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

2. Core Case Study: Carrying Out a Controlled Scientific Experiment  Problem: How does deforestation affect the loss of water and soil nutrients?  1963 - 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. 2-1 What Is Science?  Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.

5. 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 (can only have 1 variable to be tested)  Gather data  Hypothesize  Make testable predictions  Keep testing and making observations  Accept or reject the hypothesis

6. Scientific Method  You want to design an experiment to determine how soil pollution affects elderberry bushes. 1) chose 2 variables Independent (manipulated) Dependent (responding) – must be measurable  concentration of salt vs # elderberries on each bush 2) Write your hypothesis (needs a prediction for both variables)  Increased salt concentrations in soil result in a decrease in the number of berries produced by elderberry bushes.

7. Scientific Method  In addition to your IV and DV, you must include a control. A control is the exact duplicate of the experiment with no manipulation of the IV.  An elderberry bush with no salt added 3) Collect and analyze data Present in data tables and graphs (remember graphing rules!) 4) Draw conclusions that are supported by the data.

8. Science Is a Search for Order in Nature (2)  Important features of the scientific process Curiosity Skepticism Peer review Reproducibility Openness to new ideas

9. Easter Island – do we know what really happened?  Island is located in the S. Pacific, 2,200 miles (3,600 km) off the coast of Chile  Polynesians used canoes to colonize island and then fish.  Islanders thrived and the population increased  Started cutting trees at an unsustainable rate  Used trees for canoes, fires, erecting statues  Once the large trees were gone, no canoes could be made and no one could leave the island.  With trees gone, spring and streams dried up, soil eroded, crops failed and famine occurred.

10.  The islanders started to fight and the population sharply decreased. By the late 1870s, only about 100 people remained.

11. Science Focus: Easter Island: Revisions to a Popular Environmental Story  New scientific data and reevaluation of old data can revise hypotheses.  Some revisions with the Easter Island tragedy Polynesians arrived about 800 years ago, not 2,900 years ago Population may have reached 3000, not 15,000 Determined that the trees were used in an unsustainable manner, but rats may have multiplied and eaten the seeds of the trees Population may have also declined due to contact with visitors/invaders and many were taken to be sold as slaves.

12. Scientists Use Reasoning, Imagination, and Creativity to Learn How Nature Works  Important scientific tools Inductive reasoning- using specific observations to form general conclusions Deductive reasoning – using general observations to form specific conclusions.  Scientists also use Intuition Imagination Creativity

13. 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 – no exceptions  Paradigm shift – a change in thinking when a majority of scientists accept a new framework for theories and laws.

14. Environmental 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  Statistical methods may be used to estimate very large or very small numbers  Environmental phenomena involve interacting variables and complex interactions  Scientific process is limited to the natural world

15. Science Focus: Statistics and Probability  Statistics Collect, organize, and interpret numerical data  Probability The chance that something will happen or be valid

16. 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.

17. 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

18. Atoms, Ions, and Molecules Are the Building Blocks of Matter (1)  Atomic theory – all elements are made of atoms  Subatomic particles Protons (p) with positive charge and neutrons (0) with no charge in nucleus  Negatively charged electrons (e) orbit the nucleus  Atomic number – number of protons in an atom  Mass number Protons plus neutrons EX: Oxygen has 8 p, 8 n and 8 e- What is the mass?

19. Atoms, Ions, and Molecules Are the Building Blocks of Matter (2)  Isotopes – when a particular atom has different numbers of neutrons and therefore different masses Ex: C-12, C-13, C-14  Ions – have electrical charges Gain or lose electrons Form ionic compounds Ex: NaCl, Li 2 S  pH Measure of acidity H + and OH -

20. pH Scale

21. 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 Ex: H 2 0, CO, O 3  Chemical formula

22. Organic Compounds Are the Chemicals of Life  Inorganic compounds- contain 1 atom of C or no atoms of C (except methane CH 4 )  Organic compounds Hydrocarbons and chlorinated hydrocarbons Simple carbohydrates Macromolecules: complex organic molecules Complex carbohydrates Proteins (formed from amino acids) Nucleic acids (DNA, RNA – formed from nucleotides) Lipids

23. Matter Comes to Life through Genes, Chromosomes, and Cells  Cells: fundamental units of life  Genes: sequences of nucleotides within the DNA  Chromosomes: composed of many genes

24. Matter Occurs in Various Physical Forms  Solid  Liquid  Gas

25. Some Forms of Matter Are More Useful than Others  Matter quality is a measure of the usefulness of matter as a resource based on its availability and concentration  High-quality matter- is highly concentrated, found near the earth’s surface and has the potential to be used as a resource. Ex: coal, aluminum can, salt  Low-quality matter- coal fired power plant emissions, aluminum ore, salt water solution

26. 2-3 How Can Matter Change?  Concept 2-3 When matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

27. Matter Undergoes Physical, Chemical, and Nuclear Changes  Physical change – no new substance is formed  Chemical change, chemical reaction- atoms or ions rearrange C + O 2 → CO 2  Nuclear change Natural radioactive decay Radioisotopes: unstable U-235 Types of radiation are alpha, beta and gamma Nuclear fission - splitting apart of the nucleus Nuclear fusion – light elements fuse to make heavier elements. Ex: the sun

28. We Cannot Create or Destroy Matter  Law of conservation of matter  Matter consumption Matter is converted from one form to another So, can we ever really throw something away?

29. 2-4 What is Energy and How Can It Be Changed?  Concept 2-4A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).  Concept 2-4B Whenever energy is changed from one form to another, we end up with lower- quality or less usable energy than we started with (second law of thermodynamics).

30. Energy Comes in Many Forms  Energy- the capacity to do work or transfer heat. Work is done when something is moved. W= fd  Kinetic energy Heat – heat flows from the warmer object to the cooler Transferred by radiation, conduction (when objects are in contact), or convection (movement of heat within liquids and gases) Electromagnetic radiation – energy travels in waves

31. Potential energy - Stored energy Ex: unlit match, gasoline in a tank, food in your pantry. Potential energy can change into kinetic. Ex: burning the gasoline. The PE is stored in the bonds. Energy can be mechanical, chemical, electrical, thermal…

32. Some Types of Energy Are More Useful Than Others  High-quality energy – concentrated energy with a high capacity to do useful work. Ex: nuclear fission, burning gasoline  Low-quality energy – energy is dispersed and has little capacity to do work. Ex: low temperatures

33. Energy Changes Are Governed by Two Scientific Laws  First Law of Thermodynamics (law of the conservation of energy) Energy cannot be created or destroyed 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 In all energy conversions, some waste heat is always produced

34. Energy efficiency or productivity  Ex: Only 6% of the energy from burning gasoline goes into moving the car. The other 94% is released as heat.  Ex: Only 5% of energy used in incandescent lights goes into producing light. The other 95% is released as heat. The energy that becomes light in a CFL is 20%.  Ex: During each step of the food chain, only 10% of the energy is transferred to the next.

35. 2-5 What Are Systems and How Do They Respond to Change?  One approach to ES is to consider earth to be made of many environmental systems. Each part of the system works together to perform a function or set of functions. By considering each system individually, the impact humans have on the environment can by simplified.  Open system- systems that exchange energy and matter across their boundaries.  Closed system- systems that exchange energy but not matter across their boundaries. EX: water cycle

36.  Concept 2-5A Systems have inputs, flows, and outputs of matter and energy, and their behavior can be affected by feedback.  Concept 2-5B Life, human systems, and the earth’s life support systems must conform to the law of conservation of matter and the two laws of thermodynamics.

37. Systems Have Inputs, Flows, and Outputs  System Inputs from the environment Flows, throughputs Outputs

38. Systems Respond to Change through Feedback Loops  Positive feedback loop system continues in the same direction Ex: melting of polar ice amplifies the melting  Negative, or corrective, feedback loop – system changes direction from which it is moving Ex: The more aluminum is recycled, the less aluminum needs to be mined

39. Is the example below a positive or negative feedback loop?  You perspire on a hot day.  This is a negative feedback loop.  You perspire because your skin gets hot. Perspiration evaporates from the surface of your skin and your skin surface temperature decreases. Evaporation is a cooling process!

40. 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  Tipping point, threshold level Causes a shift in the behavior of a system

41. System Effects Can Be Amplified through Synergy  Synergistic interaction, synergy (when the combined effect is greater than the sum of the separate effects) Helpful Ex: getting a group of people to write letters Harmful Ex: Smoking (10x more likely to get lung cancer) and inhaling asbestos particles 5x more likely to get cancer) But exposure to both increases the likelihood by 50x!

42. Human Activities Can Have Unintended Harmful Results  Deforested areas turning to desert  Coral reefs dying  Glaciers melting  Sea levels rising