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G. Tyler Miller’s Living in the Environment 13th Edition Chapter 3
Science, Systems, Matter, and Energy
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Key Concepts Science as a process for understanding
Components and regulation of systems Matter: forms, quality, and how it changes; laws of matter Energy: forms, quality, and how it changes; laws of energy Nuclear changes and radioactivity
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Science, and Critical Thinking
Scientific data Facts Scientific hypothesis Explanation of what is observed in nature Scientific (natural) laws Scientific theories Consensus science Data, theories, and laws that widely accepted by the scientific community Frontier science Preliminary results Ask a question Do experiments and collect data Formulate hypothesis to explain data Do more Experiments to test hypothesis Revise hypothesis if necessary Well-tested and accepted hypotheses become scientific theories Interpret data accepted patterns In data become scientific laws Fig. 3-2 p. 41
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Formulate a Hypothesis
Scientific Method Make Observations Formulate a Hypothesis Test Hypothesis Collect Data Interpret Data Draw Conclusions
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Controlled Experiment (Single Variable Analysis)
Experimental Group Variables change in a known way Independent variable Dependent Variable Control Group (Controls) Variables are not changed Controls Constants Data Quantitative - numbers Qualitative - descriptions
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Types of Reasoning Inductive reasoning Deductive reasoning
Using specific observations and measurements to arrive at a general conclusion bottom-up reasoning Deductive reasoning Reasoning that goes from the general to the specific top-down reasoning
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Models and Behavior of Systems
System – a set of components that function in a regular and predictable manner can be isolated for observation and study
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Models and Behavior of Systems
Inputs matter, energy, information Flows throughputs of matter, energy, or information at certain rates Stores storage areas for matter, energy or information Outputs Form of matter, energy, or information that flow out of the system and into sinks in the environment
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Models Approximate representations or simulations of real systems to
find out how systems work evaluate which ideas or hypotheses work Mental models – what do you think Mathematical models – one or more equations To describe the behavior of a system Make predictions about the behavior of a system Conceptual models Qualitative Numerical models Computer simulations
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System Regulation Feedback loop – when output of matter, energy, or information is fed back into the system as an input that changes the system. Positive Feedback – causes change in the same direction Negative Feedback – one change leads to a lessoning of that change. Coupled loops
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System Regulation Homeostasis – maintenance of a favorable internal condition of a system despite external changes. Time Delay – delay in expected effect Synergy – the combined effect of two or more processes is greater than the sum of the separate effects Fig. 3-3 p. 46
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Matter: Forms, Structure, and Quality
Elements Building blocks of matter Compounds Two or more different elements held together by chemical bonds Mixtures Combinations of various elements, compounds, or both Molecules Two or more atoms of the same or different elements held together by chemical bonds Example: O2 Matter – anything that has mass and takes up space. Two chemical forms – elements and compounds
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Atom – the smallest unit of matter that is unique to a particular element.
Subatomic Particles Protons Positively charges Neutrons uncharged Electrons Negatively charged
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Atomic Characteristics
Atomic Number Number of protons in the nucleus Atomic Mass Number of protons and neutrons Ions Atoms that have lost or gained electrons Isotopes Forms of a element having the same atomic number but a different mass number Identified by attaching their mass number to their name U235
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Examples of Atoms Fig. 3-4 p. 48
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Chemical Bonds Chemical formulas show the number of atoms of each type in a compound Contains symbol for each element Uses subscripts to represent the number of atoms Ionic bonds Bonds between oppositely charged ions NaCl (Na+ and Cl-)
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Chemical Bonds Covalent bonds – bonds between uncharged atoms
H2O Hydrogen bonds Weak attraction between molecules of covalent compounds
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Organic vs Inorganic Compounds
contain carbon atoms Held together by covalent bonds Hydrocarbons Carbon and hydrogen methane (CH3) Chlorinated hydrocarbons Carbon, hydrogen, and chlorine DDT (C14H9Cl5) Chlorofluorocarbons (CFCs) Carbon, chlorine, and flourine freon (CCl2F2)
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Organic Compounds Simple carbohydrates Complex carbohydrates Proteins
Carbon, hydrogen, oxygen Simple sugars (C6H12O6) Complex carbohydrates Two or more simple sugars hooked together Proteins Monomers of amino acids linked together
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Genetic Material Nucleic Acids
DNA and RNA Genes – specific sequence of nucleotides in a DNA molecule Fig. 3-6 p. 50
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Organic vs Inorganic Compounds
Lack carbon-carbon or carbon-hydrogen covalent bonds NaCl, H2O, N2O, CO2, NH3
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The Four States of Matter
Solid Liquid Gas Plasma Fig. 3-7 p. 50
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The Four States of Matter
Plasma high energy mixture of positively charged ions and negatively charged electrons sun, stars, lightening
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Matter Quality and Material Efficiency
High-quality matter Concentrated Near the earth’s surface Great potential for use Low-quality matter Dilute Deep underground Little potential as a resource Material efficiency (resource productivity) Total amount of material needed to produce each unit of goods and services
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Energy: What is it? The capacity to do work and transfer heat. Work = force x distance
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Energy: Forms Kinetic energy Potential energy
Energy contained in moving objects Wind, streams, electricity Potential energy Stored energy Stick of dynamite, water behind a dam
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Electromagnetic radiation
Energy radiated in the form of waves as a result of changing electric and magnetic fields Fig. 3-9 p. 52 Ionizing radiation – has enough energy to knock electrons from atoms and change them to positively charged ions. The resulting highly reactive electrons and ions can Disrupt living cells Interfere with body processes Cause many types of sickness, including cancer
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Heat Energy Heat Temperature
The total kinetic energy of all the moving atoms, ions, or molecules within a given substance Temperature Average speed of motion of the atoms, ions, or molecules in a sample of matter at a given moment
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Transfer of Heat Energy
Convection Conduction Radiation Heat from a stove burner causes atoms or molecules in the pan’s bottom to vibrate faster. The vibrating atoms or molecules then collide with nearby atoms or molecules, causing them to vibrate faster. Eventually, molecules or atoms in the pan’s handle are vibrating so fast it becomes too hot to touch. As the water boils, heat from the hot stove burner and pan radiate into the surrounding air, even though air conducts very little heat. Heating water in the bottom of a pan causes some of the water to vaporize into bubbles. Because they are lighter than the surrounding water, they rise. Water then sinks from the top to replace the rising bubbles.This up and down movement (convection) eventually heats all of the water. Fig p. 553
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Energy: Quality High-quality energy concentrated Low-quality energy
dispersed Fig p. 53
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Physical and Chemical Changes
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Matter only changes form
The Law of Conservation of Matter: matter is neither created nor destroyed Matter is not consumed Matter only changes form There is no “away”
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How harmful are pollutants?
Chemical nature of pollutants Concentration Persistence Degradable (nonpersistent) pollution Broken down completely by natural, chemical or biological processes Slowly degradable (persistent) pollution May take decades or longer DDT Nondegradable pollutants Cannot be broken down Lead, mercury, arsenic
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Nuclear Changes – nuclei of isotopes spontaneously change
Natural radioactive decay Unstable isotopes spontaneously emit fast-moving particles, high energy radiation, or both at fixed rates “radioisotopes” Damaging “ionizing” radiation Fig p. 56
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Ionizing Radiation Gamma rays Alpha particles Beta particles
High-energy electromagnetic radiation Alpha particles Fast moving, positively charged chunks of matter Beta particles High speed electrons Fig p. 56
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Ionizing Radiation: Effects
Genetic Damage Mutations or changes in DNA that alter genes and chromosomes Somatic Damage to tissue Burns, eye cataracts, certain cancers Fig p. 56
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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
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Radioactive Decay and Half-life
Half-Lives of Selected Radioisotopes Isotope Radiation Half-Life Emmitted Potassuium-42 12.4 hrs Alpha, beta Iodine-131 8 days Beta, gamma Colbalt-60 5.27 yrs Hydogren-3 tritium 12.5 yrs Beta Strontium-90 28 yrs Carbon-14 5,370 yrs Plutonium-239 24,000 hrs Alpha, gamma Uranium-235 710 million yrs Uranium-238 4.5 billion yrs Time needed for one-half of the nuclei in a radioisotope to emit its radiation (decay) Characteristic half-life for each radioisotope General rule: radioisotopes must be stored for 10 half-lives
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Nuclear Reactions Fission Fig p. 57 Fusion Fig p. 58
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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
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235 92 U n 92 36 Kr 235 92 n U 235 92 n U n 141 56 Ba 92 36 Kr n 92 36 Kr n n n n 235 92 U n 141 56 Ba 92 36 Kr 141 56 n Ba 235 92 U n 235 92 U n 141 56 Ba 235 92 U
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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
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Fuel Reaction Conditions Products D-T Fusion + Neutron Hydrogen-2 or deuterium nucleus + Energy + + + + 100 million ˚C Helium-4 nucleus Hydrogen-3 or tritium nucleus + Proton Neutron
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Laws Governing Energy Changes
First Law of Thermodynamics (Energy) Energy is neither created nor destroyed Energy only changes form You can’t get something for nothing ENERGY IN = ENERGY OUT
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Laws Governing Energy Changes
Second Law of Thermodynamics In every transformation, some energy is converted to heat You cannot break even in terms of energy quality
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Mechanical energy (moving, thinking, living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste heat Waste heat Waste heat Waste heat
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Connections: Matter and Energy Laws and Environmental Problems
High-throughput (waste) economy Matter-recycling economy Low-throughput economy Fig p. 60; see Fig p. 61
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