uranium-238
4.5 billion years
Alpha, gamma
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
Fission fragment
n
n
Energy
n
n
Uranium-235
nucleus
Energy
Unstable
nucleus
Fission fragment
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
235
92 U
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
Matter and Energy Laws
Environmental Problems


Law of conservation of matter and 1st and 2nd law of
thermodynamics together mean individual resource use
adds waste matter and heat to the environment
Different types of economic systems
 High-throughput, high waste economies
 Matter-recycling-and-reuse economy
 Low-throughput economy
Matter and Energy Laws
Environmental Problems
High-throughput Economy



Developed countries with ever increasing growth
Increased one-way flow of matter through systems and
out to planetary “sinks”--air, water, soil, and organisms
 Pollutants and wastes accumulate
 Output will exceed environment’s capacity to dilute
and degrade waste matter and absorb heat
UNSUSTAINABLE!
Matter and Energy Laws
Environmental Problems
Low-Throughput Economy

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Decrease matter and energy flow
Don’t waste matter and energy resources
Recycle and reuse
Stabilize population