Science, Matter, Energy, and Systems
Chapter 2 – Part 1
Scientific Process
Core Case Study: Carrying Out a Controlled
Scientific Experiment
 F. Herbert Bormann, Gene Likens, et al.: Hubbard
Brook Experimental Forest in NH (U.S.)
 Compared the loss of water and nutrients from an
uncut forest (control site) with one that had been
stripped (experimental site)
The Effects of Deforestation on the Loss of
Water and Soil Nutrients
 Built v-shaped dams
across the creeks at the
bottom of forested
valleys
 Measured amounts of
water and dissolved
plant nutrients
The Effects of Deforestation on the Loss of
Water and Soil Nutrients
 Investigators cut down
all trees and shrubs in
one valley
 Sprayed area with
herbicides to prevent
regrowth
The Effects of Deforestation on the Loss of
Water and Soil Nutrients
 Amount of water
flowing out of the
deforested valley
increased by 30-40%
• Eroded soil
• Removed 6x more
nutrients from soil
 Conclusions????
Scientists Use Reasoning, Imagination, and Creativity
to Learn How Nature Works
 Important scientific tools
• Inductive reasoning – involves using specific
observations and measurements
• Specific  General
• Deductive reasoning – involves using logic to arrive
at a specific conclusion based on a generalization or
premise
• General  Specific
Inductive or Deductive?
 All birds have feathers.  Eagles are birds.  Eagles
have feathers.
 A meatball falls to the ground when dropped from a
height of 10 feet.  An olive falls to the ground
when dropped from a height of 2 feet.  All objects
fall to the Earth’s surface when dropped.
Nature of Science
 An organized way of
using evidence to learn
about the natural world
•
•
•
•
•
•
•
Observations
Hypothesis
Experiment
Results
Conclusion
Repeating
Peer Review
Nature of Science

Hypothesis
•

Proposed scientific explanation for a set
of observations
A good hypothesis must:
1. Be testable.
2. Be a statement, not a question.
3. Predict cause and effect.
If…
then…
Nature of Science

Null Hypothesis:
•
•
•
States that the variable will have no
effect on the outcome of the
experiment
Example: Light intensity has no
effect on plant growth.
Allows conclusions to be drawn that
“reject” or “fail to reject” the null
hypothesis
If…
then…
Variable
Change
Able to
 Every experiment measures two
• Independent variable -- the variable that the
experimenter controls.
• answers the question "What do I change/control?"
• Dependent variable -- the variable the experimenter
measures (results).
• answers the question "What do I observe/measure?"
Scenario
 A group of students is assigned a populations
project in their APES class. They decide to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Independent Variable – What do I control ?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Dependent Variable – What do I measure?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Controlled Experiment
 Experimental group - group that receives treatment
in a controlled experiment.
• Contains Independent Variable
 Control group - group that does not receive
treatment in a controlled experiment.
• Does not contain Independent Variable
Experimental Group– Which group has the
IV?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Control – Which group doesn’t have the IV?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Variable
Change
Able to
 Levels – measure of your independent variable
• Example:
• Number of seeds in a pot
• Number of fish in a fish bowl
• Number of times that an action is repeated
Levels – how is the IV measured?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Controlled Experiment
 Constant
• What remains constant between experimental groups
 Trials
• Number of times you repeat an experiment
• More tries = more reliable results
 Sample size
• The number of objects or events studied
Constants – What do I keep the same?
 A group of students is assigned a populations
project in their APES class. They decided to
determine the effect of sunlight on radish plant
height. They set up 3 clay pots, each one containing
12 radish plants, 100g of potting soil, and given 25
mL of water daily. The pots are all 4 inches in
diameter. One pot is placed in 24 hours darkness,
one in 12 hours sunlight/12 hours darkness, and the
last in 24 hours sunlight. After 5 days, they measure
the height of all the plants in each pot.
Not all experiments are created equal…
 Frontier science –
preliminary testing
 Reliable science – well
supported and studied
experiments
• High probability of
being true
 Unreliable –
unsupported via peer
review
 Critical Thinking
Questions:
• Was the experiment
controlled?
• Have the data been verified?
• Have the results been
reproduced by other
scientists?
• Are the investigators
unbiased?
• Have the conclusions been
verified by impartial peer
review?
Scientific Theories and Laws
 Theory
• Verified, credible and
widely accepted
hypothesis
• Make future predictions
 Law
• Mathematical
description of what a
theory explains
 Paradigm Shift
• Majority of scientists in
a field accept a new
framework for theories
and laws
Your Turn!
 Case of the Ivory Billed Woodpecker
 http://www.pbs.org/wgbh/nova/nature/ivory-billedwoodpecker.html
The Case of the Ivory Billed Woodpecker
 Case of the Ivory Billed Woodpecker
 http://www.pbs.org/wgbh/nova/nature/ivory-billedwoodpecker.html
The Case of the Ivory Billed Woodpecker
Wisconsin Fast Plants Laboratory Project
1. Make a list of questions you have about plants.
•
Be creative!
2. Suggested IV:
•
•
•
•
•
Fertilizer
Crowding
Acid (vinegar)
Soil
Glucose
Your Turn: Wisconsin Fast Plant Project!
1. On your paper include the following information:
1.
2.
3.
4.
Question
Hypothesis
Null Hypothesis
Experimental Design
1.
2.
3.
4.
5.
Independent and Dependent Variable
Control and Experimental Groups
Levels
Constants
Sample Size
5. Detailed Procedure
Peer Review
 Is the hypothesis testable, a statement, and does it
predict a cause and effect relationship?
 Will the data be quantitative rather than qualitative?
 Are there any unaccounted for variables? If so, what
are they?
 Is the procedure logical?
 Any remaining questions or comments?
Science, Matter, Energy, and Systems
Chapter 2 – Part 2
Chemical Bonding
Matter
Any substance that:
 Occupies space
 Has mass
 Is made of atoms
Some Forms of Matter Are More
Useful than Others
 Matter quality –
measure of how useful
a form of matter is to
humans as a resource
• Based on availability and
concentration
Some Forms of Matter Are More
Useful than Others
 High-quality matter
• highly concentrated
• Near the Earth’s surface
• Great potential as a
resource
 Low-quality matter
• Not highly concentrated
• Located deep
underground or ocean
• Little potential for use
We Cannot Create or Destroy Matter
 Matter consumption
• Matter is converted
from one form to
another
 Law of conservation of
matter – matter cannot
be created nor
destroyed
Everything we think we have thrown away remains here with us
in some form…
Matter Consists of Elements and Compounds
 Elements
• Unique properties
• Cannot be broken down chemically into other
substances
• SPONCH
 Compounds
• Two or more different elements bonded together in
fixed proportions
Organic Compounds Are the
Chemicals of Life
 Inorganic compounds
 Organic compounds
• Macromolecules: complex organic molecules
•
•
•
•
Carbohydrates
Proteins
Nucleic acids
Lipids
Atomic Composition
 No unique substances
in living things, just
different amounts
 “Same ingredients,
different recipes.”
Example: Carbon
• Atomic Number = 6
•6 Protons
•6 Electrons
•Atomic Mass = 12
•12 – 6 = 6
•6 Neutrons
Your Turn!
 Atomic Mass #...
ELECTRONEGATIVITY
 The tendency of an atom to attract electrons to
itself when it is bonded to another atom
Increase
Increase
BONDING OPTIONS
COVALENT BOND
 By sharing electrons
(small difference in EN)
IONIC BOND
 By transferring electrons (producing ions)
(big difference in EN)
Chemical Bonding
 Atoms combine according to certain rules
• Rules determined by the number of electrons found
in the outermost energy level
• First energy level = 2 electrons
• Second energy level = 8 electrons
• Third energy level = 8 electrons
Chemical Bonding
Covalent Bonds
 Sharing of electrons
• Electrons travel in the
orbitals of both atoms
 Each atom fills out the
outermost energy level
Water: A Covalent Bond
Ionic Bonds
 Transfer of electrons
 Ex. NaCl
• Sodium has one
electron in outer shell
Na +
• Chlorine has seven
electrons in its outer
shell Cl –
Ionic Bond
 Ion = charged particle
• Anion = negatively charged
• Cation = positively charged
 Strong attraction between oppositely charged ions
forms the ionic bond
Ionic Bond
Trick to Remember!
 If an atom GAINS electrons, its overall
charge becomes more negative.
 If it LOSES electrons, its charge
becomes more positive
Your Turn!
 Bonding Practice
 Covalent: Carbon and Chlorine
 Ionic: Sodium and Chlorine
Science, Matter, Energy, and Systems
Chapter 2 – Part 3
Water
Why is it important?
 Covers ¾ of Earth’s surface!
• Most abundant compound in most living
things
 Exceptional substance with many
extraordinary qualities!
Unusual Properties
 Determine characteristics of:
Water’s Structure…Simple?
 Hydrogen
• 1 electron…needs 2
 Oxygen
• 6 electrons (outer
shell)…needs 8
 Covalent Bonding
Polar Molecule
 Charges are unevenly
distributed
• Partial positive
• Partial negative
 Electronegativites of atoms
differ
Electronegativity
Electronegativity
Hydrogen Bonds
 Attraction between two
different molecules
 “weak” bond
 Not “real” bond b/c no
sharing or transferring of
electrons
• Ex: water, proteins, & DNA
How many hydrogen bonds can each
water molecule form?
As one hydrogen bond is broken
another one forms
 Each bond lasts
trillionths of a second
 Substantial
percentage bonded to
neighbor
Cohesion
 Attraction between
molecules of the same
substance
 Causes molecules on the
surface of water to be drawn
inward
• Why water forms beads on
smooth surfaces
• Why insects can walk on
water
Surface Tension
 Result of cohesion
 How it “stretches or resists
breaking”
 Water molecules form
weak elastic membrane
• Water to water
• Water to air
Adhesion
 Attraction between molecules
of different substances
• Meniscus
Water to Water
Water to Glass
Capillary Action
 Forces that draw water out of
the roots of a plant and up into
its stems and leaves
 Holds column of water
together as it rises
 Cohesion and adhesion
Density
 Less dense as a solid
 Hydrogen bonds stay
connected
• less energy in system so
bonds don’t break
 More space occurs between
water molecules
Solutions
 All components are evenly
distributed throughout
• Solute – substance that is
dissolved
• Solvent – the substance in
which the solute dissolves
 Due to water’s polarity
• Can dissolve ionic compounds
and other polar molecules
Solubility
 Water surrounds the
charged ends and separates
the molecules
Suspensions
 Mixtures of water and
nondissolved material
• Materials don’t dissolve
but separate into pieces so
small that they do not
settle out
 Example
• Blood
Your Turn!
 Water Property Lab
Science, Matter, Energy, and Systems
Chapter 2 – Part 4
Isotopes and Nuclear Reactions
Isotopes
 Number of neutrons can vary from one
atom of an element to another
• Changes atomic mass, not atomic number
 Atomic number NEVER changes
Isotopes
1
1
1
2
1
3
H = hydrogen
H = deuterium
H = tritium
Isotopes
 Isotopes have SAME number of protons but
DIFFERENT numbers of neutrons
• Heavier
• Behave identical in chemical reactions
 Same # electrons = same chemical properties
Radioactive Isotopes
 Diagnose and treat
diseases
• Cardiovascular disease
• Cancer radiation
 Sterilize foods
• Kill bacteria
• Preserve food
 Measure the ages of
certain rocks
• Fossils
Matter Undergoes Physical, Chemical, and
Nuclear Changes
 Nuclear change –
changes in the nuclei
of atoms
• Nuclear fission – nucleus
splits and releases
neutrons plus energy
Matter Undergoes Physical, Chemical, and
Nuclear Changes
 Nuclear change –
changes in the nuclei
of atoms
• Nuclear fission – nucleus
splits and releases
neutrons plus energy
• Nuclear fusion – two
nuclei fuse together and
release energy
Nuclear Power 6:51
Light-Water-Moderated and -Cooled Nuclear
Power Plant with Water Reactor
After 3 or 4 Years in a Reactor, Spent Fuel Rods
Are Removed and Stored in Water
Science, Matter, Energy, and Systems
Chapter 2 – Part 5
pH
What do vinegar, lemons, and orange juice have
in common?
Characteristics of Acids
 Taste Sour
 React with metals
 Often produce
hydrogen gas
 Can burn your skin
What do milk, Comet, and Tums have in
common?
Characteristics of Bases
 Taste Bitter
 Feel Slippery
 Neutralize Acids
• Antacids
 Dissolve grease
But, what
exactly are
acids and
bases?
Acid
 Substance that
ionizes in water
to give
hydrogen ions
(H+)
Examples of Acids





HCl
H2SO4
HNO3
HF
Juices
Base
 Substance that
ionizes in water to
give hydroxide
ions
(OH-)
Examples of Bases




NaOH
Ca(OH)2
KOH
Soap, Ammonia,
Baking Soda
The pH Scale
 Measurement system that indicates the
concentration of H+ ions in solution.
• The pH scale ranges from 0 to 14.
The pH Scale
 pH = “power of hydrogen”
• Each step increases by a power of ten
pH Scale
pH Calculations
 Remember: For every one-increment change in pH,
the ions change by a factor of 10.
 Example: What is the difference in H+
concentration between pH 6 and pH 4?
• pH 6 – pH 4 = pH 2
• H+ is 100 times more concentrated in the pH 4
solution
pH Calculations
 Remember: Concentration of H+ and OH- always
equals 10-14 M or pH 14
 Example: [H+] = 10-6 M
• pH is 6: weak acid
• [OH-] = 10-8 M
pH and Water
 Why does water have a pH of 7?
• Hydronium ions = hydroxide ions
• (H+) = (OH-)
H20
+
H + OH
Interesting fact…
Water can
act as an acid
or a base!!!
Interesting fact…
 Amphoteric substance that can
act as either an
acid or a base.
Your Turn!
 Review of pH Calculations
pH Scale
Your Turn…pH of natural substances
 Substances:
•
•
•
•
Soil
Freshwater
Saltwater
Rainwater
 Tools:
• Soil – capsules
• Water (use 2 of the following) - pH meter, litmus
paper, or microkit
Your Turn…pH of natural substances
Capsules
Soil
Freshwater
Saltwater
Rainwater
pH Meter
Litmus
Paper
Microkit
Buffers
 Weak acids or bases
that can react with
strong acids or bases to
prevent sharp, sudden
changes in pH.
Buffers are
working while
you exercise!
Ocean pH
 Surface water pH ranges from 8.0 to 8.3
• Average 8.1
 Ocean water combines with CO2
 Forms weak Carbonic Acid
H20 + CO2
H2CO3
H+ + HCO3-
Ocean pH
 Average pH 8.1
• BASIC?
 Carbonic Acid?
Why is the ocean pH slightly basic when
CO2 (an acid) is added?
Carbonate Buffering
 Keeps ocean pH about same (8.1)
 pH too high, carbonic acid releases H+
H2CO3
H+ + HCO3-
 pH too low, bicarbonate combines with H+
HCO3- + H+
H2CO3
Carbonate Buffering
 Marine organisms die and sink into deep ocean
• Calcium carbonate in shell neutralizes acid through
buffering
CaCO3
HCO3- + H+
CO3- + H+
H2CO3
Carbonate Buffering
 Dead mollusks are the antacids of the sea!
Carbonate buffering
Recent Decrease in Ocean Acidity
 Excess carbon dioxide in atmosphere
• 33% CO2 released by burning fossil fuels ends up in
ocean
 Overwhelming oceans natural ability to buffer itself
• pH has decreased 0.1 since preindustrial times
Recent Decrease in Ocean Acidity
 More difficult for certain marine creatures to build
hard parts out of calcium carbonate
• Plankton
• Corals
 Alter food chain of ocean!
Science, Matter, Energy, and Systems
Chapter 2 – Part 6
Thermodynamics
Energy Comes in Many Forms
 Kinetic energy energy of motion
• Mass and velocity!
• Electromagnetic
radiation of waves
• Short = greater energy
Kinetic energy
 Atoms and molecules in any gas, liquid,
or solid are always in motion
• Vibrate around average position
 Kinetic Energy = ½ (mass)(velocity)2
Temperature
 Measure of the average
kinetic energy of the
atoms and molecules in
the substance
 Measured in degrees
• Celsius
• Fahrenheit
• Kelvin
Heat
 Measure of total kinetic
energy of the atoms
and molecules in a
substance
 Measured in calories
Calorie
 Amount of heat needed to raise the temperature of 1g
of water by 1oC
 1 food Calorie (1 kilocalorie) = 1000 calories
What’s the difference?
 Which has greater average
Kinetic Energy?
• Higher Temperature?
 Which has greater total
Kinetic Energy?
• More Heat?
Energy Comes in Many Forms
 Potential energy energy of position
• Stored energy; can be
changed into kinetic
energy
• Examples: rock held in
hand, unlit match,
gasoline
Some Types of Energy Are More
Useful Than Others
 Energy quality measure of an energy
source’s capacity to do
useful work
 High-quality energy –
concentrated energy that
has a high capacity to do
useful work
• High-temperature heat
• Concentrated sunlight
• High velocity wind
Some Types of Energy Are More
Useful Than Others
 Energy quality measure of an energy
source’s capacity to do
useful work
 Low-quality energy –
energy that is dispersed
and has little capacity
to do useful work
• Low temperatures
Energy Changes Are Governed by Two
Scientific Laws
 First Law of Thermodynamics
• Energy input always equals energy output
 Second Law of Thermodynamics
• Energy always goes from a more useful to a less
useful form when it changes from one form to
another
• Decreased energy efficiency
Life application
 94% of the money you
spend for gasoline is
not used to transport
you anywhere!
The Second Law of Thermodynamics
in Living Systems
Your Turn!
 Potential vs. Kinetic worksheet
Science, Matter, Energy, and Systems
Chapter 2 – Part 7
Systems
Systems Have Inputs, Flows,
and Outputs
 System – set of
components that
function and interact in
some regular way
• Inputs from the
environment
• Flows, throughputs
• Outputs
Systems Respond to Change through
Feedback Loops
 Positive feedback loop
- causes a system to
change in the same
direction
Systems Respond to Change through
Feedback Loops
 Negative feedback
loop – causes a system
to change in the
opposite direction from
which it is moving
• Opposing process
 Can promote
sustainability!
• Aluminum mining 
can  recycling
Video Clip – Planet Earth Forests
 Cicada Life Cycle
 21:00-26:00
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
• Example: Planting trees
 Tipping point,
threshold level
• Causes a shift in the
behavior of a system
System Effects Can Be Amplified
through Synergy
 Synergistic interaction – two or more processes
interact so that the combine effect is greater than
the sum of their separate effects
• Helpful
• E.g., campaign vs. individual persuasion
• Harmful
• E.g., Smoking and inhaling asbestos particles