Chapter 2

1. Chapter 2 Science, Systems, Matter, and Energy

2. 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?

3. 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?

4. Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. • InfoTrac: Underwater Microscope Finds Biological Treasures in Subtropical Ocean. Ascribe Higher Education News Service, June 26, 2006. • InfoTrac: In Bacterial Diversity, Amazon Is a 'Desert'; Desert Is an 'Amazon'. Ascribe Higher Education News Service, Jan 9, 2006. • InfoTrac: Making MGP wastes beneficial. Bob Paulson. Pollution Engineering, June 2006 v38 i6 p20(5). • NASA: Nitrogen Cycle • Environmental Literacy Council: Phosphorous Cycle • National Sustainable Agriculture Information Service: Nutrient Cycles

5. Video: The Throw Away Society • This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.

6. 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

7. THE NATURE OF SCIENCE • What do scientists do? • Collect data. • Form hypotheses. • Develop theories, models and laws about how nature works. Figure 2-2

8. Ask a question Do experiments and collect data Interpret data Well-tested and accepted patterns in data become scientific laws Formulate hypothesis to explain data Do more experiments to test hypothesis Revise hypothesis if necessary Well-tested and accepted hypotheses become scientific theories Fig. 2-2, p. 29

9. Ask a question Do experiments and collect data Interpret data Well-tested and accepted patterns In data become scientific laws Formulate hypothesis to explain data Do more experiments to test hypothesis Revise hypothesis if necessary Well-tested and accepted hypotheses become scientific theories Stepped Art Fig. 2-3, p. 30

10. 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

11. Research results Scientific paper Peer review by experts in field Paper rejected Paper accepted Paper published in scientific journal Research evaluated by scientific community Fig. 2-3, p. 30

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. 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).

18. 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.

19. 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.

20. Atoms Figure 2-4

21. 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-)

22. The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution. Figure 2-5

23. 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).

24. 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.

25. 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)).

26. 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

27. (a) Prokaryotic Cell DNA(information storage, no nucleus) Cell membrane (transport of raw materials and finished products) Protein construction and energy conversion occur without specialized internal structures Fig. 2-6a, p. 37

28. (b) Eukaryotic Cell Nucleus (information storage) Energy conversion Protein construction Cell membrane (transport of raw materials and finished products) Packaging Fig. 2-6b, p. 37

29. 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

30. 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. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Fig. 2-7, p. 38

31. 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. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Stepped Art Fig. 2-7, p. 38

32. 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).

33. 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

34. High Quality Low Quality Solid Gas Solution of salt in water Salt Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum can Aluminum ore Fig. 2-8, p. 39

35. 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.

36. Chemical Change • Energy is given off during the reaction as a product.

37. Reactant(s) Product(s) energy carbon dioxide carbon + oxygen + energy + O2 C CO2 + energy + + black solid colorless gas colorless gas p. 39

38. 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

39. Nuclear Changes: Radioactive Decay • Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of matter (alphaorbeta 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).

40. 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

41. Uranium-235 Uranium-235 Uranium-235 Energy Fission Fragment Uranium-235 n n Neutron n n Uranium-235 Energy Energy n n Uranium-235 Fission Fragment Uranium-235 Energy Uranium-235 Uranium-235 Uranium-235 Fig. 2-9, p. 41

42. Uranium-235 Uranium-235 Uranium-235 Energy Fission fragment Uranium-235 n n n Neutron n Energy Energy Uranium-235 n Uranium-235 n Fission fragment Uranium-235 Energy Uranium-235 Uranium-235 Uranium-235 Stepped Art Fig. 2-6, p. 28

43. 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

44. Reaction Conditions Products Fuel Proton Neutron Energy Hydrogen-2 (deuterium nucleus) + 100 million °C + Helium-4 nucleus + + Hydrogen-3 (tritium nucleus) Neutron Fig. 2-10, p. 42

45. 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

46. Electromagnetic Spectrum • Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content. Figure 2-11

47. Sun Ionizing radiation Nonionizing radiation Near infrared waves Far infrared waves Near ultra- violet waves Far ultra- violet waves Cosmic rays Gamma Rays Visible Waves TV waves Radio Waves X rays Micro- waves High energy, short Wavelength Wavelength in meters (not to scale) Low energy, long Wavelength Fig. 2-11, p. 43

48. Electromagnetic Spectrum • Organisms vary in their ability to sense different parts of the spectrum. Figure 2-12

49. Energy emitted from sun (kcal/cm2/min) Visible Infrared Ultraviolet Wavelength (micrometers) Fig. 2-12, p. 43

50. Relative Energy Quality (usefulness) Source of Energy Energy Tasks Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Dispersed geothermal energy Low-temperature heat (100°C or lower) Low-temperature heat (100°C or less) for space heating Fig. 2-13, p. 44