Chapter 2Chapter 2

Science, Systems, Science, Systems, Matter, and EnergyMatter, and Energy

Feedback Loops: Feedback Loops: How Systems Respond to ChangeHow Systems Respond to Change

Outputs of matter, energy, or information fed Outputs of matter, energy, or information fed back into a system can cause the system to back into a system can cause the system to do do moremore or or lessless of what it was doing. of what it was doing. Positive feedback loop causes a system to Positive feedback loop causes a system to

change further in the same direction (e.g. change further in the same direction (e.g. erosion)erosion)

Negative (corrective) feedback loop causes a Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. system to change in the opposite direction (e.g. seeking shade from sun to reduce stress).seeking shade from sun to reduce stress).

Feedback Loops: Feedback Loops:

Negative feedback can take so long that a Negative feedback can take so long that a system reaches a threshold and changes.system reaches a threshold and changes. Prolonged delays may prevent a negative Prolonged delays may prevent a negative

feedback loop from occurring.feedback loop from occurring. Processes and feedbacks in a system can Processes and feedbacks in a system can

(synergistically) interact to amplify the results.(synergistically) interact to amplify the results. E.g. smoking exacerbates the effect of asbestos E.g. smoking exacerbates the effect of asbestos

exposure on lung cancer.exposure on lung cancer.

Organic Compounds: Carbon RulesOrganic Compounds: Carbon Rules

Organic compounds contain carbon atoms Organic compounds contain carbon atoms combined with one another and with various combined with one another and with various other atoms such as Hother atoms such as H++, N, N++, or Cl, or Cl--..

Contain at least two carbon atoms combined Contain at least two carbon atoms combined with each other and with atoms.with each other and with atoms. Methane (CHMethane (CH44) is the only exception.) is the only exception. All other compounds are All other compounds are inorganicinorganic..

Organic Compounds: Carbon RulesOrganic Compounds: Carbon Rules

HydrocarbonsHydrocarbons: compounds of carbon and : compounds of carbon and hydrogen atoms (e.g. methane (CHhydrogen atoms (e.g. methane (CH44)).)).

Chlorinated hydrocarbonsChlorinated hydrocarbons: compounds of : compounds of carbon, hydrogen, and chlorine atoms (e.g. carbon, hydrogen, and chlorine atoms (e.g. DDT (CDDT (C1414HH99CCl5l5)).)).

Simple carbohydratesSimple carbohydrates: certain types of : certain types of compounds of carbon, hydrogen, and oxygen compounds of carbon, hydrogen, and oxygen (e.g. glucose (C(e.g. glucose (C66HH1212OO66)).)).

States of MatterStates of Matter

The atoms, ions, and molecules that make up The atoms, ions, and molecules that make up matter are found in three physical states:matter are found in three physical states: solid, liquid, gaseous.solid, liquid, gaseous.

A fourth state, plasma, is a high energy A fourth state, plasma, is a high energy mixture of positively charged ions and mixture of positively charged ions and negatively charged electrons.negatively charged electrons. The sun and stars consist mostly of plasma.The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in Scientists have made artificial plasma (used in

TV screens, gas discharge lasers, florescent TV screens, gas discharge lasers, florescent light).light).

CHANGES IN MATTERCHANGES IN MATTER Matter can change from one physical form to Matter can change from one physical form to

another or change its chemical composition.another or change its chemical composition. When a physical or chemical change occurs, no When a physical or chemical change occurs, no

atoms are created or destroyed.atoms are created or destroyed.• Law of conservation of matter.Law of conservation of matter.

Physical change maintains original chemical Physical change maintains original chemical composition.composition.

Chemical change involves a chemical reaction Chemical change involves a chemical reaction which changes the arrangement of the elements which changes the arrangement of the elements or compounds involved.or compounds involved.• Chemical equations are used to represent the Chemical equations are used to represent the

reaction.reaction.

Chemical ChangeChemical Change

Energy is given off during the reaction as a product.Energy is given off during the reaction as a product.

Types of PollutantsTypes of Pollutants

Factors that determine the severity of a Factors that determine the severity of a pollutant’s effects: pollutant’s effects: chemical naturechemical nature, , concentrationconcentration, and , and persistencepersistence..

Pollutants are classified based on their Pollutants are classified based on their persistence:persistence: Degradable pollutantsDegradable pollutants Biodegradable pollutantsBiodegradable pollutants Slowly degradable pollutantsSlowly degradable pollutants Nondegradable pollutantsNondegradable pollutants

Nuclear Changes: Radioactive DecayNuclear Changes: Radioactive Decay

Natural radioactive decay: unstable isotopes Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of spontaneously emit fast moving chunks of matter (matter (alphaalpha oror beta particlesbeta particles), high-energy ), high-energy radiation (radiation (gamma raysgamma rays), or both at a fixed ), or both at a fixed rate.rate. Radiation is commonly used in energy production Radiation is commonly used in energy production

and medical applications.and medical applications. The rate of decay is expressed as a The rate of decay is expressed as a half-lifehalf-life (the (the

time needed for one-half of the nuclei to decay to time needed for one-half of the nuclei to decay to form a different isotope).form a different isotope).

Nuclear Changes: FissionNuclear Changes: Fission

Nuclear fission: Nuclear fission: nuclei of certain nuclei of certain isotopes with large isotopes with large mass numbers are mass numbers are split apart into split apart into lighter nuclei when lighter nuclei when struck by neutrons.struck by neutrons.

Figure 2-9Figure 2-9

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: FusionNuclear Changes: Fusion

Nuclear fusion: two isotopes of light elements Nuclear fusion: two isotopes of light elements are forced together at extremely high are forced together at extremely high temperatures until they fuse to form a heavier temperatures until they fuse to form a heavier nucleus.nucleus.

Figure 2-10Figure 2-10

ENERGYENERGY

Energy is the ability to do work and transfer Energy is the ability to do work and transfer heat.heat. Kinetic energy – energy in motionKinetic energy – energy in motion

• heat, electromagnetic radiationheat, electromagnetic radiation Potential energy – stored for possible usePotential energy – stored for possible use

• batteries, glucose moleculesbatteries, glucose molecules

Electromagnetic SpectrumElectromagnetic Spectrum

Many different forms of electromagnetic Many different forms of electromagnetic radiation exist, each having a different radiation exist, each having a different wavelength and energy content.wavelength and energy content.

Figure 2-11Figure 2-11

ENERGY LAWS: TWO RULES WE ENERGY LAWS: TWO RULES WE CANNOT BREAKCANNOT BREAK

The first law of thermodynamics: we cannot The first law of thermodynamics: we cannot create or destroy energy.create or destroy energy. We can change energy from one form to another.We can change energy from one form to another.

The second law of thermodynamics: energy The second law of thermodynamics: energy quality always decreases.quality always decreases. When energy changes from one form to another, When energy changes from one form to another,

it is always degraded to a more dispersed form.it is always degraded to a more dispersed form. Energy efficiency is a measure of how much Energy efficiency is a measure of how much

useful work is accomplished before it changes to useful work is accomplished before it changes to its next form.its next form.

Fig. 2-14, p. 45

Chemicalenergy(food)

Solarenergy

WasteHeat

WasteHeat

WasteHeat

WasteHeat

Mechanicalenergy

(moving,thinking,

living)

Chemical energy

(photosynthesis)

Sustainable Low-Throughput Sustainable Low-Throughput Economies: Learning from NatureEconomies: Learning from Nature

Matter-Recycling-and-Reuse Economies: Matter-Recycling-and-Reuse Economies: Working in CirclesWorking in Circles Mimics nature by recycling and reusing, thus Mimics nature by recycling and reusing, thus

reducing pollutants and waste.reducing pollutants and waste. It is not sustainable for growing populations.It is not sustainable for growing populations.