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CHAPTER 2

CHAPTER 2. SCIENCE, MATTER, ENERGY & SYSTEMS. Matter Consists of Elements & 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.

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CHAPTER 2

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  1. CHAPTER 2 SCIENCE, MATTER, ENERGY & SYSTEMS

  2. Matter Consists of Elements & 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

  3. Atoms, Ions, & Molecules Are the Building Blocks of Matter • 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

  4. Atoms, Ions, & Molecules Are the Building Blocks of Matter, cont. • Isotopes • Same element, different number of neutrons • Ions • Gain or lose electrons • Form ionic compounds • pH • Measure of acidity • H+ and OH-

  5. pH Scale Supplement 5, Figure 4

  6. Compounds Important to Life • Inorganic compounds — simple molecules that usually consist of one or two different elements; for example: • Water (H2O) • Carbon dioxide (CO2) • Bimolecular oxygen (O2) • Sodium chloride (NaCl) • Organic compounds — substances that contain covalently-bonded carbon and hydrogen and often other elements; for example: • Sugars • Lipids • Amino acids • Proteins

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

  8. 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 has the opposite qualities

  9. Matter Undergoes Physical, Chemical, & Nuclear Changes • Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter). • 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

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

  11. Energy Comes in Many Forms • Kinetic energy • Flowing water • Wind • Heat • Transferred by radiation, conduction, or convection • Electromagnetic radiation • Potential energy • Stored energy • Can be changed into kinetic energy • Sun provides 99% of earth’s energy • Warms earth to comfortable temperature • Plant photosynthesis • Winds • Hydropower • Biomass • Fossil fuels: oil, coal, natural gas

  12. Energy Changes Are Governed by Two Scientific Laws • First Law of Thermodynamics (Law of Conservation of Energy) • Energy is neither created nor destroyed in physical and chemical changes • Second Law of Thermodynamics • Energy always goes from a more useful to a less useful form when it changes from one form to another

  13. Energy Changes Are Governed by Two Scientific Laws • Incandescent light bulbs and internal combustion engines are very inefficient: produce wasted heat • Cellular respiration in mammals and birds is far less efficient than in amphibians, reptiles, insects & other members of the animal kingdom • Ex: Mammals typically consume five to 10 times (depends on the conditions) the amount of food energy as a reptile to maintain life processes

  14. Systems Have Inputs, Flows, & Outputs • System • Set of components that interact in a regular way • Human body, earth, the economy • Inputs from the environment • Flows (throughputs) of matter and energy • Outputs to the environment

  15. Inputs, Throughput, & Outputs of an Economic System Fig. 2-17, p. 48

  16. Systems Respond to Change through Feedback Loops • Positive feedback loop • Causes system to change further in the same direction • Can cause major environmental problems • Negative, or corrective, feedback loop • Causes system to change in opposite direction

  17. Positive vs. Negative Feedback Loops Positive Negative

  18. Decreasing vegetation... ... which causes more vegetation to die. ... leads to erosion and nutrient loss... Positive Feedback Loop Fig. 2-18, p. 49

  19. House warms Temperature reaches desired setting and furnace goes off Furnace on Furnace off House cools Negative Feedback Loop Temperature drops below desired setting and furnace goes on Fig. 2-19, p. 50

  20. Time Delays & Tipping Points • 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 • Melting of polar ice • Population growth

  21. System Effects Can Be Amplified through Synergy • Synergistic interaction, synergy • Two or more processes combine in such a way that combined effect is greater than the two separate effects • Helpful • Studying with a partner • Harmful • E.g., Smoking and inhaling asbestos particles

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