Science. Matter. Energy. Systems.

1. Science. Matter. Energy. Systems. • Chapter 2 1

2. Important Definitions to Review • Science – knowledge of how the world works • Technology – creation of new processes intended to improve the quality of life • Law – certain phenomena always act in a predictable manner • Theory – rational explanation for numerous observations of a certain phenomena – global warming due to greenhouse effect • Accuracy – measurement agrees with the accepted correct value • Precision – measure of reproducibility • Inductive reasoning- using observations and facts to arrive at generalizations • Deductive reasoning - using logic to arrive at a specific conclusion 2

3. Scientific method • identify question/problem • HYPOTHESIS – proposed to explain observed patterns • Complete experiment and collect data • Analysis and conclusions (results tentative, reliable or unreliable) • Experiments subject to peer review • identify biases • Identify limitations 3

4. Systems • system: set of components that interact in some regular way • Open system: systems the exchange both energy and matter across their boundaries • most environmental systems open • Inputs - matter, energy, information • Throughput - flow of input • Output - matter, energy, information flowing out • Closed system: exchange energy but not matter across their boundaries • ex. water cycle • feedback loop: Change in one part of a system influences another part of the system 4

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6. Positive feedback loop • causes a system to change further in the same direction. (farther from normal) • Exponential growth of population – more individuals lead to increased number of births • Precipitation causes erosion. Erosion causes plants to die. More precipitation causes more erosion and more vegetation death. 6

7. Negative feedback loop • system to change in the opposite direction from which it is moving (closer to normal) • Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating 7

8. Implications for the environment – High waste society 8

9. Implications for the environment – Low waste society 9

10. Complex systems • Time lags – change in a system leads to other changes after a delay • lung cancer • Resistance to change – built in resistance – • political, economic • Synergy-when two or more processes interact so that the combined effect is greater • Can be beneficial or harmful • Chaos – unpredictable behavior in a system 10

11. Matter and Energy Resources • Nature’s Building Blocks • anything that has mass and takes up space 11

12. Forms of matter • elements – single type of atoms • 110 elements • 92 natural, 18 synthesized • table 2.1 (important elements) • compounds - 2 or more elements, held together by chemical bonds • table 2.3 (important compounds) 12

13. Atomic Theory Definitions • atoms - smallest units of matter- protons (+), neutrons (0), electrons (-) • protons/neutrons in nucleus of atom • atomic # = # of protons • isotope: same atomic number but different mass number (different form of the same element) • Carbon-14; Uranium-235 • ion - electrically charged atoms • Table 2.2 (important ions) • molecules - combinations of atoms of the same or different elements 13

14. Some Important elements composition by weight – only 8 elements make up 98.5% of the Earth’s crust 14

15. Organic Compounds • with 2 or more atoms of carbon • hydrocarbons: carbon and hydrogen atoms • methane CH4 (only exception to 2 C rule) • Octane C8H18 • chlorinated hydrocarbons: carbon, hydrogen and chlorine • DDT C14H9Cl5 • Simple carbohydrates: carbon, hydrogen and oxygen • glucose C6H12O6 • Also includes Polymers. • complex carbohydrates (made of simple sugars), nucleic acids (made of nucleotides), proteins (made of amino acids) and lipids 15

16. Inorganic compounds • no carbon, not originating from a living source • Earth’s crust – minerals, water • water, nitrous oxide, nitric oxide, sodium chloride, ammonia 16

17. Matter quality • Measure of how useful a matter is for humans based on availability and concentration 17

18. Energy • capacity to do work and transfer heat • Kinetic Energy -energy in action • electromagnetic radiation (energy in waves resulting from electrical/magnetic fields), heat (energy in moving atoms) • Potential energy - stored energy that is potentially available; may be changed to kinetic 18

19. Electromagnetic radiation • different wave lengths • Shorter wavelength= high energy • disrupts cells with long term exposure 19

20. Energy sources • 99% of the energy that supports earth comes from the sun • without it earth’s temperature -240 C or -400 F • allows for wind, hydro and biomass sources of renewable energy • 1% - commercial sources. Burning oil, coal and natural gas. 20

21. Energy quality • Measure of how useful an energy source is in terms of concentration and ability to perform useful work 21

22. Energy Changes • energy changes governed by 2 scientific laws • law of conservation of energy (first law of thermodynamics) • no energy is created or destroyed as it changes from one form to another • energy input = energy output • can lose energy quality (converted to a less useful form) • second law of thermodynamics • as energy changes form we end up with a lower quality or less usable energy source (heat) 22

23. Nuclear Changes • nuclei of certain isotopes spontaneously change (radioisotopes) or made to change into one or more different isotopes • Occurs with one of the following particles: • Alpha particles – fast moving (2 protons+2 neutrons) • Beta particles – high speed electrons • Gamma particles - high energy electromagnetic radiation • radioactive decay, nuclear fission, nuclear fusion 23

24. Use….radioisotopes • Estimate age of rocks and fossils • Tracers in pollution detection and medicine • Genetic control of insects 24

25. Half – Life (radioactive decay) • time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation. • ranges from fraction of a second to millions of years 25

26. Nuclear Fission • certain isotopes (uranium-235) split apart into lighter nuclei + neutrons when struck by neutrons • chain reaction releases energy • Releases an enormous amount of energy very quickly 26

27. Nuclear fusion • two isotopes (hydrogen) forced together at extremely high temperatures (100 million C) • Fuse to form a heavy nucleus and release a tremendous amount of energy 27