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

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Presentation on theme: "Science, Matter, Energy, and Systems Chapter 2 – Part 1 Scientific Process."— Presentation transcript:

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

3 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)

4 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

5 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

6 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????

7 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

8 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.

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

10 Nature of Science  Hypothesis Proposed scientific explanation for a set of observations  A good hypothesis must: 1.Be testable. 2.Be a statement, not a question. 3. Predict cause and effect. If… then…

11 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…

12 Able to Change 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?"

13 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.

14 Independent Variable – 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.

15 Dependent Variable – 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.

16 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

17 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.

18 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.

19 Able to Change 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

20 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.

21 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

22 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.

23 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?  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?

24 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

25 Your Turn!  Case of the Ivory Billed Woodpecker  woodpecker.html woodpecker.html

26 The Case of the Ivory Billed Woodpecker  Case of the Ivory Billed Woodpecker  woodpecker.html woodpecker.html

27 The Case of the Ivory Billed Woodpecker

28 Wisconsin Fast Plants Laboratory Project 1.Make a list of questions you have about plants. Be creative! 2.Suggested IV: Fertilizer Crowding Acid (vinegar) Soil Glucose

29 Your Turn: Wisconsin Fast Plant Project! 1.On your paper include the following information: 1.Question 2.Hypothesis 3.Null Hypothesis 4.Experimental Design 1.Independent and Dependent Variable 2.Control and Experimental Groups 3.Levels 4.Constants 5.Sample Size 5.Detailed Procedure

30 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?

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

32 Matter Any substance that:  Occupies space  Has mass  Is made of atoms

33 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

34 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

35 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…

36 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

37 Organic Compounds Are the Chemicals of Life  Inorganic compounds  Organic compounds Macromolecules: complex organic molecules Carbohydrates Proteins Nucleic acids Lipids

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

39

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41 Example: Carbon Atomic Number = 6 6 Protons 6 Electrons Atomic Mass = – 6 = 6 6 Neutrons

42 Your Turn!  Atomic Mass #...

43 ELECTRONEGATIVITY  The tendency of an atom to attract electrons to itself when it is bonded to another atom

44 Increase

45 BONDING OPTIONS COVALENT BOND  By sharing electrons (small difference in EN) IONIC BOND  By transferring electrons (producing ions) (big difference in EN)

46 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

47 Chemical Bonding

48 Covalent Bonds  Sharing of electrons Electrons travel in the orbitals of both atoms  Each atom fills out the outermost energy level

49 Water: A Covalent Bond

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

51 Ionic Bond  Ion = charged particle Anion = negatively charged Cation = positively charged  Strong attraction between oppositely charged ions forms the ionic bond

52 Ionic Bond

53 Trick to Remember!  If an atom GAINS electrons, its overall charge becomes more negative.  If it LOSES electrons, its charge becomes more positive

54 Your Turn!  Bonding Practice  Covalent: Carbon and Chlorine  Ionic: Sodium and Chlorine

55 Science, Matter, Energy, and Systems Chapter 2 – Part 3 Water

56 Why is it important?  Covers ¾ of Earth’s surface! Most abundant compound in most living things  Exceptional substance with many extraordinary qualities!

57 Unusual Properties  Determine characteristics of: Atmosphere Ocean Land

58 Water’s Structure…Simple?  Hydrogen 1 electron…needs 2  Oxygen 6 electrons (outer shell)…needs 8  Covalent Bonding

59 Polar Molecule  Charges are unevenly distributed Partial positive Partial negative  Electronegativites of atoms differ

60 Electronegativity

61 Hydrogen Bonds  Attraction between two different molecules  “weak” bond  Not “real” bond b/c no sharing or transferring of electrons Ex: water, proteins, & DNA

62 How many hydrogen bonds can each water molecule form?

63 As one hydrogen bond is broken another one forms  Each bond lasts trillionths of a second  Substantial percentage bonded to neighbor

64 Cohesion  Attraction between molecules of the same substance  Causes molecules on the surface of water to be drawn inward Why water forms beads on smooth surfaces Why insects can walk on water

65 Surface Tension  Result of cohesion  How it “stretches or resists breaking”  Water molecules form weak elastic membrane Water to water Water to air

66 Adhesion  Attraction between molecules of different substances Meniscus Water to WaterWater to Glass

67 Capillary Action  Forces that draw water out of the roots of a plant and up into its stems and leaves  Holds column of water together as it rises  Cohesion and adhesion

68 Density  Less dense as a solid  Hydrogen bonds stay connected less energy in system so bonds don’t break  More space occurs between water molecules

69 Solutions  All components are evenly distributed throughout Solute – substance that is dissolved Solvent – the substance in which the solute dissolves  Due to water’s polarity Can dissolve ionic compounds and other polar molecules

70 Solubility  Water surrounds the charged ends and separates the molecules

71 Suspensions  Mixtures of water and nondissolved material Materials don’t dissolve but separate into pieces so small that they do not settle out  Example Blood

72 Your Turn!  Water Property Lab

73 Science, Matter, Energy, and Systems Chapter 2 – Part 4 Isotopes and Nuclear Reactions

74 Isotopes  Number of neutrons can vary from one atom of an element to another Changes atomic mass, not atomic number  Atomic number NEVER changes

75 Isotopes H = hydrogen 1 1 H = deuterium H = tritium Identified by mass #

76 Isotopes  Isotopes have SAME number of protons but DIFFERENT numbers of neutrons Heavier Behave identical in chemical reactions  Same # electrons = same chemical properties

77 Radioactive Isotopes  Diagnose and treat diseases Cardiovascular disease Cancer radiation  Sterilize foods Kill bacteria Preserve food  Measure the ages of certain rocks Fossils

78 Matter Undergoes Physical, Chemical, and Nuclear Changes  Nuclear change – changes in the nuclei of atoms Nuclear fission – nucleus splits and releases neutrons plus energy

79 Matter Undergoes Physical, Chemical, and Nuclear Changes  Nuclear change – changes in the nuclei of atoms Nuclear fission – nucleus splits and releases neutrons plus energy Nuclear fusion – two nuclei fuse together and release energy

80 Nuclear Power 6:51

81 Light-Water-Moderated and -Cooled Nuclear Power Plant with Water Reactor

82 After 3 or 4 Years in a Reactor, Spent Fuel Rods Are Removed and Stored in Water

83 Science, Matter, Energy, and Systems Chapter 2 – Part 5 pH

84 What do vinegar, lemons, and orange juice have in common?

85 Characteristics of Acids  Taste Sour  React with metals  Often produce hydrogen gas  Can burn your skin

86 What do milk, Comet, and Tums have in common?

87 Characteristics of Bases  Taste Bitter  Feel Slippery  Neutralize Acids Antacids  Dissolve grease

88 But, what exactly are acids and bases?

89  Substance that ionizes in water to give hydrogen ions (H + ) Acid

90 Examples of Acids  HCl  H 2 SO 4  HNO 3  HF  Juices

91  Substance that ionizes in water to give hydroxide ions (OH - ) Base

92 Examples of Bases  NaOH  Ca(OH) 2  KOH  Soap, Ammonia, Baking Soda

93 The pH Scale  Measurement system that indicates the concentration of H + ions in solution. The pH scale ranges from 0 to 14.

94 The pH Scale  pH = “power of hydrogen” Each step increases by a power of ten

95 pH Scale

96 pH Calculations  Remember: For every one-increment change in pH, the ions change by a factor of 10.  Example: What is the difference in H+ concentration between pH 6 and pH 4? pH 6 – pH 4 = pH 2 H+ is 100 times more concentrated in the pH 4 solution

97 pH Calculations  Remember: Concentration of H+ and OH- always equals M or pH 14  Example: [H+] = M pH is 6: weak acid [OH-] = M

98 pH and Water WWhy does water have a pH of 7? Hydronium ions = hydroxide ions (H + ) = (OH - ) H 2 0H + + OH -

99 Interesting fact… Water can act as an acid or a base!!!

100 Interesting fact…  Amphoteric - substance that can act as either an acid or a base.

101 Your Turn!  Review of pH Calculations

102 pH Scale

103 Your Turn…pH of natural substances  Substances: Soil Freshwater Saltwater Rainwater  Tools: Soil – capsules Water (use 2 of the following) - pH meter, litmus paper, or microkit

104 Your Turn…pH of natural substances CapsulespH MeterLitmus Paper Microkit Soil Freshwater Saltwater Rainwater

105 Buffers  Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.

106 Buffers are working while you exercise!

107 Ocean pH  Surface water pH ranges from 8.0 to 8.3 Average 8.1  Ocean water combines with CO 2  Forms weak Carbonic Acid H CO 2 H 2 CO 3 H + + HCO 3 -

108 Ocean pH AAverage pH 8.1 BASIC? CCarbonic Acid? Why is the ocean pH slightly basic when CO 2 (an acid ) is added?

109 Carbonate Buffering  Keeps ocean pH about same (8.1)  pH too high, carbonic acid releases H+  pH too low, bicarbonate combines with H+ H 2 CO 3 H + + HCO 3 - HCO H + H 2 CO 3

110 Carbonate Buffering  Marine organisms die and sink into deep ocean Calcium carbonate in shell neutralizes acid through buffering CaCO 3 CO H + HCO H + H 2 CO 3

111 Carbonate Buffering  Dead mollusks are the antacids of the sea!

112 Carbonate buffering

113

114 Recent Decrease in Ocean Acidity  Excess carbon dioxide in atmosphere 33% CO 2 released by burning fossil fuels ends up in ocean  Overwhelming oceans natural ability to buffer itself pH has decreased 0.1 since preindustrial times

115 Recent Decrease in Ocean Acidity  More difficult for certain marine creatures to build hard parts out of calcium carbonate Plankton Corals  Alter food chain of ocean!

116 Science, Matter, Energy, and Systems Chapter 2 – Part 6 Thermodynamics

117 Energy Comes in Many Forms  Kinetic energy - energy of motion Mass and velocity! Electromagnetic radiation of waves Short = greater energy

118 Kinetic energy  Atoms and molecules in any gas, liquid, or solid are always in motion Vibrate around average position  Kinetic Energy = ½ (mass)(velocity) 2

119 Temperature  Measure of the average kinetic energy of the atoms and molecules in the substance  Measured in degrees Celsius Fahrenheit Kelvin

120 Heat  Measure of total kinetic energy of the atoms and molecules in a substance  Measured in calories

121 Calorie  Amount of heat needed to raise the temperature of 1g of water by 1 o C  1 food Calorie (1 kilocalorie) = 1000 calories

122 What’s the difference?  Which has greater average Kinetic Energy? Higher Temperature?  Which has greater total Kinetic Energy? More Heat?

123 Energy Comes in Many Forms  Potential energy - energy of position Stored energy; can be changed into kinetic energy Examples: rock held in hand, unlit match, gasoline

124 Some Types of Energy Are More Useful Than Others  Energy quality - measure of an energy source’s capacity to do useful work  High-quality energy – concentrated energy that has a high capacity to do useful work High-temperature heat Concentrated sunlight High velocity wind

125 Some Types of Energy Are More Useful Than Others  Energy quality - measure of an energy source’s capacity to do useful work  Low-quality energy – energy that is dispersed and has little capacity to do useful work Low temperatures

126 Energy Changes Are Governed by Two Scientific Laws  First Law of Thermodynamics Energy input always equals energy output  Second Law of Thermodynamics Energy always goes from a more useful to a less useful form when it changes from one form to another Decreased energy efficiency

127 Life application  94% of the money you spend for gasoline is not used to transport you anywhere!

128 The Second Law of Thermodynamics in Living Systems

129 Your Turn!  Potential vs. Kinetic worksheet

130 Science, Matter, Energy, and Systems Chapter 2 – Part 7 Systems

131 Systems Have Inputs, Flows, and Outputs  System – set of components that function and interact in some regular way Inputs from the environment Flows, throughputs Outputs

132 Systems Respond to Change through Feedback Loops  Positive feedback loop - causes a system to change in the same direction

133 Systems Respond to Change through Feedback Loops  Negative feedback loop – causes a system to change in the opposite direction from which it is moving Opposing process  Can promote sustainability! Aluminum mining  can  recycling

134 Video Clip – Planet Earth Forests  Cicada Life Cycle  21:00-26:00

135 Time Delays Can Allow a System to Reach a Tipping Point  Time delays vary Between the input of a feedback stimulus and the response to it Example: Planting trees  Tipping point, threshold level Causes a shift in the behavior of a system

136 System Effects Can Be Amplified through Synergy  Synergistic interaction – two or more processes interact so that the combine effect is greater than the sum of their separate effects Helpful E.g., campaign vs. individual persuasion Harmful E.g., Smoking and inhaling asbestos particles


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