Chapter 2 Science, Systems, Matter, and Energy

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.

Feedback Loops: How Systems Respond to Change 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) the ice-albedo positive feedback loop whereby melting snow exposes more dark ground which in turn absorbs heat and causes more snow to melt.the ice-albedo positive feedback loop whereby melting snow exposes more dark ground which in turn absorbs heat and causes more snow to melt. Negative (corrective) feedback loop causes a system to change in the opposite direction Negative (corrective) feedback loop causes a system to change in the opposite direction predator-prey relationships in ecosystems.predator-prey relationships in ecosystems.

Examples  Positive feedback – change continues in one direction one direction

 Negative feedback – before one population grows exponentially a feedback to reverse growth occurs

Time Delays  Corrective action of the negative feedback loop takes too long

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.Elements (represented on the periodic table) are the distinctive building blocks of matter. 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.

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 monooxide, a.k.a. water). Combining Hydrogen ions (H + ) and Hydroxide ions (OH - ) makes the compound H 2 O (dihydrogen monooxide, 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 C l5 )).  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 Proteins Proteins Nucleic acids Nucleic acids Lipids Lipids 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

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

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

Laws of Thermodynamics First Law: energy cannot be created or destroyed, but it can be transformed from one form to another Sunlight  chemical energy food(photosynthesis)

Second Law: when energy is transformed, it is degraded to lower quality Gasoline combustion in car  mechanical energy + heat