Chapter 2 Science, Systems, Matter, and Energy

Chapter Overview Questions  What is science, and what do scientists do?  What are major components and behaviors of complex systems?  What are the basic forms of matter, and what makes matter useful as a resource?  What types of changes can matter undergo and what scientific law governs matter?

Chapter Overview Questions (cont’d)  What are the major forms of energy, and what makes energy useful as a resource?  What are two scientific laws governing changes of energy from one form to another?  How are the scientific laws governing changes of matter and energy from one form to another related to resource use, environmental degradation and sustainability?

THE NATURE OF SCIENCE  What do scientists do? Collect data. Collect data. Form hypotheses. Form hypotheses. Develop theories, models and laws about how nature works. Develop theories, models and laws about how nature works. Figure 2-2

Scientific Theories and Laws: The Most Important Results of Science  Scientific Theory Widely tested and accepted hypothesis. Widely tested and accepted hypothesis.  Scientific Law What we find happening over and over again in nature. What we find happening over and over again in nature. Figure 2-3

Testing Hypotheses  Scientists test hypotheses using controlled experiments and constructing mathematical models. Variables or factors influence natural processes Variables or factors influence natural processes Single-variable experiments involve a control and an experimental group. Single-variable experiments involve a control and an experimental group. Most environmental phenomena are multivariable and are hard to control in an experiment. Most environmental phenomena are multivariable and are hard to control in an experiment. Models are used to analyze interactions of variables.Models are used to analyze interactions of variables.

Scientific Reasoning and Creativity  Inductive reasoning Involves using specific observations and measurements to arrive at a general conclusion or hypothesis. Involves using specific observations and measurements to arrive at a general conclusion or hypothesis. Bottom-up reasoning going from specific to general. Bottom-up reasoning going from specific to general.  Deductive reasoning Uses logic to arrive at a specific conclusion. Uses logic to arrive at a specific conclusion. Top-down approach that goes from general to specific. Top-down approach that goes from general to specific.

Frontier Science, Sound Science, and Junk Science  Frontier science has not been widely tested (starting point of peer-review).  Sound science consists of data, theories and laws that are widely accepted by experts.  Junk science is presented as sound science without going through the rigors of peer- review.

Limitations of Environmental Science  Inadequate data and scientific understanding can limit and make some results controversial. Scientific testing is based on disproving rather than proving a hypothesis. Scientific testing is based on disproving rather than proving a hypothesis. Based on statistical probabilities.Based on statistical probabilities.

MODELS AND BEHAVIOR OF SYSTEMS  Usefulness of models Complex systems are predicted by developing a model of its inputs, throughputs (flows), and outputs of matter, energy and information. Complex systems are predicted by developing a model of its inputs, throughputs (flows), and outputs of matter, energy and information. Models are simplifications of “real-life”. Models are simplifications of “real-life”. Models can be used to predict if-then scenarios. Models can be used to predict if-then scenarios.

Correlation  Connecting relationships, can be used with models when directing testing is not possible.  Ex: determining past climates with tree rings, gas bubbles trapped in ice, fossilized pollen grains.  Ex: mapping cholera outbreaks

Feedback Loops: How Systems Respond to Change  Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing. Positive feedback loop causes a system to change further in the same direction (e.g. erosion) Positive feedback loop causes a system to change further in the same direction (e.g. erosion) Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. seeking shade from sun to reduce stress). Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. seeking shade from sun to reduce stress).

TYPES AND STRUCTURE OF MATTER  Elements and Compounds Matter exists in chemical forms as elements and compounds. Matter exists in chemical forms as elements and compounds. Elements (represented on the periodic table) are the distinctive building blocks of matter. C, H, OElements (represented on the periodic table) are the distinctive building blocks of matter. C, H, O Compounds: two or more different elements held together in fixed proportions by chemical bonds.Compounds: two or more different elements held together in fixed proportions by chemical bonds. N2, H2, CH4, C6H12O6

Atoms Figure 2-4

Ions  An ion is an atom or group of atoms with one or more net positive or negative electrical charges.  The number of positive or negative charges on an ion is shown as a superscript after the symbol for an atom or group of atoms Hydrogen ions (H + ), Hydroxide ions (OH - ) Hydrogen ions (H + ), Hydroxide ions (OH - ) Sodium ions (Na + ), Chloride ions (Cl - ) Sodium ions (Na + ), Chloride ions (Cl - )

 The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution. Figure 2-5

Compounds and Chemical Formulas  Chemical formulas are shorthand ways to show the atoms and ions in a chemical compound. Combining Hydrogen ions (H + ) and Hydroxide ions (OH - ) makes the compound H 2 O (dihydrogen oxide, a.k.a. water). Combining Hydrogen ions (H + ) and Hydroxide ions (OH - ) makes the compound H 2 O (dihydrogen oxide, a.k.a. water). Combining Sodium ions (Na + ) and Chloride ions (Cl - ) makes the compound NaCl (sodium chloride a.k.a. salt). Combining Sodium ions (Na + ) and Chloride ions (Cl - ) makes the compound NaCl (sodium chloride a.k.a. salt).

Organic Compounds: Carbon Rules  Organic compounds contain carbon atoms combined with one another and with various other atoms such as H +, N +, or Cl -.  Contain at least two carbon atoms combined with each other and with atoms. Methane (CH 4 ) is the only exception. Methane (CH 4 ) is the only exception. All other compounds are inorganic. All other compounds are inorganic.

Organic Compounds: Carbon Rules  Hydrocarbons: compounds of carbon and hydrogen atoms (e.g. methane (CH 4 )).  Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms (e.g. DDT (C 14 H 9 Cl 5 )).  Simple carbohydrates: certain types of compounds of carbon, hydrogen, and oxygen (e.g. glucose (C 6 H 12 O 6 )).

Cells: The Fundamental Units of Life  Cells are the basic structural and functional units of all forms of life. Prokaryotic cells (bacteria) lack a distinct nucleus. Prokaryotic cells (bacteria) lack a distinct nucleus. Eukaryotic cells (plants and animals) have a distinct nucleus. Eukaryotic cells (plants and animals) have a distinct nucleus. Figure 2-6

Macromolecules, DNA, Genes and Chromosomes  Large, complex organic molecules (macromolecules) make up the basic molecular units found in living organisms. Complex carbohydrates Complex carbohydrates (saccharides)(saccharides) Proteins Proteins (amino acids)(amino acids) Nucleic acids Nucleic acids (Nucleotides)(Nucleotides) Lipids Lipids (glycerol + fatty acids)(glycerol + fatty acids) Figure 2-7

States of Matter  The atoms, ions, and molecules that make up matter are found in three physical states: solid, liquid, gaseous. solid, liquid, gaseous.  A fourth state, plasma, is a high energy mixture of positively charged ions and negatively charged electrons. The sun and stars consist mostly of plasma. The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in TV screens, gas discharge lasers, florescent light). Scientists have made artificial plasma (used in TV screens, gas discharge lasers, florescent light).

Matter Quality  Matter can be classified as having high or low quality depending on how useful it is to us as a resource. High quality matter is concentrated and easily extracted. High quality matter is concentrated and easily extracted. low quality matter is more widely dispersed and more difficult to extract. low quality matter is more widely dispersed and more difficult to extract. Figure 2-8

Fig. 2-8, p. 39 High QualityLow Quality Salt Solid Gas Coal Coal-fired power plant emissions Gasoline Automobile emissions Solution of salt in water Aluminum ore Aluminum can

CHANGES IN MATTER  Matter can change from one physical form to another or change its chemical composition. When a physical or chemical change occurs, no atoms are created or destroyed. When a physical or chemical change occurs, no atoms are created or destroyed. Law of conservation of matter.Law of conservation of matter. Physical change maintains original chemical composition. Physical change maintains original chemical composition. Chemical change involves a chemical reaction which changes the arrangement of the elements or compounds involved. Chemical change involves a chemical reaction which changes the arrangement of the elements or compounds involved. Chemical equations are used to represent the reaction.Chemical equations are used to represent the reaction.

Chemical Change  Energy is given off during the reaction as a product.

p. 39 Reactant(s)Product(s) carbon +oxygen carbon dioxide + energy C +O2O2 CO 2 energy + + black solidcolorless gas +

Types of Pollutants  Factors that determine the severity of a pollutant’s effects: chemical nature, concentration, and persistence.  Pollutants are classified based on their persistence: Degradable pollutants Degradable pollutants Biodegradable pollutants Biodegradable pollutants Slowly degradable pollutants Slowly degradable pollutants Nondegradable pollutants Nondegradable pollutants

Nuclear Changes: Radioactive Decay  Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of matter (alpha or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. Radiation is commonly used in energy production and medical applications. Radiation is commonly used in energy production and medical applications. The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope). The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope).

Nuclear Changes: Fission  Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons. Figure 2-9

Fig. 2-9, p. 41 Uranium-235 Neutron Fission Fragment Fission Fragment Energy n n n n n n

Nuclear Changes: Fusion  Nuclear fusion: two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus. Figure 2-10

ENERGY  Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion heat, electromagnetic radiationheat, electromagnetic radiation Potential energy – stored for possible use batteries, glucose moleculesbatteries, glucose molecules

Electromagnetic Spectrum  Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content. Figure 2-11

Electromagnetic Spectrum  Organisms vary in their ability to sense different parts of the spectrum. Figure 2-12

Fig. 2-13, p. 44 Low-temperature heat (100°C or less) for space heating Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Dispersed geothermal energy Low-temperature heat (100°C or lower) Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Source of Energy Relative Energy Quality (usefulness) Energy Tasks

ENERGY LAWS: TWO RULES WE CANNOT BREAK  The first law of thermodynamics: we cannot create or destroy energy. We can change energy from one form to another. We can change energy from one form to another.  The second law of thermodynamics: energy quality always decreases. When energy changes from one form to another, it is always degraded to a more dispersed form. Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.

Fig. 2-14, p. 45 Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Mechanical energy (moving, thinking, living) Chemical energy (photosynthesis)

SUSTAINABILITY AND MATTER AND ENERGY LAWS  Unsustainable High-Throughput Economies: Working in Straight Lines Converts resources to goods in a manner that promotes waste and pollution. Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15

Fig. 2-15, p. 46 High-quality energy Matter Unsustainable high-waste economy System Throughputs Inputs (from environment) Outputs (into environment) Low-quality energy (heat) Waste and pollution

Sustainable Low-Throughput Economies: Learning from Nature  Matter-Recycling-and-Reuse Economies: Working in Circles!!!! Mimics nature by recycling and reusing, thus reducing pollutants and waste. Mimics nature by recycling and reusing, thus reducing pollutants and waste. It is not sustainable for growing populations. It is not sustainable for growing populations.

Fig. 2-16, p. 47 Recycle and reuse Low-quality Energy (heat) Waste and pollution Pollution control Sustainable low-waste economy Waste and pollution Matter Feedback Energy Feedback Inputs (from environment) Energy conservation Matter Energy System Throughputs Outputs (into environment)