CHAPTER 2 Science, Matter, Energy, and Systems

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

2. Core Case Study: A Story About a Forest • Hubbard Brook Experimental Forest in New Hampshire • Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site) • Stripped site: • 30-40% more runoff • More dissolved nutrients • More soil erosion

3. The Effects of Deforestation on the Loss of Water and Soil Nutrients Fig. 2-1, p. 31

4. Stepped Art Fig. 2-1, p. 31

5. 2-1 What Do Scientists Do? • Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.

6. Science Is a Search for Order in Nature (1) • Identify a problem • Find out what is known about the problem • Ask a question to be investigated • Gather data through experiments • Propose a scientific hypothesis

7. Science Is a Search for Order in Nature (2) • Make testable predictions • Keep testing and making observations • Accept or reject the hypothesis • Scientific theory: well-tested and widely accepted hypothesis

8. The Scientific Process Fig. 2-2, p. 33

9. Identify a problem Find out what is known about the problem (literature search) Ask a question to be investigated Perform an experiment to answer the question and collect data Scientific law Well-accepted pattern in data Analyze data (check for patterns) Propose a hypothesis to explain data Use hypothesis to make testable projections Perform an experiment to test projections Make testable projections Accept hypothesis Revise hypothesis Test projections Scientific theory Well-tested and widely accepted hypothesis Fig. 2-2, p. 33

10. Find out what is known about the problem (literature search) Ask a question to be investigated Perform an experiment to answer the question and collect data Scientific law Well-accepted pattern in data Analyze data (check for patterns) Propose an hypothesis to explain data Use hypothesis to make testable predictions Perform an experiment to test predictions Accept hypothesis Revise hypothesis Make testable predictions Test predictions Scientific theory Well-tested and widely accepted hypothesis Identify a problem Stepped Art Fig. 2-2, p. 33

11. Testing a Hypothesis Fig. 2-3, p. 33

12. Observation: Nothing happens when I try to turn on my flashlight. Question: Why didn’t the light come on? Hypothesis: Maybe the batteries are dead. Test hypothesis with an experiment: Put in new batteries and try to turn on the flashlight. Result: Flashlight still does not work. New hypothesis: Maybe the bulb is burned out. Experiment: Put in a new bulb. Result: Flashlight works. Conclusion: New hypothesis is verified. Fig. 2-3, p. 33

13. Characteristics of Science…and Scientists • Curiosity • Skepticism • Reproducibility • Peer review • Openness to new ideas • Critical thinking • Creativity

14. Science Focus: Easter Island: Revisions to a Popular Environmental Story • Some revisions to a popular environmental story • Polynesians arrived about 800 years ago • Population may have reached 3000 • Used trees in an unsustainable manner, but rats may have multiplied and eaten the seeds of the trees

15. Stone Statues on Easter Island Fig. 2-A, p. 35

16. Scientific Theories and Laws Are the Most Important Results of Science • Scientific theory • Widely tested • Supported by extensive evidence • Accepted by most scientists in a particular area • Scientific law, law of nature

17. The Results of Science Can Be Tentative, Reliable, or Unreliable • Tentative science, frontier science • Reliable science • Unreliable science

18. Science Has Some Limitations • Particular hypotheses, theories, or laws have a high probability of being true while not being absolute • Bias can be minimized by scientists • Environmental phenomena involve interacting variables and complex interactions • Statistical methods may be used to estimate very large or very small numbers • Scientific process is limited to the natural world

19. Science Focus: Statistics and Probability • Statistics • Collect, organize, and interpret numerical data • Probability • The chance that something will happen or be valid • Need large enough sample size

20. 2-2 What Is Matter? • Concept 2-2 Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.

21. Matter Consists of Elements and Compounds • Matter • Has mass and takes up space • Elements • Unique properties • Cannot be broken down chemically into other substances • Compounds • Two or more different elements bonded together in fixed proportions

22. Gold and Mercury Are Chemical Elements Fig. 2-4a, p. 38

23. Chemical Elements Used in The Book Table 2-1, p. 38

24. Atoms, Ions, and Molecules Are the Building Blocks of Matter (1) • Atomic theory • All elements are made of atoms • Subatomic particles • Protons with positive charge and neutrons with no charge in nucleus • Negatively charged electrons orbit the nucleus • Atomic number • Number of protons in nucleus • Mass number • Number of protons plus neutrons in nucleus

25. Model of a Carbon-12 Atom Fig. 2-5, p. 39

26. 6 protons 6 neutrons 6 electrons Fig. 2-5, p. 39

27. Atoms, Ions, and Molecules Are the Building Blocks of Matter (2) • Isotopes • Same element, different number of protons • Ions • Gain or lose electrons • Form ionic compounds • pH • Measure of acidity • H+ and OH-

28. Chemical Ions Used in This Book Table 2-2, p. 40

29. pH Scale Supplement 5, Figure 4

30. Loss of NO3−from a Deforested Watershed Fig. 2-6, p. 40

31. 60 Nitrate (NO3–) concentration (milligrams per liter) 40 Disturbed (experimental) watershed Undisturbed (control) watershed 20 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 Year Fig. 2-6, p. 40

32. Atoms, Ions, and Molecules Are the Building Blocks of Matter (3) • Molecule • Two or more atoms of the same or different elements held together by chemical bonds • Compounds • Chemical formula

33. Compounds Used in This Book Table 2-3, p. 40

34. Organic Compounds Are the Chemicals of Life • Organic compounds • Hydrocarbons and chlorinated hydrocarbons • Simple carbohydrates • Macromolecules: complex organic molecules • Complex carbohydrates • Proteins • Nucleic acids • Lipids • Inorganic compounds

35. Glucose Structure Supplement 4, Fig. 4

36. Amino Acids and Proteins Supplement 4, Fig. 8

37. Nucleotide Structure in DNA and RNA Supplement 4, Fig. 9

38. DNA Double Helix Structure and Bonding Supplement 4, Fig. 10

39. Fatty Acid Structure and Trigyceride Supplement 4, Fig. 11

40. Matter Comes to Life through Genes, Chromosomes, and Cells • Cells: fundamental units of life; all organisms are composed of one or more cells • Genes • Sequences of nucleotides within DNA • Instructions for proteins • Create inheritable traits • Chromosomes: composed of many genes

41. Cells, Nuclei, Chromosomes, DNA, and Genes Fig. 2-7, p. 42

42. A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. 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. 42

43. A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. 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. Stepped Art Fig. 2-7, p. 42

44. Some Forms of Matter Are More Useful than Others • High-quality matter • Highly concentrated • Near earth’s surface • High potential as a resource • Low-quality matter • Not highly concentrated • Deep underground or widely dispersed • Low potential as a resource

45. Examples of Differences in Matter Quality Fig. 2-8, p. 42

46. 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. 42

47. 2-3 What Happens When Matter Undergoes Change? • Concept 2-3 Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

48. Matter Undergoes Physical, Chemical, and Nuclear Changes • Physical change • No change in chemical composition • Chemical change, chemical reaction • Change in chemical composition • Reactants and products • Nuclear change • Natural radioactive decay • Radioisotopes: unstable • Nuclear fission • Nuclear fusion

49. Types of Nuclear Changes Fig. 2-9, p. 43

50. Radioactive decay Alpha particle (helium-4 nucleus) Radioactive isotope Gamma rays Beta particle (electron) Radioactive decay occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram. Fig. 2-9a, p. 43