Science, Matter, Energy, and Systems

1. Science, Matter, Energy, and Systems Chapter 2 – Part 1 Scientific Process

2. Core Case Study: Carrying Out a Controlled Scientific Experiment • F. Herbert Bormann, Gene Likens, et al.: Hubbard Brook Experimental Forest in NH (U.S.) • Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)

3. The Effects of Deforestation on the Loss of Water and Soil Nutrients • Built v-shaped dams across the creeks at the bottom of forested valleys • Measured amounts of water and dissolved plant nutrients

4. The Effects of Deforestation on the Loss of Water and Soil Nutrients • Investigators cut down all trees and shrubs in one valley • Sprayed area with herbicides to prevent regrowth

5. The Effects of Deforestation on the Loss of Water and Soil Nutrients • Amount of water flowing out of the deforested valley increased by 30-40% • Eroded soil • Removed 6x more nutrients from soil • Conclusions????

6. Scientists Use Reasoning, Imagination, and Creativity to Learn How Nature Works Important scientific tools Inductive reasoning – involves using specific observations and measurements Specific  General Deductive reasoning – involves using logic to arrive at a specific conclusion based on a generalization or premise General  Specific

7. Inductive or Deductive? All birds have feathers.  Eagles are birds.  Eagles have feathers. A meatball falls to the ground when dropped from a height of 10 feet.  An olive falls to the ground when dropped from a height of 2 feet.  All objects fall to the Earth’s surface when dropped. Deductive Inductive

8. Nature of Science • An organized way of using evidence to learn about the natural world • Observations • Hypothesis • Experiment • Results • Conclusion • Repeating • Peer Review

9. Nature of Science Hypothesis Proposed scientific explanation for a set of observations A good hypothesis must: Be testable. Be a statement, not a question. 3. Predict cause and effect. If… then…

10. Nature of Science • Null Hypothesis: • States that the variable will have no effect on the outcome of the experiment • Example: Light intensity has no effect on plant growth. • Allows conclusions to be drawn that “reject” or “fail to reject” the null hypothesis If… then…

11. Change Able to Variable • Every experiment measures two • Independent variable -- the variable that the experimenter controls. • answers the question "What do I change/control?" • Dependent variable -- the variable the experimenter measures (results). • answers the question "What do I observe/measure?"

12. Scenario • A group of students is assigned a populations project in their APES class. They decide to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

13. IndependentVariable – What do I control ? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

14. DependentVariable – What do I measure? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

15. Controlled Experiment • Experimental group - group that receives treatment in a controlled experiment. • Contains Independent Variable • Control group - group that does not receive treatment in a controlled experiment. • Does not contain Independent Variable

16. Experimental Group– Which group has the IV? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

17. Control – Which group doesn’t have the IV? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

18. Change Able to Variable • Levels – measure of your independent variable • Example: • Number of seeds in a pot • Number of fish in a fish bowl • Number of times that an action is repeated

19. Levels – how is the IV measured? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

20. Controlled Experiment • Constant • What remains constant between experimental groups • Trials • Number of times you repeat an experiment • More tries = more reliable results • Sample size • The number of objects or events studied

21. Constants – What do I keep the same? • A group of students is assigned a populations project in their APES class. They decided to determine the effect of sunlight on radish plant height. They set up 3 clay pots, each one containing 12 radish plants, 100g of potting soil, and given 25 mL of water daily. The pots are all 4 inches in diameter. One pot is placed in 24 hours darkness, one in 12 hours sunlight/12 hours darkness, and the last in 24 hours sunlight. After 5 days, they measure the height of all the plants in each pot.

22. Not all experiments are created equal… • Frontier science – preliminary testing • Reliable science – well supported and studied experiments • High probability of being true • Unreliable – unsupported via peer review • Critical Thinking Questions: • Was the experiment controlled? • Have the data been verified? • Have the results been reproduced by other scientists? • Are the investigators unbiased? • Have the conclusions been verified by impartial peer review?

23. Scientific Theories and Laws • Theory • Verified, credible and widely accepted hypothesis • Make future predictions • Law • Mathematical description of what a theory explains • Paradigm Shift • Majority of scientists in a field accept a new framework for theories and laws

24. Your Turn! • Case of the Ivory Billed Woodpecker • http://www.pbs.org/wgbh/nova/nature/ivory-billed-woodpecker.html

25. The Case of the Ivory Billed Woodpecker • Case of the Ivory Billed Woodpecker • http://www.pbs.org/wgbh/nova/nature/ivory-billed-woodpecker.html

26. The Case of the Ivory Billed Woodpecker

27. Wisconsin Fast Plants Laboratory Project • Make a list of questions you have about plants. • Be creative! • Suggested IV: • Fertilizer • Crowding • Acid (vinegar) • Soil • Glucose

28. Your Turn: Wisconsin Fast Plant Project! • On your paper include the following information: • Question • Hypothesis • Null Hypothesis • Experimental Design • Independent and Dependent Variable • Control and Experimental Groups • Levels • Constants • Sample Size • Detailed Procedure

29. Peer Review • Is the hypothesis testable, a statement, and does it predict a cause and effect relationship? • Will the data be quantitative rather than qualitative? • Are there any unaccounted for variables? If so, what are they? • Is the procedure logical? • Any remaining questions or comments?

30. Science, Matter, Energy, and Systems Chapter 2 – Part 2 Chemical Bonding

31. Matter Any substance that: • Occupies space • Has mass • Is made of atoms

32. Some Forms of Matter Are More Useful than Others • Matter quality – measure of how useful a form of matter is to humans as a resource • Based on availability and concentration

33. Some Forms of Matter Are More Useful than Others • High-quality matter • highly concentrated • Near the Earth’s surface • Great potential as a resource • Low-quality matter • Not highly concentrated • Located deep underground or ocean • Little potential for use

34. We Cannot Create or Destroy Matter • Matter consumption • Matter is converted from one form to another • Law of conservation of matter – matter cannot be created nor destroyed Everything we think we have thrown away remains here with us in some form…

35. Matter Consists of Elements and Compounds • Elements • Unique properties • Cannot be broken down chemically into other substances • SPONCH • Compounds • Two or more different elements bonded together in fixed proportions

36. Organic Compounds Are the Chemicals of Life • Inorganic compounds • Organic compounds • Macromolecules: complex organic molecules • Carbohydrates • Proteins • Nucleic acids • Lipids

37. Atomic Composition • No unique substances in living things, just different amounts • “Same ingredients, different recipes.”

40. Example: Carbon • Atomic Number = 6 • 6 Protons • 6 Electrons • Atomic Mass = 12 • 12 – 6 = 6 • 6 Neutrons

41. Your Turn! • Atomic Mass #...

42. ELECTRONEGATIVITY • The tendency of an atom to attract electrons to itself when it is bonded to another atom

43. Increase Increase

44. BONDING OPTIONS COVALENT BOND • By sharing electrons (small difference in EN) IONIC BOND • By transferring electrons (producing ions) (big difference in EN)

45. Chemical Bonding • Atoms combine according to certain rules • Rules determined by the number of electrons found in the outermost energy level • First energy level = 2 electrons • Second energy level = 8 electrons • Third energy level = 8 electrons

46. Chemical Bonding

47. Covalent Bonds • Sharing of electrons • Electrons travel in the orbitals of both atoms • Each atom fills out the outermost energy level

48. Water: A Covalent Bond

49. Ionic Bonds • Transfer of electrons • Ex. NaCl • Sodium has one electron in outer shell Na + • Chlorine has seven electrons in its outer shell Cl –

50. Ionic Bond • Ion = charged particle • Anion = negatively charged • Cation = positively charged • Strong attraction between oppositely charged ions forms the ionic bond