Chapter 3 Science, Systems, Matter, and Energy. Chapter Overview Questions What is science, and what do scientists do? What are major components and behaviors.

Chapter 3

Science, Systems, Matter, and Energy

Chapter Overview Questions• What is science, and what do scientists do?• What are major components and behaviors

of complex systems?• What are the basic forms of matter, and what

makes matter useful as a resource?• What types of changes can matter undergo

and what scientific law governs matter?

Chapter Overview Questions (cont’d)

• What are the major forms of energy, and what makes energy useful as a resource?

• What are two scientific laws governing changes of energy from one form to another?

• How are the scientific laws governing changes of matter and energy from one form to another related to resource use, environmental degradation and sustainability?

Core Case Study: Environmental Lesson from Easter

Island• Thriving society

– 15,000 people by 1400.• Used resources faster

than could be renewed– By 1600 only a few

trees remained.• Civilization collapsed

– By 1722 only several hundred people left.

Figure 2-1

Video: Easter Island

https://www.youtube.com/watch?v=v40kCIpgEWw

THE NATURE OF SCIENCE

• What do scientists do?– Collect data.– Form hypotheses.– Develop theories,

models and laws about how nature works.

Figure 2-2

Fig. 2-2, p. 29

Well-tested andaccepted patterns

in data becomescientific laws

Interpret data

Ask a question

Do experimentsand collect data

Formulate hypothesisto explain data

Do more experimentsto test hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Ask a question

Do experimentsand collect data

Formulate hypothesisto explain data

Do more experimentsto test hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Interpret data

Well-tested andaccepted patternsIn data becomescientific laws

Fig. 2-3, p. 30

Stepped Art

Scientific Theories and Laws: The Most Important Results of

Science• Scientific Theory– Widely tested and

accepted hypothesis.

• Scientific Law– What we find

happening over and over again in nature.

Figure 2-3

Fig. 2-3, p. 30

Research results

Scientific paper

Peer review byexperts in field

Paperrejected

Paper accepted

Paper published inscientific journal

Research evaluatedby scientific community

Testing Hypotheses• Scientists test hypotheses using controlled

experiments and constructing mathematical models.– Variables or factors influence natural

processes– Single-variable experiments involve a control

and an experimental group.– Most environmental phenomena are

multivariable and are hard to control in an experiment.• Models are used to analyze interactions of

variables.

Scientific Reasoning and Creativity

• Inductive reasoning– Involves using specific observations and

measurements to arrive at a general conclusion or hypothesis.

– Bottom-up reasoning going from specific to general.

• Deductive reasoning– Uses logic to arrive at a specific conclusion.– Top-down approach that goes from general to

specific.

Frontier Science, Sound Science, and Junk Science

• Frontier science has not been widely tested (starting point of peer-review).

• Sound science consists of data, theories and laws that are widely accepted by experts.

• Junk science is presented as sound science without going through the rigors of peer-review.

Limitations of Environmental Science

• Inadequate data and scientific understanding can limit and make some results controversial.– Scientific testing is based on disproving rather

than proving a hypothesis.• Based on statistical probabilities.

MODELS AND BEHAVIOR OF SYSTEMS

• Usefulness of models– Complex systems are predicted by developing a

model of its inputs, throughputs (flows), and outputs of matter, energy and information.

– Models are simplifications of “real-life”.– Models can be used to predict if-then scenarios.

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.

TYPES AND STRUCTURE OF MATTER

• Elements and Compounds– Matter exists in chemical forms as elements and

compounds.• Elements (represented on the periodic table) are the

distinctive building blocks of matter.• Compounds: two or more different elements held

together in fixed proportions by chemical bonds.

Atoms

Figure 2-4

Ions

• An ion is an atom or group of atoms with one or more net positive or negative electrical charges.

• The number of positive or negative charges on an ion is shown as a superscript after the symbol for an atom or group of atoms – Hydrogen ions (H+), Hydroxide ions (OH-)– Sodium ions (Na+), Chloride ions (Cl-)

• The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution.

Figure 2-5

Compounds and Chemical Formulas

• Chemical formulas are shorthand ways to show the atoms and ions in a chemical compound. – Combining Hydrogen ions (H+) and Hydroxide

ions (OH-) makes the compound H2O (dihydrogen oxide, a.k.a. water).

– Combining Sodium ions (Na+) and Chloride ions (Cl-) makes the compound NaCl (sodium chloride a.k.a. salt).

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)).

Cells: The Fundamental Units of Life

• Cells are the basic structural and functional units of all forms of life.– Prokaryotic cells

(bacteria) lack a distinct nucleus.

– Eukaryotic cells (plants and animals) have a distinct nucleus.

Figure 2-6

Fig. 2-6a, p. 37

(a) Prokaryotic Cell

Protein constructionand energy conversionoccur without specializedinternal structures

Cell membrane(transport ofraw materials and finished products)

DNA(information storage, no nucleus)

Fig. 2-6b, p. 37

Protein construction

(b) Eukaryotic Cell

Cell membrane(transport of rawmaterials andfinished products)Packaging

Energy conversion

Nucleus (informationstorage)

Macromolecules, DNA, Genes and Chromosomes

• Large, complex organic molecules (macromolecules) make up the basic molecular units found in living organisms.– Complex carbohydrates– Proteins– Nucleic acids– Lipids

Figure 2-7

Fig. 2-7, p. 38

The genes in each cell are coded by sequences of nucleotides in their DNA molecules.

A human body contains trillions of cells, each with an identical set of genes.

There is a nucleus inside each human cell (except red blood cells).

Each cell nucleus has an identical set of chromosomes, which are found in pairs.

A specific pair of chromosomes contains one chromosome from each parent.

Each chromosome contains a long DNA molecule in the form of a coiled double helix.

Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life.

Fig. 2-7, p. 38

A human body contains trillionsof cells, each with an identicalset of genes.

There is a nucleus inside eachhuman cell (except red blood cells).

Each cell nucleus has an identicalset of chromosomes, which arefound in pairs.

A specific pair of chromosomescontains one chromosome fromeach parent.

Each chromosome contains a longDNA molecule in the form of a coileddouble helix.

Genes are segments of DNA onchromosomes that contain instructionsto make proteins—the building blocksof life.

The genes in each cell are codedby sequences of nucleotides intheir DNA molecules.

Stepped Art

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).

Matter Quality• Matter can be classified

as having high or low quality depending on how useful it is to us as a resource.– High quality matter is

concentrated and easily extracted.

– low quality matter is more widely dispersed and more difficult to extract.

Figure 2-8

Fig. 2-8, p. 39

High Quality Low Quality

Salt

Solid Gas

Coal Coal-fired power plant emissions

GasolineAutomobile emissions

Solution of salt in water

Aluminum oreAluminum can

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.

p. 39

Reactant(s) Product(s)

carbon + oxygen carbon dioxide + energy

C + O2 CO2 energy+

energy+

black solid colorless gas colorless gas

+

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

Fig. 2-9, p. 41

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Neutron

FissionFragment

FissionFragment

Energy

EnergyEnergy

Energy

n

n

n

n

n

n

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235 Fig. 2-6, p. 28

Neutron

Uranium-235

Energy

Fissionfragment

Fissionfragment

n

n

n

n

n

n

Energy

Energy

Energy

Stepped Art

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

Fig. 2-10, p. 42

Neutron

+

Hydrogen-2(deuterium nucleus)

Hydrogen-3(tritium nucleus)

+

Proton Neutron

100million °C

Energy

+

Helium-4 nucleus

ProductsReaction

ConditionsFuel

+

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

Fig. 2-11, p. 43

Sun

Nonionizing radiationIonizing radiation

High energy, shortWavelength

Wavelength in meters(not to scale)

Low energy, longWavelength

Cosmicrays

GammaRays

X raysFar

infrared waves

Nearultra-violetwaves

VisibleWaves

Nearinfraredwaves

Farultra-violetwaves

Micro-waves

TVwaves

RadioWaves

Electromagnetic Spectrum

• Organisms vary in their ability to sense different parts of the spectrum.

Figure 2-12

Fig. 2-12, p. 43

En

erg

y em

itte

d f

rom

su

n (

kcal

/cm

2 /m

in)

Wavelength (micrometers)

Ult

ravi

ole

t

Visible

Infrared

Fig. 2-13, p. 44

Low-temperature heat (100°C or less) for space heating

Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing

steam, electricity, and hot water

Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors)

Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity

Dispersed geothermal energyLow-temperature heat (100°C or lower)

Normal sunlightModerate-velocity windHigh-velocity water flowConcentrated geothermal energyModerate-temperature heat

(100–1,000°C)Wood and crop wastes

High-temperature heat (1,000–2,500°C)Hydrogen gasNatural gasGasolineCoalFood

ElectricityVery high temperature heat (greater than 2,500°C)Nuclear fission (uranium)Nuclear fusion (deuterium)Concentrated sunlightHigh-velocity wind

Source of Energy RelativeEnergy Quality

(usefulness)

Energy Tasks

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.

Fig. 2-14, p. 45

Chemicalenergy(food)

Solarenergy

WasteHeat

WasteHeat

WasteHeat

WasteHeat

Mechanicalenergy

(moving,thinking,

living)

Chemical energy

(photosynthesis)

SUSTAINABILITY AND MATTER AND ENERGY LAWS• Unsustainable High-Throughput

Economies: Working in Straight Lines– Converts resources to goods in a manner that

promotes waste and pollution.

Figure 2-15

Fig. 2-15, p. 46

High-quality energy

Matter

Unsustainablehigh-waste

economy

SystemThroughputs

Inputs(from environment)

Outputs(into environment)

Low-quality energy (heat)

Waste and pollution

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.

Fig. 2-16, p. 47

Recycleand

reuse

Low-quality Energy(heat)

Waste and

pollution

Pollutioncontrol

Sustainable low-waste economy

Waste and

pollution

Matter Feedback

Energy Feedback

Inputs (from environment)

Energyconservation

Matter

Energy

SystemThroughputs

Outputs(into environment)