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Science. Matter. Energy. Systems.

Chapter 2

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Important Definitions to Review

Science – knowledge of how the world works

Technology – creation of new processes intended to improve the quality of life

Law – certain phenomena always act in a predictable manner

Theory – rational explanation for numerous observations of a certain phenomena – global warming due to greenhouse effect

Accuracy – measurement agrees with the accepted correct value

Precision – measure of reproducibility

Inductive reasoning- using observations and facts to arrive at generalizations

Deductive reasoning - using logic to arrive at a specific conclusion

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Scientific methodidentify question/problemHYPOTHESIS – proposed to explain observed patternsComplete experiment and collect dataAnalysis and conclusions (results tentative, reliable or unreliable)Experiments subject to peer reviewidentify biasesIdentify limitations

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Systemssystem: set of components that interact in some regular wayOpen system: systems the exchange both energy and matter across their boundaries

most environmental systems open Inputs - matter, energy, information Throughput - flow of input Output - matter, energy, information flowing

outClosed system: exchange energy but not matter across their boundaries

ex. water cyclefeedback loop: Change in one part of a system influences another part of the system

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Positive feedback loopcauses a system to change further in the same direction. (farther from normal) Exponential growth

of population – more individuals lead to increased number of births

Precipitation causes erosion. Erosion causes plants to die. More precipitation causes more erosion and more vegetation death.

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Negative feedback loop

system to change in the opposite direction from which it is moving (closer to normal)

Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating

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Implications for the environment – High waste society

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Implications for the environment – Low waste society

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Complex systemsTime lags – change in a system leads to other changes after a delay

lung cancer

Resistance to change – built in resistance –

political, economic

Synergy-when two or more processes interact so that the combined effect is greater

Can be beneficial or harmful

Chaos – unpredictable behavior in a system

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Matter and Energy Resources

Nature’s Building Blocksanything that has mass and takes up space

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Forms of matter

elements – single type of atoms 110 elements

92 natural, 18 synthesized table 2.1 (important elements)compounds - 2 or more elements, held together by chemical bonds table 2.3 (important compounds)

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Atomic Theory Definitions

atoms - smallest units of matter- protons (+), neutrons (0), electrons (-) protons/neutrons in nucleus of atom atomic # = # of protons isotope: same atomic number but different

mass number (different form of the same element) Carbon-14; Uranium-235

ion - electrically charged atoms Table 2.2 (important ions)

molecules - combinations of atoms of the same or different elements

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Some Important elementscomposition by weight – only 8

elements make up 98.5% of the Earth’s crust

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Organic Compounds

with 2 or more atoms of carbon hydrocarbons: carbon and hydrogen atoms

methane CH4 (only exception to 2 C rule) Octane C8H18

chlorinated hydrocarbons: carbon, hydrogen and chlorine DDT C14H9Cl5

Simple carbohydrates: carbon, hydrogen and oxygen glucose C6H12O6

Also includes Polymers. complex carbohydrates (made of simple sugars), nucleic acids (made of nucleotides), proteins (made of amino acids) and lipids

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Inorganic compounds

no carbon, not originating from a living source

Earth’s crust – minerals, waterwater, nitrous oxide, nitric oxide, sodium chloride, ammonia

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Matter quality

Measure of how useful a matter is for humans based on availability and concentration

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Energycapacity to do work and transfer heat Kinetic Energy -energy in action

electromagnetic radiation (energy in waves resulting from electrical/magnetic fields), heat (energy in moving atoms)

Potential energy - stored energy that is potentially available; may be changed to kinetic

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Electromagnetic radiationdifferent wave lengths Shorter wavelength= high energy

disrupts cells with long term exposure

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Energy sources

99% of the energy that supports earth comes from the sun without it earth’s temperature -240 C or -

400 F allows for wind, hydro and biomass sources

of renewable energy

1% - commercial sources. Burning oil, coal and natural gas.

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Energy quality

Measure of how useful an energy source is in terms of concentration and ability to perform useful work

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Energy Changesenergy changes governed by 2 scientific laws law of conservation of energy (first law of

thermodynamics) no energy is created or destroyed as it

changes from one form to another energy input = energy output can lose energy quality (converted to a

less useful form) second law of thermodynamics

as energy changes form we end up with a lower quality or less usable energy source (heat)

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Nuclear Changesnuclei of certain isotopes spontaneously change (radioisotopes) or made to change into one or more different isotopes

Occurs with one of the following particles:Alpha particles – fast moving (2 protons+2 neutrons)

Beta particles – high speed electrons

Gamma particles - high energy electromagnetic radiation

radioactive decay, nuclear fission, nuclear fusion

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Use….radioisotopesEstimate age of rocks and fossilsTracers in pollution detection and medicineGenetic control of insects

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Half – Life (radioactive decay)

time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation.

ranges from fraction of a second to millions of years

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Nuclear Fissioncertain

isotopes (uranium-235) split apart into lighter nuclei + neutrons when struck by neutronschain reaction releases energyReleases an enormous amount of energy very quickly

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Nuclear fusion

two isotopes (hydrogen) forced together at extremely high temperatures (100 million C)

Fuse to form a heavy nucleus and release a tremendous amount of energy